A comfort-based method for optimizing the position of hard points of an automobile chassis

Abstract

The application discloses a kind of based on comfort's automobile chassis hard point position optimization method, comprising the following steps: 1) according to chassis hard point coordinate, component mass and moment of inertia, bush stiffness, damper damping and other parameters, establish suspension conceptual model, method is: a) tire model is simulated by multiple mass elements including its outer contour shape, connect each mass point along the contour surface with plot element, connect each mass point to mass center coordinate with rigid element, establish elastic element on ground surface and assign ground stiffness.The chassis conceptual model proposed in the application has the advantages of fast calculation and convenient hard point coordinate adjustment compared with detailed model; currently, the impact of hard point change is mainly based on manual adjustment of the model for comparison calculation, which is difficult to perform a large number of calculations, or difficult to summarize the optimal hard point design from a large number of calculation results; the present application can quickly and effectively obtain the optimal design of chassis hard point by using optimization algorithm to automatically find the optimal solution.

Description

Technical Field

[0001] This invention relates to the field of hard points in automotive chassis, and particularly to a method for optimizing the location of hard points in automotive chassis based on comfort. Background Technology

[0002] The location of hard points in a vehicle chassis has a significant impact on vehicle vibration, noise, and dynamic performance. Currently, the design of hard point coordinates is primarily driven by vehicle dynamics development, which is detrimental to the control of vehicle vibration and noise performance. Chassis hard point design occurs in the early stages of vehicle development, generally without a detailed full-vehicle or chassis model based on comfort considerations. Even with a detailed full-vehicle or chassis model, optimizing hard point locations requires a massive amount of computation due to the numerous variables in hard point design. Currently, the impact of hard point changes is mainly addressed through manual model adjustments and comparative calculations, which is difficult to perform extensive calculations or to summarize the optimal hard point design from a large number of calculation results. No relevant methods have been found to be in use yet. Therefore, this solution provides a new method for optimizing the location of hard points in a vehicle chassis to improve comfort. Summary of the Invention

[0003] The technical problem to be solved by this invention is to overcome the defects of the prior art and provide a comfort-based method for optimizing the hard point position of a car chassis. Compared with detailed models, this method has the advantages of fast calculation and convenient hard point coordinate adjustment. By automatically finding the optimal solution through the optimization algorithm, the optimal design of the chassis hard points can be obtained quickly and effectively.

[0004] This invention provides the following technical solution:

[0005] This invention provides a method for optimizing the location of hard points in a car chassis based on comfort, comprising the following steps:

[0006] 1) Based on parameters such as chassis hardpoint coordinates, component mass and moment of inertia, bushing stiffness, and shock absorber damping, establish a suspension conceptual model. The method is as follows:

[0007] a) The tire model is simulated by multiple mass elements containing its outer contour shape. The mass points are connected along the contour surface using plot elements, and the mass points are connected to the center of mass coordinates using rigid elements (RBE2). Elastic elements (CBUSH) are established on the ground surface and ground stiffness (obtained from experimental testing) is assigned.

[0008] b) The shock absorber is divided into two parts: the piston rod and the outer cylinder. Mass points are established at the center of mass of each part, and elastic units (such as bushes) are established at the contact points of the two parts to give contact stiffness and damping.

[0009] c) The spring is simulated by an elastic element (such as a bush), which gives the spring mass and stiffness;

[0010] d) The hub bearing is considered in two parts: fixed and rotating. An elastic unit (such as a bush) is established between the two parts to give the bearing stiffness.

[0011] e) Other components (subframe, control arm, connecting rod, brake disc, brake caliper, steering knuckle, wheel rim, etc.) all have a single mass point at their center of gravity;

[0012] f) Bushings and ball joints are simulated using elastic elements (such as bushes) and given appropriate stiffness;

[0013] g) All mass points must include the mass and moment of inertia of the corresponding component;

[0014] h) Connect the mass points of each component to each overlapping position (bulb, bearing, ball joint, bolt, etc.) using massless rigid rods (such as beam units with a diameter of 20 mm or more and an elastic modulus of more than 100 times that of steel);

[0015] 2) Constrain the six degrees of freedom of all attachment points (passive side of bushing) of the suspension conceptual model and calculate the modes. Compare the results with the typical modes of the detailed model of the same type of suspension to determine whether the modal frequencies and mode shapes are reasonable. Typical modes refer to the suspension Hop / Tramp mode, Fore-aft / Walk mode, Camber mode, and Bounce mode of the flexible connection subframe. If no relevant modes appear or the modal frequencies are too different from those of the same type of suspension (generally, the difference between the Hop / Tramp mode or Fore-aft / Walk mode is more than 10Hz, and the difference between the subframe Bounce mode is more than 20Hz), then it is necessary to check the corresponding mass, moment of inertia, and connection stiffness information according to the frequency and mode shape of the abnormal parts and adjust them to the correct parameters.

[0016] 3) Apply a frequency domain load to the wheel center and output the force curve at the chassis attachment point. Select the sum of the peak force values ​​in the road noise sensitive frequency band as the optimization target.

[0017] 4) Use optimization software (Optimus is used as an example in this invention) to build an optimization process, in which the chassis hard point coordinates (XYZ directions) in the attachment point force calculation model are used as variables, and the minimum sum of the attachment point force peak values ​​in the road noise sensitive frequency band is selected from the result file as the optimization target;

[0018] 5) You can directly select the algorithm supported by the optimization software (such as NLPQL, Self-Adaptive Evolution, etc.) to calculate the coordinate with the smallest sum of the peak values ​​of the attachment point forces involved in the calculation of all hard point coordinates. This result has the largest change in hard point coordinates and the smallest sum of the peak values ​​of the attachment point forces.

[0019] 6) The influence of each variable on the sum of the peak values ​​of the docking attachment force can be calculated first using the Monte Carlo method. Then, select a certain number of variables that have the greatest influence on the sum of the peak values ​​of the docking attachment force and eliminate variables that have a greater impact on other performance (as provided by the relevant performance department) for optimization calculation. This result is a better sum of the peak values ​​of the docking attachment force when the hard point coordinates change relatively little.

[0020] 7) Output the optimized hard point coordinates to relevant departments (such as vehicle dynamics, general layout, etc.) for feasibility verification. If there are any changes (for example, changes in certain variables cause other performance to be unacceptable, so some or all of these variables are cancelled), then the verified hard point coordinates are subjected to attachment point force verification (apply dynamic load to the wheel center and output the attachment point force curve, compare it with the base and optimization results to judge the improvement effect) or the variables are reselected for optimization calculation, and finally a consensus is reached.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Compared with detailed models, the chassis conceptual model proposed in this invention has the advantages of fast calculation and convenient hard point coordinate adjustment. Currently, the impact of hard point changes is mainly determined by manually adjusting the model for comparison calculation, which makes it difficult to perform a large number of calculations or to summarize the optimal hard point design from a large number of calculation results. This invention automatically finds the optimal solution through optimization algorithms, which can quickly and effectively obtain the optimal design of chassis hard points. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 This is a schematic diagram of the suspension concept model of the present invention;

[0025] Figure 2 This is a schematic diagram of the road noise sensitive frequency band of the present invention;

[0026] Figure 3 This is the optimization flowchart of the present invention for selecting the minimum sum of the peak values ​​of the attachment point forces in the road noise sensitive frequency band from the result file;

[0027] Figure 4 This is a flowchart illustrating the overall process of this invention. Detailed Implementation

[0028] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. All identical reference numerals in the drawings refer to the same components.

[0029] Example 1

[0030] like Figure 1-4 This invention provides a method for optimizing the location of hard points in a car chassis based on comfort, comprising the following steps:

[0031] 1) Based on parameters such as chassis hardpoint coordinates, component mass and moment of inertia, bushing stiffness, and shock absorber damping, establish a suspension conceptual model. The method is as follows:

[0032] a) The tire model is simulated by multiple mass elements containing its outer contour shape. The mass points are connected along the contour surface using plot elements, and the mass points are connected to the center of mass coordinates using rigid elements (RBE2). Elastic elements (CBUSH) are established on the ground surface and ground stiffness (obtained from experimental testing) is assigned.

[0033] b) The shock absorber is divided into two parts: the piston rod and the outer cylinder. Mass points are established at the center of mass of each part, and elastic units (such as bushes) are established at the contact points of the two parts to give contact stiffness and damping.

[0034] c) The spring is simulated by an elastic element (such as a bush), which gives the spring mass and stiffness;

[0035] d) The hub bearing is considered in two parts: fixed and rotating. An elastic unit (such as a bush) is established between the two parts to give the bearing stiffness.

[0036] e) Other components (subframe, control arm, connecting rod, brake disc, brake caliper, steering knuckle, wheel rim, etc.) all have a single mass point at their center of gravity;

[0037] f) Bushings and ball joints are simulated using elastic elements (such as bushes) and given appropriate stiffness;

[0038] g) All mass points must include the mass and moment of inertia of the corresponding component;

[0039] h) Connect the mass points of each component to each overlapping position (bulb, bearing, ball joint, bolt, etc.) using massless rigid rods (such as beam units with a diameter of 20 mm or more and an elastic modulus of more than 100 times that of steel);

[0040] i) Conceptual model diagram as shown Figure 1 As shown (front view of multi-link rear suspension, dots represent mass points, straight lines represent rigid links, and spirals represent elastic elements);

[0041] 2) Constrain the six degrees of freedom of all attachment points (passive side of bushing) of the suspension conceptual model and calculate the modes. Compare the results with the typical modes of the detailed model of the same type of suspension to determine whether the modal frequencies and mode shapes are reasonable. Typical modes refer to the suspension Hop / Tramp mode, Fore-aft / Walk mode, Camber mode, and Bounce mode of the flexible connection subframe. If no relevant modes appear or the modal frequencies are too different from those of the same type of suspension (generally, the difference between the Hop / Tramp mode or Fore-aft / Walk mode is more than 10Hz, and the difference between the subframe Bounce mode is more than 20Hz), then it is necessary to check the corresponding mass, moment of inertia, connection stiffness and other information according to the frequency and mode shape of the abnormal parts, and adjust them to the correct parameters.

[0042] 3) Apply a frequency domain load to the chassis attachment point force curve at the wheel center, and select the sum of the peak force values ​​in the road noise-sensitive frequency band as the optimization target, for example... Figure 2 The sum of the maximum values ​​of the curves in the ranges of 20-60Hz, 61-100Hz, 101-150Hz, and 151-200Hz can be selected. Non-road noise sensitive frequency bands below 20Hz are not selected.

[0043] 4) An optimization process is built using optimization software (Optimus is used as an example in this invention). The chassis hardpoint coordinates (XYZ directions) in the attachment point force calculation model are used as variables. The optimization objective is to minimize the sum of the peak attachment point forces in the road noise-sensitive frequency band from the results file. An example of the optimization process is shown below. Figure 3 As shown;

[0044] 5) You can directly select the algorithm supported by the optimization software (such as NLPQL, Self-Adaptive Evolution, etc.) to calculate the coordinate with the smallest sum of the peak values ​​of the attachment point forces involved in the calculation of all hard point coordinates. This result has the largest change in hard point coordinates and the smallest sum of the peak values ​​of the attachment point forces.

[0045] 6) The influence of each variable on the sum of the peak values ​​of the docking attachment force can be calculated first using the Monte Carlo method. Then, select a certain number of variables that have the greatest influence on the sum of the peak values ​​of the docking attachment force and eliminate variables that have a greater impact on other performance (as provided by the relevant performance department) for optimization calculation. This result is a better sum of the peak values ​​of the docking attachment force when the hard point coordinates change relatively little.

[0046] 7) Output the optimized hard point coordinates to relevant departments (such as vehicle dynamics, general layout, etc.) for feasibility verification. If there are any changes (for example, changes in certain variables cause other performance to be unacceptable, so some or all of these variables are cancelled), then the verified hard point coordinates are subjected to attachment point force verification (apply dynamic load to the wheel center and output the attachment point force curve, compare it with the base and optimization results to judge the improvement effect) or the variables are reselected for optimization calculation, and finally a consensus is reached.

[0047] Furthermore,

[0048] This invention proposes a method for establishing a chassis conceptual model;

[0049] This invention proposes an optimization method that applies wheel center loads to a chassis conceptual model to output chassis attachment point forces, with chassis hard point coordinates as variables and the goal of minimizing the sum of the peak values ​​of attachment point forces.

[0050] Compared with detailed models, the chassis conceptual model proposed in this invention has the advantages of fast calculation and convenient hard point coordinate adjustment. Currently, the impact of hard point changes is mainly determined by manually adjusting the model for comparison calculation, which makes it difficult to perform a large number of calculations or to summarize the optimal hard point design from a large number of calculation results. This invention automatically finds the optimal solution through optimization algorithms, which can quickly and effectively obtain the optimal design of chassis hard points.

[0051] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing the location of hard points in a car chassis based on comfort considerations, characterized in that, Includes the following steps: 1) Based on the chassis hardpoint coordinates, component mass and moment of inertia, bushing stiffness, and damper damping parameters, establish a suspension conceptual model using the following method: a) The tire model is simulated by multiple mass elements containing its outer contour shape. Plot elements are used to connect each mass point along the contour surface, and rigid elements are used to connect each mass point to the center of mass coordinates. Elastic elements are established on the ground surface and ground stiffness is assigned. b) The shock absorber is divided into two parts: a piston rod and an outer cylinder. Mass points are established at the center of mass of each part, and elastic units are established at the contact point of the two parts to give contact stiffness and damping. c) The spring is simulated by an elastic element, which gives the spring mass and stiffness; d) The hub bearing is considered in two parts: fixed and rotating. An elastic unit is established between the two parts to give the bearing stiffness. e) The subframe, control arms, connecting rods, brake discs, brake calipers, steering knuckles, and wheel rims each establish a single mass point at their center of gravity; f) The bushings and ball joints are simulated using elastic elements and given corresponding stiffness; g) All mass points must include the mass and moment of inertia of the corresponding component; h) Connect the mass points of each component to each overlapping position using a massless rigid rod; 2) Constrain the six degrees of freedom of all attachment points of the suspension conceptual model and calculate the modes. Compare the results of typical modes with the detailed models of the same type of suspension to determine whether the modal frequencies and mode shapes are reasonable. Typical modes refer to the suspension Hop / Tramp mode, Fore-aft / Walk mode, Camber mode, and Bounce mode of the flexible connection subframe. If no relevant modes appear or the modal frequencies are too different from those of the same type of suspension, it is necessary to check the corresponding mass, moment of inertia, and connection stiffness information according to the frequency and mode shape of the abnormal parts and adjust them to the correct parameters. 3) Apply a frequency domain load to the wheel center and output the force curve at the chassis attachment point. Select the sum of the peak force values ​​in the road noise sensitive frequency band as the optimization target. 4) Use optimization software to build an optimization process, where the chassis hard point coordinates in the attachment point force calculation model are used as variables, and the minimum sum of the attachment point force peak values ​​in the road noise sensitive frequency band is selected as the optimization target from the result file. 5) You can directly select the algorithm supported by the optimization software to calculate the coordinate with the smallest sum of the peak values ​​of the attachment point forces among all hard point coordinates. This result has the largest change in hard point coordinates and the smallest sum of the peak values ​​of the attachment point forces. 6) The influence of each variable on the sum of the peak values ​​of the docking attachment force can be calculated first using the Monte Carlo method. Then, select a certain number of variables that have the greatest influence on the sum of the peak values ​​of the docking attachment force and eliminate variables that have a significant impact on other performance for optimization calculation. This result is a better sum of the peak values ​​of the docking attachment force when the hard point coordinates change relatively little. 7) Perform a feasibility check on the optimized hard point coordinates. If there are any changes, verify the attachment force on the checked hard point coordinates or reselect variables for optimization calculation.

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