A method for evaluating NVH attenuation performance of a vehicle chassis bushing

Abstract

The application discloses a kind of NVH attenuation performance evaluation methods of vehicle chassis bushing, obtain the Fs curve of three directions of durable bushing, the Fs curve of three directions is converted into the stiffness curve of three directions of durable bushing respectively;Durable bushing three directions stiffness is determined based on the stiffness curve of three directions of durable bushing;According to the stiffness of three directions of durable bushing and the stiffness of three directions of new bushing, the NVH attenuation performance of durable bushing is evaluated.The application divides bushing stress into radial solid direction, radial hollow direction and axial direction, and is converted into the stiffness of corresponding direction respectively, and the elasticity of bushing can be quantified and expressed directly by stiffness conversion, which is convenient for the stiffness attenuation of bushing, and the NVH attenuation performance of bushing is reflected by the stiffness attenuation of bushing, and then the NVH road noise attenuation performance of vehicle type can be quickly judged, which is simple and efficient, more accurate evaluation result, and also does not change the mileage of vehicle.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobiles, and particularly relates to a method for evaluating the NVH attenuation performance of a vehicle chassis bushing. BACKGROUND

[0002] With the increasingly perfect domestic automobile market, modern consumers have higher requirements for automobile performance and quality. New energy vehicles do not have traditional fuel engines, and the electric drive noise is relatively small as a whole, so the vehicle road noise contributes more and more to the overall comfort of the vehicle. As shown in the figure, the main excitation source of the vehicle road noise is the rough asphalt road exciting the tire through the chassis bracket path to cause the booming sound in the vehicle. The front bracket of the vehicle is connected to the triangular arm through the bushing, and the rear bracket is connected to the vehicle body through the bushing. Figure 9 The automobile bushing can reduce vibration and noise, significantly improve the comfort and driving experience of the vehicle, and plays a crucial role in improving the NVH performance of the vehicle. The NVH performance refers to noise (Noise), vibration (Vibration) and sound roughness (Harshness).

[0003] At present, the NVH attenuation performance of the bushing of a new vehicle placed for a long time is evaluated by driving the vehicle for a certain mileage, detecting the road noise in the vehicle during driving, and judging the NVH attenuation performance of the bushing according to the noise. This method changes the mileage of the vehicle. SUMMARY

[0004] The purpose of the present application is to solve the problems in the prior art and provide a method for evaluating the NVH attenuation performance of a vehicle chassis bushing.

[0005] The technical solution adopted by the present application is as follows: a method for evaluating the NVH attenuation performance of a vehicle chassis bushing, obtaining the Fs curves of the durability bushing in three directions, and converting the Fs curves in the three directions into the stiffness curves of the durability bushing in the three directions respectively.

[0006] Determining the stiffness of the durability bushing in three directions based on the stiffness curves of the durability bushing in the three directions.

[0007] Evaluating the NVH attenuation performance of the durability bushing according to the stiffness of the durability bushing in three directions and the stiffness of the new bushing in three directions.

[0008] Further, the Fs curves of the durability bushing in three directions are obtained through a bushing bench, and the three directions are radial hollow direction, radial solid direction and axial direction respectively.

[0009] Further, the process of converting the Fs curves in the three directions into the stiffness curves of the durability bushing in the three directions respectively is as follows:

[0010] The Fs curve is discretized according to the set distance resolution to obtain a plurality of discrete points, the stiffness of each discrete point is calculated, and the stiffness of all discrete points is fitted to obtain the stiffness curve.

[0011] Further, the stiffness of the discrete point is calculated by the following formula:

[0012] ;

[0013] Wherein, K i The stiffness of the i-th discrete point is, F i+1 The stress of the i+1-th discrete point is, F i The stress of the i-th discrete point is Δ s The set distance resolution is.

[0014] Further, before converting the stiffness curve of the radial hollow direction of the durable bushing, the point on the Fs curve of the radial hollow direction of the durable bushing where the stress fluctuation changes greater than a set threshold value is taken as an inflection point, the Fs curve of the radial hollow direction of the durable bushing is filtered based on the inflection point, and the range segment after the inflection point on the curve is filtered out, and the filtered Fs curve is taken as the basis for the conversion of the stiffness curve of the radial hollow direction of the durable bushing.

[0015] Further, the process of determining the stiffness of the three directions of the durable bushing based on the stiffness curves of the three directions of the durable bushing is:

[0016] The average value of the stiffness of all discrete points on the stiffness curve is calculated, and the average value is taken as the stiffness of the corresponding direction of the durable bushing.

[0017] Further, the process of evaluating the NVH attenuation performance of the durable bushing based on the stiffness of the three directions of the durable bushing and the stiffness of the three directions of the new bushing is:

[0018] The three directions of the durable bushing are divided by the three directions of the new bushing to obtain the improvement ratio of the three directions of the durable bushing, the total equivalent stiffness of the durable bushing is determined based on the improvement ratio and a set ratio, and the total equivalent stiffness of the durable bushing is compared with the total equivalent stiffness of the new bushing, and the NVH attenuation performance of the durable bushing is evaluated according to the comparison result.

[0019] Further, the total equivalent stiffness of the durable bushing is determined by the following formula:

[0020] ;

[0021] Wherein, K 总 The total equivalent stiffness of the durable bushing is, Ka 、 K b 、 K c The lifting ratio of the radial hollow direction, the radial solid direction and the axial direction of the durable bushing is respectively A, B and C, A, B and C are respectively the set ratio of the radial hollow direction, the radial solid direction and the axial direction of the durable bushing, and A+B+C is the total equivalent stiffness of the new bushing.

[0022] Further, the process of comparing the total equivalent stiffness of the durable bushing with the total equivalent stiffness of the new bushing and evaluating the NVH attenuation performance of the durable bushing according to the comparison result is as follows:

[0023] The total equivalent stiffness of the durable bushing is divided by the total equivalent stiffness of the new bushing to obtain an attenuation value, and the NVH attenuation performance of the durable bushing is evaluated according to the attenuation value.

[0024] Still further, the process of evaluating the NVH attenuation performance of the durable bushing according to the attenuation value is as follows:

[0025] If the attenuation value is less than a first set value, it is determined that the NVH attenuation performance of the durable bushing is good.

[0026] If the attenuation value is greater than or equal to the first set value and less than a second set value, it is determined that the NVH attenuation performance of the durable bushing is qualified.

[0027] If the attenuation value is greater than or equal to the second set value, it is determined that the NVH attenuation performance of the durable bushing is unqualified and the bushing needs to be replaced.

[0028] The beneficial effects of the present application are as follows:

[0029] The present application divides the force on the bushing into three directions of radial solid direction, radial hollow direction and axial direction, and converts them into stiffness in the corresponding directions, so that the elasticity of the bushing can be quantitatively and intuitively expressed through stiffness conversion, and the evaluation of the NVH attenuation performance of the bushing is facilitated.

[0030] The present application sets a proportion according to the different importance of road noise for the stiffness of the bushing in each direction, and performs proportioning and conversion according to the set proportion, compares the converted stiffness with the converted height of the new bushing, and evaluates the NVH attenuation through the proportioning and converted stiffness, so that the evaluation accuracy is higher.

[0031] The present application filters the Fs curve of the radial hollow direction of the durable bushing, filters out the range of the force fluctuation greater than the set threshold on the Fs curve, i.e. eliminates the part of the parameters that have no effect on road noise, and only uses the remaining parameters for stiffness curve conversion and calculation, so that the final evaluation result is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A flow chart of the present application.

[0033] Figure 2 A schematic diagram of a bush structure.

[0034] Figure 3 A Fs curve diagram (before filtering) of the radial hollow direction of the durable bush and the new bush of the present application.

[0035] Figure 4 A stiffness curve diagram (before filtering) of the radial hollow direction of the durable bush and the new bush of the present application.

[0036] Figure 5 A Fs curve diagram of the radial solid direction of the durable bush and the new bush of the present application.

[0037] Figure 6 A stiffness curve diagram of the radial solid direction of the durable bush and the new bush of the present application.

[0038] Figure 7 A Fs curve diagram of the axial direction of the durable bush and the new bush of the present application.

[0039] Figure 8 A stiffness curve diagram of the axial direction of the durable bush and the new bush of the present application.

[0040] Figure 9 A schematic diagram of the transmission relationship of road noise and road, tire, and bush. DETAILED DESCRIPTION

[0041] The specific embodiments of the present application will be further described below with reference to the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present application, but does not constitute a limitation on the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0042] As shown in Figure 1 The present application provides a method for evaluating the NVH attenuation performance of a vehicle chassis bush, obtaining the Fs curve of the durable bush in three directions, and converting the Fs curve in three directions into the stiffness curve of the durable bush in three directions. The Fs curve of the bush, i.e. the Force-Displacement curve, is a curve drawn by the press-in force and the press-in displacement data collected during the press-fitting process, which reflects the stress and deformation of the bush during the press-fitting process.

[0043] Based on the stiffness curve of the durable bush in three directions, the stiffness of the durable bush in three directions is determined.

[0044] The NVH attenuation performance of the durable bushing is evaluated according to the stiffness of the durable bushing in three directions and the stiffness of the new bushing in three directions.

[0045] The Fs curves of the bushing in three directions are converted into the stiffness of the corresponding direction respectively, the stiffness conversion can quantitatively and intuitively express the elasticity of the bushing, and the NVH attenuation performance of the bushing is convenient to evaluate; the stiffness attenuation of the bushing is evaluated by comparing the stiffness of the durable bushing with the stiffness of the new bushing, the stiffness attenuation of the bushing reflects the NVH attenuation performance of the bushing, and then the NVH road noise attenuation performance of the vehicle model can be quickly judged, the method is simple and efficient, the evaluation result is more accurate, and at the same time, the mileage of the vehicle is not changed.

[0046] In the above scheme, the Fs curves of the durable bushing (i.e. the durable sample) and the new bushing (the new sample) in three directions are obtained through the bushing test bench, and the three directions are respectively the radial hollow direction, the radial solid direction and the axial direction, as shown in Figure 3 、 Figure 5 、 Figure 7 The Fs curves of the radial hollow direction, the radial solid direction and the axial direction of the bushing are shown.

[0047] In the above scheme, the process of converting the Fs curves in three directions into the stiffness curves of the durable bushing in three directions is: the Fs curves are discretized to obtain a plurality of discrete points according to the set distance resolution, the stiffness of each discrete point is calculated, and the stiffness of all discrete points is fitted to obtain the stiffness curve, and the converted stiffness curve is shown in Figure 4 、 Figure 6 、 Figure 8 The set distance resolution is set according to the structure size of the bushing, and the range can be set to 0.02mm-0.1mm, and the preferred value in the embodiment is 0.02mm or 0.03mm or 0.04mm or 0.05mm.

[0048] In the above scheme, the stiffness of the discrete point is calculated by the following formula:

[0049] ;

[0050] Wherein, K i The stiffness of the i-th discrete point is F i+1 The stress of the i+1-th discrete point is F i The stress of the i-th discrete point is Δ s The set distance resolution is Δ.

[0051] The vehicle chassis bushing includes a triangular arm rear bushing and a rear bracket front and rear bushing, and the Fs curve of the bushing generally presents a smooth growth trend, but the radial direction of the bushing has an opening, as shown inFigure 2 As shown, when force is applied, there will be a mutation, resulting in an inflection point of the Fs curve, as shown in the figure Figure 3 As shown, the range segment after the inflection point is caused by the large deformation of the bushing due to the opening, and the curve in this range does not reflect the actual stress deformation of the bushing, so the range segment after the inflection point is not involved in the subsequent stiffness calculation. The processing is that, before converting the stiffness curve of the radial hollow direction of the durable bushing, the point where the stress fluctuation of the Fs curve of the radial hollow direction of the durable bushing is greater than the set threshold is taken as the inflection point, the Fs curve of the radial hollow direction of the durable bushing is filtered based on the inflection point, and the range segment after the inflection point is filtered out. The Fs curve after filtering is used as the basis for the conversion of the stiffness curve of the radial hollow direction of the durable bushing.

[0052] The present application filters the Fs curve of the radial hollow direction of the durable bushing, filters out the range segment where the stress fluctuation is greater than the set threshold, i.e. eliminates the part of the parameter that has no effect on road noise, and only uses the remaining parameter to convert and calculate the stiffness curve, so that the final evaluation result is more accurate.

[0053] In the above scheme, the process of determining the stiffness of the durable bushing in three directions based on the stiffness curves of the durable bushing in three directions is: calculating the average value of the stiffness of all discrete points on the stiffness curve, and taking the average value as the stiffness of the corresponding direction of the durable bushing. The average value of the stiffness of each point on the bushing stiffness curve is taken as the stiffness of the corresponding direction, which can better reflect the stiffness level of the bushing when subjected to torsional force.

[0054] In the above scheme, the process of evaluating the NVH attenuation performance of the durable bushing according to the stiffness of the durable bushing in three directions and the stiffness of the new bushing in three directions is: dividing the stiffness of the durable bushing in three directions by the stiffness of the new bushing in three directions to obtain the improvement ratio of the durable bushing in three directions, determining the total equivalent stiffness of the durable bushing based on the improvement ratio and the set ratio, comparing the total equivalent stiffness of the durable bushing with the total equivalent stiffness of the new bushing, and evaluating the NVH attenuation performance of the durable bushing according to the comparison result. The stiffness of the bushing in each direction is set according to the different importance of road noise, and the equivalent stiffness is calculated according to the set ratio, and the equivalent stiffness is compared with the equivalent height of the new bushing, and the attenuation is evaluated by the equivalent stiffness, so that the evaluation accuracy is higher.

[0055] In the above scheme, the total equivalent stiffness of the durable bushing is determined by the following formula:

[0056] ;

[0057] Wherein, K 总 The total equivalent stiffness of the durable bushing is K a ,K b 、 K c The improvement ratios of the durability bushing in the radial hollow direction, the radial solid direction and the axial direction are A, B and C respectively, A, B and C are the set ratios of the durability bushing in the radial hollow direction, the radial solid direction and the axial direction, equal to the contribution amount in the corresponding direction multiplied by one hundred, that is, the total equivalent stiffness of the new bushing is calculated as 100, and A+B+C=100. The final calculation of the application is carried out by using the equivalent stiffness, and the calculation process is more convenient and fast.

[0058] The stiffness results of the three directions of the chassis bushing are different in size, and the importance of road noise is also different, among which the axial direction stiffness is the most important, but its value is the smallest, the radial hollow direction is the second important, and the radial solid direction is the third important. According to the importance, the allocation method of 60%, 25% and 15% can be used, that is, A=25, B=15 and C=60, according to the product demand, other allocation ratios can also be set, and the calculation results are shown in Table 1. The improvement ratio in Table 1 is the corresponding direction stiffness of the durability bushing divided by the stiffness of the corresponding direction of the new bushing, the contribution amount is the importance of the three directions to the road noise, and the set ratio according to the contribution amount can more accurately represent the correlation between the stiffness attenuation of the bushing and the vehicle NVH road noise.

[0059] Table 1: Calculation table of vehicle durability bushing stiffness.

[0060] .

[0061] The total equivalent stiffness of the above-mentioned durability bushing and the total equivalent stiffness of the new bushing are compared, that is, the total equivalent stiffness of the durability bushing is divided by the total equivalent stiffness of the new bushing, and the attenuation value is obtained. According to the attenuation value, the NVH attenuation performance of the durability bushing is evaluated:

[0062] If the attenuation value is less than the first set value, it is determined that the NVH attenuation performance of the durability bushing is good;

[0063] If the attenuation value is greater than or equal to the first set value and less than the second set value, it is determined that the NVH attenuation performance of the durability bushing is qualified;

[0064] If the attenuation value is greater than or equal to the second set value, it is determined that the NVH attenuation performance of the durability bushing is unqualified, and the bushing needs to be replaced.

[0065] The first set value and the second set value are calibrated according to the actual demand. In this embodiment, the first set value is set as 10%, and the second set value is set as 28%. Therefore, the final calculated attenuation value is between 0-10% to determine good, 10-28% to determine qualified, and more than 28% to determine that the part needs to be replaced.

[0066] Through the above evaluation process, for the vehicle placed overseas for a long time, the bushing of a single vehicle can be analyzed, and the attenuation performance of the bushing NVH of all vehicles in the batch can be determined, so that the NVH road noise performance of all vehicles can be quickly judged. This method is simple, efficient and highly reliable.

[0067] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

Claims

1. A method for evaluating the NVH (Noise, Vibration, and Harshness) degradation performance of vehicle chassis bushings, characterized in that: Obtain the Fs curves of the durability bushing in three directions, and convert the Fs curves in the three directions into stiffness curves of the durability bushing in the three directions respectively. The stiffness of the durability bushing in three directions is determined based on the stiffness curves of the durability bushing in three directions. The NVH degradation performance of the durable bushing is evaluated based on the stiffness of the durable bushing in three directions and the stiffness of the new bushing in three directions. The process of evaluating the NVH degradation performance of the durable bushing based on the stiffness of the durable bushing in three directions and the stiffness of the new bushing in three directions is as follows: The three directions are the radial hollow direction, the radial solid direction, and the axial direction. The stiffness of the durable bushing in the three directions is divided by the stiffness of the new bushing in the three directions to obtain the improvement ratio of the durable bushing in the three directions. Based on the improvement ratio and the set ratio, the total equivalent stiffness of the durable bushing is determined. The total equivalent stiffness of the durable bushing is compared with the total equivalent stiffness of the new bushing, and the NVH attenuation performance of the durable bushing is evaluated based on the comparison results.

2. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 1, characterized in that: The Fs curves of the durable bushing in three directions were obtained using a bushing test bench.

3. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 1, characterized in that, The process of converting the Fs curves in the three directions into stiffness curves in the three directions of the durability bushing is as follows: The Fs curve is discretized according to the set distance resolution to obtain several discrete points. The stiffness of each discrete point is calculated, and the stiffness of all discrete points is fitted to obtain the stiffness curve.

4. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 3, characterized in that, The stiffness of discrete points is calculated using the following formula: ； in, Let be the stiffness of the i-th discrete point. Let i be the magnitude of the force at the (i+1)th discrete point. Let be the magnitude of the force at the i-th discrete point. To set the distance resolution.

5. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 3, characterized in that: Before converting the stiffness curve of the radial hollow direction of the durable bushing, the point on the Fs curve of the radial hollow direction of the durable bushing where the force fluctuation change is greater than a set threshold is taken as the inflection point. The Fs curve of the radial hollow direction of the durable bushing is filtered based on the inflection point to remove the range segment on the curve after the inflection point. The conversion of the stiffness curve of the radial hollow direction of the durable bushing is then performed based on the filtered Fs curve.

6. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 1, characterized in that, The process of determining the stiffness of the durability bushing in three directions based on the stiffness curves of the durability bushing in three directions is as follows: Calculate the average stiffness of all discrete points on the stiffness curve, and use the average value as the stiffness of the corresponding direction of the durable bushing.

7. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 1, characterized in that, The total equivalent stiffness of the durability bushing is determined using the following formula: ； in, The total equivalent stiffness of the durable bushing. , , These represent the lifting ratios in the radial hollow direction, radial solid direction, and axial direction of the durable bushing, respectively. A, B, and C are the set ratios in the radial hollow direction, radial solid direction, and axial direction of the durable bushing, respectively. A+B+C = the total equivalent stiffness of the new bushing.

8. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 1, characterized in that, The process of comparing the total equivalent stiffness of the durable bushing with that of the new bushing, and evaluating the NVH degradation performance of the durable bushing based on the comparison results, is as follows: Divide the total equivalent stiffness of the durable bushing by the total equivalent stiffness of the new bushing to obtain the attenuation value. Evaluate the NVH attenuation performance of the durable bushing based on the attenuation value.

9. The method for evaluating the NVH degradation performance of vehicle chassis bushings according to claim 8, characterized in that, The process of evaluating the NVH degradation performance of the durability bushing based on the degradation value is as follows: If the attenuation value is less than the first set value, then the NVH attenuation performance of the durability bushing is determined to be good. If the attenuation value is greater than or equal to the first set value and less than the second set value, then the NVH attenuation performance of the durability bushing is deemed qualified. If the attenuation value is greater than or equal to the second set value, the NVH attenuation performance of the durability bushing is determined to be unqualified, and the bushing needs to be replaced.

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