A method and apparatus for predicting the dynamic dimensions of a leaf spring

Abstract

This invention relates to the field of automotive engineering technology and provides a method for predicting the dynamic dimensions of leaf springs, comprising the following steps: S1, inputting the determined arc length S and arc height H of the leaf spring into a leaf spring parameter calculation model, and outputting leaf spring parameters, including the radius R, central angle α, and chord length L of the leaf spring; S2, applying the corrected leaf spring parameters to the overall vehicle hardpoint design and general layout drawing through two iterative approximations. When setting the arc length and arc height of the leaf spring, the central angle, radius, and chord length of the main leaf spring plate with engineering precision can be analyzed, satisfying the various dimensions required for drawing the characteristic graphics of the main leaf spring plate with engineering precision, and meeting the boundary requirements of the hardpoints of the leaf spring in the overall vehicle design for the general layout design.

Description

Technical Field

[0001] This invention relates to the field of automotive engineering technology, and provides a method and apparatus for predicting the dynamic dimensions of leaf springs. Background Technology

[0002] In automobiles, leaf springs are typically fixed at one end to a pin and can rotate, while the other end is fixed to a rocker arm with a pin and can rotate and extend. When a leaf spring is compressed or rebounded under stress, the shape of the neutral layer of the main leaf along its entire length can be approximated as an arc whose radius changes with the curvature of the arc under the load. The arc is of constant length under the design load.

[0003] During the process of designing the overall vehicle hardpoints and drawing the general layout diagrams for leaf springs, the general layout engineer needs to define the typical load dimensions of the leaf springs, especially the main leaf springs. The length and arc height of the main leaf springs need to be adaptively adjusted according to the requirements and changes of the surrounding environment, and the related dimensions such as chord length and radius change accordingly. The current dynamic dimensions of leaf springs are gradually approximated by adjusting the graphic dimensions using drawing software. The drawbacks of this method are low efficiency and poor consistency. Summary of the Invention

[0004] This invention provides a method for predicting the dynamic dimensions of leaf springs, aiming to improve the above-mentioned problems.

[0005] This invention is implemented as follows: a method for predicting the dynamic dimensions of a leaf spring, the method specifically including the following steps:

[0006] S1. Input the determined arc length S and arc height H of the leaf spring into the leaf spring parameter calculation model, and output the leaf spring parameters, including the radius R, central angle α and chord length L of the leaf spring.

[0007] S2. The calculated leaf spring parameters are approximated through iterative means, and the corrected leaf spring parameters are used for the design of the vehicle's hard points and the drawing of the overall layout.

[0008] Furthermore, the method for determining the arc length S of the leaf spring is as follows:

[0009] The arc length S of the leaf spring is determined based on the wheelbase between the front and rear axles of the vehicle.

[0010] Furthermore, the specific method for determining the arc height H of the leaf spring is as follows:

[0011] The suspension bias frequency n is determined based on the overall vehicle comfort index, which in turn determines the arc height deformation f of the leaf spring, and then the arc height H of the leaf spring.

[0012] Furthermore, the specific calculation model for the parameters of the leaf spring is as follows:

[0013] L≈S

[0014]

[0015]

[0016] Furthermore, the square of the deviation rate of the central angle radian value is used to iteratively approximate the true value, and the iteration coefficient that meets the accuracy requirements is calculated. Based on the iteration coefficient, the radius R, central angle α, and chord length L of the leaf spring are corrected.

[0017] Furthermore, the iteration coefficients are:

[0018]

[0019] In the formula, α * α represents the central angle in radians obtained in the previous iteration. * The initial value is the central angle α obtained in step S1. The iteration is completed twice and then no further iterations are performed, using β. * This represents the iteration coefficient obtained in the last iteration;

[0020] Corrected leaf spring radius:

[0021] Corrected leaf spring chord length:

[0022] Corrected central angle of the leaf spring:

[0023] This invention is implemented as follows: a dynamic dimension prediction device for leaf springs, the device comprising:

[0024] The system includes an input unit, a parameter calculation unit, and a parameter correction unit, wherein the input unit is connected to the parameter calculation unit, and the parameter calculation unit is connected to the parameter correction unit.

[0025] The predetermined arc length S and arc height H of the leaf spring are input through the input unit and sent to the parameter calculation unit.

[0026] The parameter calculation unit calculates the radius R, central angle α, and chord length L of the leaf spring.

[0027] The parameter correction unit corrects the calculated values ​​of the radius R, central angle α, and chord length L of the leaf spring.

[0028] Furthermore, the parameter calculation unit calculates the radius R, central angle α, and chord length L of the leaf spring based on the following model, which is as follows:

[0029] L≈S

[0030]

[0031]

[0032] Furthermore, the parameter correction unit iteratively approximates the true value based on the square of the deviation rate of the central angle in radians, obtaining the iteration coefficients as follows:

[0033]

[0034] In the formula, α * α represents the central angle in radians obtained in the previous iteration. * The initial value is the central angle α obtained in step S1. The iteration is completed twice and then no further iterations are performed, using β. * This represents the iteration coefficient obtained in the last iteration;

[0035] Based on iteration coefficient β * To correct the radius R, central angle α, and chord length L of the leaf spring, the corrected radius R′, central angle α′, and chord length L′ are given. The corrected radius of the leaf spring is then calculated. Corrected leaf spring chord length: Corrected central angle of the leaf spring:

[0036] When setting the arc length and arc height of the leaf spring, this invention can analyze the central angle, radius, and chord length of the main leaf spring plate with engineering precision, satisfying all the dimensions required for drawing the feature graphics of the main leaf spring plate with engineering precision. It also meets the boundary requirements of the hard points of the leaf spring in the overall vehicle design for the overall layout design. In addition, when the boundary conditions of the leaf spring layout change, the boundary change of the leaf spring can be completed quickly, improving the efficiency and quality of the overall layout design. Attached Figure Description

[0037] Figure 1 A flowchart of the dynamic dimension estimation method for leaf springs provided in this embodiment of the invention;

[0038] Figure 2 This is a schematic diagram of the dimensional geometry analysis of a leaf spring provided in an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the dynamic dimension prediction device for leaf springs provided in an embodiment of the present invention. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0041] Figure 1 The flowchart of the dynamic dimension estimation method for leaf springs provided in this embodiment of the invention includes the following steps:

[0042] S1. The arc length S of the leaf spring is set based on the wheelbase between the front and rear axles of the vehicle.

[0043] In this embodiment of the invention, the front and rear suspensions of the automobile are composed of leaf springs and shock absorbers. Typically, the arc length of the front leaf spring of a truck is (0.26 to 0.35) of the wheelbase, and the arc length of the rear leaf spring is (0.35 to 0.45) of the wheelbase. The arc length S of the leaf spring is further modified by referring to similar competing products in the market and the overall vehicle layout space.

[0044] S2. Determine the suspension bias frequency n based on the overall vehicle comfort index, then determine the arc height deformation f of the leaf spring, and finally determine the arc height H of the leaf spring.

[0045] The relationship between the front suspension offset frequency n (in Hz) and the leaf spring deformation f (in mm) is as follows: Typically, the front suspension deflection frequency of a truck is taken in the range of 1.3 to 2.1, and the rear suspension deflection frequency is taken in the range of 1.7 to 2.2. The deformation amount f of the leaf spring is determined based on the suspension deflection frequency n.

[0046] The initial arc height H0 is determined based on the overall vehicle height and the constraint boundary between the leaf spring's upward jump and the upper buffer block when the leaf spring's runout is satisfied. The initial arc height should be minimized as much as possible when design conditions allow. The sum of the initial arc height and the arc height deformation is the arc height, H = H0 + f, where f is taken as a positive value if it increases the arc height and a negative value otherwise.

[0047] S3. Input the arc length S and arc height H of the leaf spring into the leaf spring parameter calculation model, and output the leaf spring parameters, including the radius R, central angle α and chord length L of the leaf spring.

[0048] Combination Figure 2 To explain, in Figure 2 In the diagram, the chord length of the leaf spring is L, the arc length of the leaf spring is S, the central angle of the leaf spring is α, the arc radius of the leaf spring is R, and the arc height of the leaf spring is H.

[0049] Since the central angle α of the main leaf spring is mostly an acute angle less than 50°, the sine can be approximately equal to the radian value of the angle within 27°, and the value of the sine will be smaller than the actual radian value. Therefore, it can be considered... Based on this, we can conclude that:

[0050] L≈S

[0051]

[0052]

[0053] S4. The overall layout design of the main leaf spring is set with the arc length S value being more than ten times the arc height H. The calculated leaf spring parameters are then applied to the whole vehicle hard point design and overall layout drawing through iterative approximation.

[0054] In this embodiment of the invention, the square of the deviation rate of the central angle in radians is used to iteratively approximate the true value. Verification on commonly used leaf springs has shown that after two iterations, the accuracy is less than the ten-thousandth percentile or lower, meeting the engineering design accuracy requirements. The calculated iteration coefficient β is:

[0055]

[0056] In the formula, α * α represents the central angle in radians obtained in the previous iteration. * The initial value is the central angle α obtained in step S1. The iteration is completed twice and then no further iterations are performed, using β. * This represents the iteration coefficient obtained in the last iteration.

[0057] Based on iteration coefficient β * To correct the radius R, central angle α, and chord length L of the leaf spring, the corrected radius R′, central angle α′, and chord length L′ are given. The corrected radius of the leaf spring is then calculated.

[0058] Based on geometric analysis, we know that: Therefore, the corrected chord length of the leaf spring is:

[0059] Corrected central angle of the leaf spring:

[0060] Figure 3 This is a schematic diagram of the dynamic dimension prediction device for leaf springs provided in an embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown.

[0061] The device includes:

[0062] The system includes an input unit, a parameter calculation unit, and a parameter correction unit, wherein the input unit is connected to the parameter calculation unit, and the parameter calculation unit is connected to the parameter correction unit.

[0063] The predetermined arc length S and arc height H of the leaf spring are input through the input unit and sent to the parameter calculation unit.

[0064] The parameter calculation unit calculates the radius R, central angle α, and chord length L of the leaf spring.

[0065] The parameter calculation unit calculates the radius R, central angle α, and chord length L of the leaf spring based on the following model, which is as follows:

[0066] L≈S

[0067]

[0068]

[0069] The parameter correction unit corrects the calculated values ​​of the radius R, central angle α, and chord length L of the leaf spring.

[0070] In this embodiment of the invention, the parameter correction unit iteratively approximates the true value based on the square of the deviation rate of the central angle in radians, obtaining the iteration coefficient β as follows:

[0071]

[0072] In the formula, α * α represents the central angle in radians obtained in the previous iteration. * The initial value is the central angle α obtained in step S1. The iteration is completed twice and then no further iterations are performed, using β. * This represents the iteration coefficient obtained in the last iteration.

[0073] Based on iteration coefficient β * To correct the radius R, central angle α, and chord length L of the leaf spring, the corrected radius R′, central angle α′, and chord length L′ are given. The corrected radius of the leaf spring is then calculated. Corrected leaf spring chord length: Corrected central angle of the leaf spring:

[0074] When setting the arc length and arc height of the leaf spring, this invention can analyze the central angle, radius, and chord length of the main leaf spring plate with engineering precision, satisfying all the dimensions required for drawing the feature graphics of the main leaf spring plate with engineering precision. It also meets the boundary requirements of the hard points of the leaf spring in the overall vehicle design for the overall layout design. In addition, when the boundary conditions of the leaf spring layout change, the boundary change of the leaf spring can be completed quickly, improving the efficiency and quality of the overall layout design.

[0075] The present invention has been described by way of example. 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 of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for predicting the dynamic dimensions of a leaf spring, characterized in that, The method specifically includes the following steps: S1. Determine the arc length of the leaf spring. and arc height Input a calculation model for leaf spring parameters, and output leaf spring parameters, including the radius of the leaf spring. Central angle and chord length ; S2. The leaf spring parameters output by the leaf spring parameter model are corrected by iterative approximation, and the corrected leaf spring parameters are used for the design of hard points of the whole vehicle and the drawing of the general layout drawing. The parameters of the leaf spring output by the parameter model are corrected through iterative approximation. This includes: using the square of the deviation rate of the central angle radians to iteratively approximate the true value, calculating the iterative coefficients that meet the accuracy requirements, and then correcting the radius of the leaf spring based on these iterative coefficients. Central angle and chord length ; The iteration coefficients are: ； In the formula, This represents the central angle value in radians obtained in the previous iteration. The initial value is the central angle. ; Corrected leaf spring radius: ; Corrected leaf spring chord length: ; Corrected central angle of the leaf spring: ; In the formula, This represents the iteration coefficient obtained in the last iteration.

2. The method for predicting the dynamic dimensions of a leaf spring as described in claim 1, characterized in that, leaf spring arc length The specific method for determining it is as follows: The arc length S of the leaf spring is determined based on the wheelbase between the front and rear axles of the vehicle.

3. The method for predicting the dynamic dimensions of a leaf spring as described in claim 1, characterized in that, leaf spring arc height The specific method for determining it is as follows: Based on the overall vehicle comfort index, the suspension bias frequency n is determined, and then the arc height deformation f of the leaf spring is determined, thus determining the arc height of the leaf spring. .

4. The method for predicting the dynamic dimensions of a leaf spring as described in claim 1, characterized in that, The specific calculation model for the parameters of a leaf spring is as follows: ； ； 。 5. A dynamic dimension prediction device for leaf springs, characterized in that, The device includes: The system includes an input unit, a parameter calculation unit, and a parameter correction unit, wherein the input unit is connected to the parameter calculation unit, and the parameter calculation unit is connected to the parameter correction unit. The predetermined arc length of the leaf spring is input through the input unit. and arc height And send it to the parameter calculation unit; The parameter calculation unit calculates the radius of the leaf spring. Central angle and chord length ; Parameter correction unit, for the radius of the leaf spring Central angle and chord length The calculated values ​​are corrected; The parameter correction unit iteratively approximates the true value based on the square of the deviation rate of the central angle in radians, obtaining the iteration coefficients as follows: ； In the formula, This represents the central angle value in radians obtained in the previous iteration. The initial value is the central angle. ; Based on the iteration coefficients obtained from the last iteration To correct the radius of the leaf spring Central angle and chord length Corrected radius Central angle and chord length The radius of the leaf spring after the spring is turned out: The corrected chord length of the leaf spring: The corrected central angle of the leaf spring: ,in This represents the iteration coefficient obtained in the last iteration.

6. The dynamic dimension prediction device for leaf springs as described in claim 5, characterized in that, The parameter calculation unit calculates the radius of the leaf spring based on the following model. Central angle and chord length The specific calculation model is as follows: ； ； 。

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