A vehicle suspension dynamic damping coefficient testing method and system

Abstract

This invention provides a method and system for testing the dynamic damping coefficient of vehicle suspension, relating to the field of suspension testing. Addressing the problems of time-consuming, labor-intensive, and inefficient testing methods using existing bench tests for dynamic damping coefficient determination, and the significant deviations in damping parameter measurements due to the difficulty in accurately reproducing actual suspension operating conditions, this invention determines the dynamic damping coefficient of the suspension based on the sprung mass resonance condition. Accelerometers are installed at both the non-sprung mass and sprung mass locations. The amplitude ratio at sprung mass resonance is measured using vehicle driving conditions. The dynamic damping coefficient is then derived by combining the sprung mass resonance frequency, suspension spring dynamic stiffness, and sprung mass parameters. This method eliminates the need for bench testing and disassembly of spring damping components, offering high efficiency, speed, and convenience. The measurement process is based on the vehicle's overall driving conditions, with suspension spring displacement deformation and applied loads fed back from actual operating conditions, resulting in more accurate results.

Description

Technical Field

[0001] This invention relates to the field of suspension testing, and more specifically to a method and system for testing the dynamic damping coefficient of vehicle suspension. Background Technology

[0002] The automotive suspension, composed of elastic elements, shock absorbers, and guiding mechanisms, plays a crucial role in the ride smoothness and passenger comfort during vehicle operation. Commonly used elastic elements include leaf springs, coil springs, air springs, and hydropneumatic springs. During vehicle operation, shock absorbers and other components provide damping force, dissipating the energy transmitted from the road surface to the sprung mass and reducing vibration. Furthermore, due to friction, suspension components exhibit hysteresis in the vertical direction, also generating a certain vertical damping force. In suspension matching, the sum of shock absorber damping and suspension friction damping is a critical parameter affecting vehicle ride smoothness, especially during sprung mass resonance. Improper damping matching can lead to amplified vibration amplitude and deteriorated comfort; therefore, effective measurement and calibration of the suspension dynamic damping coefficient are essential.

[0003] Currently, suspension damping is mostly measured through bench tests. The work done by the damping force during a single cycle is obtained from the load-unload curve of the bench test, and the equivalent damping coefficient of the suspension is calculated based on this. However, suspension springs have nonlinear characteristics, and due to factors such as friction, the damping characteristics exhibited by the same elastic element under different axle loads and road excitations may vary when the sprung mass resonates. Bench tests are difficult to reproduce various actual operating conditions. Actual testing not only requires disassembling components but also necessitates additional displacement sensors to measure suspension amplitude. The testing process is complex, time-consuming, labor-intensive, and inefficient, resulting in large deviations and low accuracy in the obtained damping parameters, making it difficult to meet the requirements for measuring dynamic suspension damping. Summary of the Invention

[0004] To address the aforementioned technical shortcomings, this invention provides a method for testing the dynamic damping coefficient of a vehicle suspension. The method measures the amplitude ratio of sprung and unsprung measurement points when the sprung mass resonates under vehicle driving conditions. Based on the amplitude ratio, sprung mass resonance frequency, suspension spring dynamic stiffness, and sprung mass parameters, the suspension damping coefficient is derived, enabling accurate and efficient acquisition of the suspension damping coefficient.

[0005] The first objective of this invention is to provide a method for testing the dynamic damping coefficient of a vehicle suspension, employing the following scheme:

[0006] The acceleration signals of the unsprung mass and the sprung mass are obtained, processed and the resonant frequency of the sprung mass is identified. The amplitude-frequency values ​​of the unsprung mass and the sprung mass are obtained, and the amplitude ratio of the unsprung mass and the sprung mass is calculated.

[0007] A two-degree-of-freedom dynamic model of the suspension is established and the dynamic differential equation is obtained. Based on the differential equation, the vibration amplitude related quantities and equivalent relationships transmitted to the sprung mass after the vehicle suspension damping are constructed. Based on the equivalent relationship, the dynamic damping coefficient of the vehicle suspension when the sprung mass resonates is calculated by combining the amplitude ratio, the sprung mass resonance frequency, the suspension spring dynamic stiffness and the sprung mass.

[0008] Furthermore, when the vehicle is traveling on a straight road, the acceleration signals of the unsprung mass and the sprung mass are obtained.

[0009] Furthermore, when the vehicle is in acceleration or coasting conditions, the acceleration signals of the unsprung mass and the sprung mass are acquired.

[0010] Furthermore, the post-processing identification of the resonant frequency of the sprung mass includes:

[0011] The acceleration signal is subjected to spectral transformation, and the resonant phenomenon of the sprung mass is identified based on the spectrum, and the resonant frequency of the sprung mass is identified.

[0012] Furthermore, after identifying the resonant frequency of the sprung mass, the rotational speed characteristic parameters at the sprung mass resonance are recorded;

[0013] Multiple rounds of uniform speed tests were conducted based on rotational speed characteristic parameters. The amplitude ratio of the unsprung mass and sprung mass parts in each round of test was recorded, and the average value was calculated and then substituted into the formula for calculating the dynamic damping coefficient.

[0014] Furthermore, the speed characteristic parameter is one of the vehicle speed, engine speed in a certain gear, and drive shaft speed in a certain gear.

[0015] Furthermore, the acceleration signal is the acceleration data of the unsprung mass portion and the sprung mass portion along the vertical direction of the ground.

[0016] Furthermore, the dynamic stiffness of the suspension spring is obtained through prior testing.

[0017] A second objective of the present invention is to provide a vehicle suspension dynamic damping coefficient testing system as described in the first objective, comprising:

[0018] The parameter acquisition module is configured to: acquire the acceleration signals of the unsprung mass and the sprung mass, process them to identify the resonant frequency of the sprung mass, acquire the amplitude-frequency values ​​of the unsprung mass and the sprung mass, and calculate the amplitude ratio of the unsprung mass and the sprung mass.

[0019] The dynamic damping coefficient calculation module is configured to: establish a two-degree-of-freedom dynamic model of the suspension and obtain the dynamic differential equation; construct the vibration amplitude related quantity and equivalent relationship transmitted to the sprung mass after the vehicle suspension damping effect based on the differential equation; and calculate the dynamic damping coefficient of the vehicle suspension when the sprung mass resonates based on the equivalent relationship, combined with the amplitude ratio, sprung mass resonance frequency, suspension spring dynamic stiffness and sprung mass.

[0020] Furthermore, after identifying the resonant frequency of the sprung mass, the rotational speed characteristic parameters at the sprung mass resonance are recorded;

[0021] Multiple rounds of uniform speed tests were conducted based on rotational speed characteristic parameters. The amplitude ratio of the unsprung mass and sprung mass parts in each round of test was recorded, and the average value was calculated and then substituted into the formula for calculating the dynamic damping coefficient.

[0022] Compared with the prior art, the advantages and positive effects of this invention are:

[0023] To address the problem that current bench tests struggle to reproduce actual suspension operating conditions, thus hindering the accurate measurement of suspension dynamic damping, this invention determines the suspension dynamic damping coefficient based on sprung mass resonance conditions. Accelerometers are installed at both the sprung and unsprung mass locations. By measuring the amplitude ratio at sprung mass resonance under vehicle driving conditions, and combining this with the sprung mass resonance frequency, suspension spring dynamic stiffness, and sprung mass parameters, the dynamic damping coefficient is derived. This invention eliminates the need for bench testing and disassembly of spring damping components, offering high efficiency, speed, and convenience. The measurement process is based on the vehicle's overall driving conditions, with suspension spring displacement deformation and applied loads fed back from actual operating conditions, resulting in more accurate results. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a flowchart illustrating the method for testing the dynamic damping coefficient of vehicle suspension in one or more embodiments of the present invention. Detailed Implementation

[0026] Example 1

[0027] In a typical embodiment of the present invention, such as Figure 1 As shown, a method for testing the dynamic damping coefficient of vehicle suspension is presented.

[0028] There are certain limitations in determining the sprung mass resonance damping coefficient. Measuring the vehicle suspension damping coefficient by simulating sprung mass resonance conditions on a test bench is cumbersome and can lead to significant deviations in the results. Therefore, this embodiment provides a method for testing the dynamic damping coefficient of a vehicle suspension, including:

[0029] The acceleration signals of the unsprung mass and the sprung mass are obtained, processed and the resonant frequency of the sprung mass is identified. The amplitude-frequency values ​​of the unsprung mass and the sprung mass are obtained, and the amplitude ratio of the unsprung mass and the sprung mass is calculated.

[0030] A two-degree-of-freedom dynamic model of the suspension is established and the dynamic differential equation is obtained. Based on the differential equation, the vibration amplitude related quantities and equivalent relationships transmitted to the sprung mass after the vehicle suspension damping are constructed. Based on the equivalent relationship, the dynamic damping coefficient of the vehicle suspension when the sprung mass resonates is calculated by combining the amplitude ratio, the sprung mass resonance frequency, the suspension spring dynamic stiffness and the sprung mass.

[0031] The process of identifying the resonant frequency of the sprung mass after processing includes: performing a spectral transformation on the acceleration signal, identifying the sprung mass resonance phenomenon based on the spectrum, and identifying the resonant frequency of the sprung mass.

[0032] After identifying the resonant frequency of the sprung mass, the rotational speed characteristic parameters at the sprung mass resonance are recorded.

[0033] Multiple rounds of uniform speed tests were conducted based on rotational speed characteristic parameters. The amplitude ratio of the unsprung mass and sprung mass parts in each round of test was recorded, and the average value was calculated and then substituted into the formula for calculating the dynamic damping coefficient.

[0034] The dynamic stiffness of the suspension springs is obtained through preliminary testing. For example, a bench test simulation method can be used, where the suspension is removed from the vehicle and placed on specialized testing equipment to simulate the loads experienced by the vehicle during operation, vibrations caused by road bumps, etc. Periodic load excitations are applied to the suspension, and the magnitude of the force and deformation of the vehicle suspension under different excitations are recorded. Based on the core logic of force / deformation, combined with the vibration frequency, the dynamic stiffness under different operating conditions is calculated.

[0035] In other alternative implementations, the inverse method based on driving conditions can be used. Given parameters such as resonant frequency, unsprung mass (weight of components such as axles and tires), sprung mass (weight of the vehicle body and engine), and tire stiffness, the dynamic stiffness of the vehicle suspension springs can be calculated by substituting them into existing formulas.

[0036] Specifically, the test method for the dynamic damping coefficient of vehicle suspension includes the following steps:

[0037] Step 1: After placing acceleration sensors at both the unsprung mass and sprung mass locations, drive the vehicle onto the test road.

[0038] Step two involves conducting driving condition tests. The acceleration signals measured by the accelerometer are subjected to frequency domain transformation. Based on the spectrum, the sprung mass resonance phenomenon is identified, and the amplitude ratio of the sprung mass and the unsprung mass is calculated. The calculation formula is:

[0039] (1);

[0040] in, The amplitude-frequency value of the unsprung mass. The amplitude-frequency value of the sprung mass.

[0041] Step 3: Establish a two-degree-of-freedom dynamic model of the vehicle suspension and derive its dynamic differential equations. Solve the equations based on the amplitude equivalence relationship under resonance conditions, and determine the solution based on the amplitude ratio. Spring-loaded mass resonant frequency Suspension spring dynamic stiffness Spring mass Determining the dynamic damping coefficient of vehicle suspension during sprung mass resonance The calculation formula is as follows:

[0042] (2);

[0043] in, ω is the angular frequency.

[0044] In step three, the amplitude ratio is calculated by taking the average value, and the average amplitude ratio is recorded as follows. When the sprung mass resonates, the dynamic damping coefficient of the suspension... The calculation formula is:

[0045] (3);

[0046] in, Angular frequency.

[0047] In equation (3), the average amplitude ratio The methods for obtaining it include:

[0048] The first step is to identify the sprung mass resonance phenomenon based on the spectrum when the vehicle is under driving conditions, and record the rotational speed characteristic parameters when the sprung mass resonates.

[0049] The second step involves conducting N rounds of constant-speed testing based on the rotational speed characteristic parameters. Record the ratio of the resonant amplitude of the spring-loaded mass in each round of testing. ,in ;

[0050] The third step is to average the N amplitude ratios to obtain the average amplitude ratio:

[0051] (4);

[0052] In the first step, the speed characteristic parameter is one of the vehicle speed, engine speed in a certain gear, and drive shaft speed in a certain gear. In the second step, the test road for the constant speed test is the same section of road in the same direction, and the test road is a straight section of a high-grade highway.

[0053] The acceleration signal consists of acceleration data of both the unsprung mass and sprung mass components along the vertical direction from the ground. Therefore, in step one, the measurement direction of the acceleration sensor is perpendicular to the ground. In step two, the driving condition is one of acceleration or coasting.

[0054] In step two, after the frequency domain transformation of the accelerometer readings from the unsprung mass and the sprung mass locations, the amplitude and frequency values ​​simultaneously exhibit local maximum values ​​at the same frequency. The amplitude of the sprung mass is greater than that of the unsprung mass, while the phase frequency values ​​are equal at this frequency. This can be identified as a sprung mass resonance phenomenon. The ratio of the amplitudes of the unsprung mass to the sprung mass at this frequency is recorded as the amplitude ratio. .

[0055] In this embodiment, the method for determining the dynamic damping coefficient of vehicle suspension involves placing acceleration sensors at both the non-sprung mass and sprung mass locations, measuring the sprung mass resonance amplitude ratio under vehicle driving conditions, and determining the vehicle suspension dynamic damping coefficient based on the sprung mass resonance amplitude ratio and according to the sprung mass resonance frequency, suspension spring dynamic stiffness, and sprung mass parameters. This provides guidance and verification for the design and matching of vehicle suspension.

[0056] In one implementation of this embodiment: taking a single-side suspension of a certain leaf spring suspension system as an example, the suspension damper is removed and the suspension friction damping coefficient is measured.

[0057] Among them, the resonant frequency of the spring-loaded mass =2.85Hz, dynamic stiffness of single-side suspension spring =800000 N / m, single-sided spring load =820kg, the measurement steps are as follows:

[0058] Step 1: Place unidirectional acceleration sensors on both the unsprung mass and sprung mass sections of the front suspension, ensuring the measurement direction of these sensors is perpendicular to the ground. This allows for the use of vertical data changes to determine the presence of resonance. Select a straight section of a high-grade highway in a suburban area as the test road; ideally, choose a section without curves or slopes. To improve the accuracy of the measurement data and reduce the adverse effects of external testing conditions, the selected test road conditions should be controlled to have a road surface slope of less than 1%, uniform unevenness without abrupt changes, and a dry road surface during the test.

[0059] Step Two: Testing was conducted under acceleration conditions. At a vehicle speed of 30 km / h, local peak values ​​appeared in the amplitude-frequency values ​​perpendicular to the ground at both the sprung mass and unsprung mass measuring points. Simultaneously, the sprung mass measuring point showed higher amplitude values ​​than the unsprung mass measuring point, and their phase-frequency values ​​were equal. This indicates a front suspension sprung mass resonance state. At this point, the amplitude ratio... =0.74.

[0060] Step 3: Adjust the amplitude ratio =0.74, resonant frequency of the sprung mass =2.85Hz, dynamic stiffness of single-side suspension spring Single-sided spring load Substituting 820kg into formula (2), the dynamic damping coefficient of the vehicle suspension on one side is obtained. .

[0061] In another implementation of this embodiment, also taking a single-sided suspension of a leaf spring suspension system as an example, the difference is that multiple tests were conducted to calculate the average amplitude ratio, thereby improving the accuracy of the measurement results. Figure 1 As shown, the specific measurement steps are as follows:

[0062] Step 1: Place unidirectional acceleration sensors on the unsprung mass and sprung mass parts of the front suspension. Select a straight section of a high-grade highway in the suburbs as the test road. To improve the accuracy of the test data and reduce adverse interference from external test conditions, the test road should meet the following requirements: the road surface slope is less than 1%, the unevenness is uniform without abrupt changes, and the road surface is dry during the test.

[0063] Step 2: Using vehicle speed as a characteristic parameter, the test is conducted under acceleration conditions. At a vehicle speed of 30km / h, local peak values ​​appear in the amplitude-frequency values ​​of the sprung mass measurement point and the unsprung mass measurement point in the direction perpendicular to the ground. At the same time, the sprung mass measurement point is greater than the unsprung mass measurement point and the phase-frequency values ​​are equal, indicating the front suspension sprung mass resonance state.

[0064] Step 3: Maintain a vehicle speed of 30 km / h for 10 sets of constant speed tests. Each test should be conducted in the same direction and on the same road segment to ensure the accuracy of the measurement data. Calculate the sprung mass resonance amplitude ratio based on the spectrum. .

[0065] Step 4: Substitute the 10 resonant amplitude ratios of the spring-loaded masses into the calculation formula (4); calculate the average amplitude ratio. =0.73.

[0066] Step 5: Adjust the average amplitude ratio =0.73, resonant frequency of the sprung mass =2.85Hz, dynamic stiffness of single-side suspension spring =800000 N / m, single-sided spring load Substituting 820kg into formula (3), the dynamic damping coefficient of the vehicle suspension on one side is obtained. .

[0067] Example 2

[0068] In another typical embodiment of the present invention, such as Figure 1 As shown, a vehicle suspension dynamic damping coefficient testing system is provided, comprising:

[0069] The parameter acquisition module is configured to: acquire the acceleration signals of the unsprung mass and the sprung mass, process them to identify the resonant frequency of the sprung mass, acquire the amplitude-frequency values ​​of the unsprung mass and the sprung mass, and calculate the amplitude ratio of the unsprung mass and the sprung mass.

[0070] The dynamic damping coefficient calculation module is configured to: establish a two-degree-of-freedom dynamic model of the suspension and obtain the dynamic differential equation; construct the vibration amplitude related quantity and equivalent relationship transmitted to the sprung mass after the vehicle suspension damping effect based on the differential equation; and calculate the dynamic damping coefficient of the vehicle suspension when the sprung mass resonates based on the equivalent relationship, combined with the amplitude ratio, sprung mass resonance frequency, suspension spring dynamic stiffness and sprung mass.

[0071] After identifying the resonant frequency of the sprung mass, record the rotational speed characteristic parameters at the sprung mass resonance.

[0072] Multiple rounds of uniform speed tests were conducted based on rotational speed characteristic parameters. The amplitude ratio of the unsprung mass and sprung mass parts in each round of test was recorded, and the average value was calculated and then substituted into the formula for calculating the dynamic damping coefficient.

[0073] The working method of the vehicle suspension dynamic damping coefficient testing system adopts the vehicle suspension dynamic damping coefficient testing method in Example 1, and will not be repeated here.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of testing a dynamic damping coefficient of a vehicle suspension, characterized by, include: The acceleration signals of the unsprung mass and the sprung mass are obtained, processed and the resonant frequency of the sprung mass is identified. The amplitude-frequency values ​​of the unsprung mass and the sprung mass are obtained, and the amplitude ratio of the unsprung mass and the sprung mass is calculated. A two-degree-of-freedom dynamic model of the suspension is established, and the dynamic differential equations are obtained. Based on the differential equations, the vibration amplitude correlation and equivalent relationship transmitted to the sprung mass after the vehicle suspension damping are constructed. Based on the equivalent relationship, combined with the amplitude ratio... Spring-loaded mass resonant frequency f Suspension spring dynamic stiffness k and sprung mass m The dynamic damping coefficient of the vehicle suspension at the sprung mass resonance was calculated through extrapolation and solution. c The calculation formula is as follows: ； in, ω is the angular frequency.

2. The method of claim 1, wherein, When the vehicle is traveling on a straight road, the acceleration signals of the unsprung mass and the sprung mass are acquired.

3. The vehicle suspension dynamic damping coefficient test method as described in claim 2, characterized in that, When the vehicle is in acceleration or coasting conditions, acquire the acceleration signals of the unsprung mass and the sprung mass.

4. The method of claim 1, wherein, The resonant frequency of the sprung mass identified after processing includes: The acceleration signal is subjected to spectral transformation, and the resonant phenomenon of the sprung mass is identified based on the spectrum, and the resonant frequency of the sprung mass is identified.

5. The vehicle suspension dynamic damping coefficient test method as described in claim 4, characterized in that, After identifying the resonant frequency of the sprung mass, record the rotational speed characteristic parameters at the sprung mass resonance. Multiple rounds of uniform speed tests were conducted based on rotational speed characteristic parameters. The amplitude ratio of the unsprung mass and sprung mass parts in each round of test was recorded, and the average value was calculated and then substituted into the formula for calculating the dynamic damping coefficient.

6. The method of claim 5, wherein, The speed characteristic parameter is one of the vehicle speed, engine speed in a certain gear, and drive shaft speed in a certain gear.

7. The method of claim 1, wherein, The acceleration signal consists of acceleration data of the unsprung mass and the sprung mass along the vertical direction of the ground.

8. The method of claim 1, wherein, The dynamic stiffness of the suspension springs was obtained through prior testing.

9. A vehicle suspension dynamic damping coefficient test system, characterized by, include: The parameter acquisition module is configured to: acquire the acceleration signals of the unsprung mass and the sprung mass, process them to identify the resonant frequency of the sprung mass, acquire the amplitude-frequency values ​​of the unsprung mass and the sprung mass, and calculate the amplitude ratio of the unsprung mass and the sprung mass. The dynamic damping coefficient calculation module is configured to: establish a two-degree-of-freedom dynamic model of the suspension and obtain the dynamic differential equation; based on the differential equation, construct the vibration amplitude correlation quantity and equivalent relationship transmitted to the sprung mass after the vehicle suspension damping effect; and based on the equivalent relationship, combine the amplitude ratio... Resonant frequency of the spring-loaded mass f Suspension spring dynamic stiffness k and sprung mass m The dynamic damping coefficient of the vehicle suspension at the sprung mass resonance was calculated through extrapolation and solution. c The calculation formula is as follows: ； wherein is the angular frequency.

10. The vehicle suspension dynamic damping coefficient test system of claim 9, wherein, After identifying the resonant frequency of the sprung mass, record the rotational speed characteristic parameters at the sprung mass resonance. Multiple rounds of uniform speed tests were conducted based on rotational speed characteristic parameters. The amplitude ratio of the unsprung mass and the sprung mass in each round of tests was recorded, and the average value was calculated and then substituted into the formula for calculating the dynamic damping coefficient.

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