NVH evaluation method for ball screw based on order bandwidth monitoring

Abstract

A ball screw NVH evaluation method based on order bandwidth monitoring includes a drive motor connected to the ball screw and driven to rotate, the ball screw includes at least one of a rolling element, a nut and a screw, and the ball screw is detected according to the following steps: Step 1: The drive motor drives the ball screw to rotate at a constant speed, and collects vibration signals in the clamping stage and the release stage of the ball screw respectively; Step 2: Calculate and process the collected vibration signals according to one or more of time domain analysis, frequency domain analysis and order analysis; Step 3: Output one or more charts in step 2. The beneficial effect of the present invention is that a variety of analysis methods can effectively cover the NVH performance of the ball screw as a whole and each component, which is convenient for manufacturing enterprises to timely optimize each component in a targeted manner according to the parameter standards required by the user combined with the NVH performance obtained by each component, thereby effectively reducing the R&D cost.

Description

Technical Field

[0001] The invention relates to a testing method, and in particular to a ball screw NVH evaluation method based on order bandwidth monitoring. Background Art

[0002] NVH performance refers to the noise, vibration and harshness of a car during driving. It is directly related to the comfort of drivers and passengers and is one of the important indicators for measuring vehicle quality and market competitiveness. The evaluation of NVH performance includes the use of test equipment such as sound level meters, vibration meters, and data collectors, as well as testing methods such as environmental tests and durability tests. In addition, the improvement of NVH performance is not only related to the comfort of drivers and passengers, but also an important indicator for measuring vehicle quality and market competitiveness.

[0003] A ball screw is a mechanical component used to convert rotational motion into linear motion. In vehicle systems, a ball screw may be used in a variety of different applications, such as electric power steering systems (EPS), seat adjustment systems, sunroof adjustment systems, etc. Therefore, its NVH performance will directly affect the NVH performance of the entire vehicle.

[0004] Chinese patent document CN115796705B discloses a NVH grading evaluation method for an electric drive assembly of a new energy vehicle, comprising the following steps: S1, NVH data collection and preprocessing of the electric drive assembly; S2, NVH data statistics of the electric drive assembly; S3, establishing an NVH grading evaluation system for the electric drive assembly based on the characteristic indicators and statistical results obtained in step S2; S4, determining the evaluation score of each indicator based on the result data value of each evaluation indicator; S5, based on the evaluation results in steps S3 and S4, performing data verification on the NVH evaluation results of the electric drive assembly to determine the correctness of the grading method.

[0005] The above scheme can find noteworthy data ranges from a large range of statistical results and further evaluate the data range to analyze the NVH performance in the range. However, the above scheme has the following shortcomings: the existing scheme can only find a few key data ranges and evaluate and re-test them to confirm the correctness of the data. However, since the data cannot be matched with parts, the existing scheme can only be used to test finished product data and has no guiding significance for the direction of improvement. This forces manufacturing companies to conduct inspections after producing finished product samples, which will rapidly increase the cost of improving their own products, resulting in cost waste. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a ball screw NVH evaluation method based on order bandwidth monitoring which is more targeted and more instructive for manufacturing enterprises.

[0007] To achieve the above object, the technical solution of the present invention is as follows: a ball screw NVH evaluation method based on order bandwidth monitoring, including a drive motor connected to the ball screw and driving it to rotate, the ball screw including at least one of a rolling element, a nut and a screw, characterized in that the ball screw is detected according to the following steps:

[0008] Step 1: Use a driving motor to drive the ball screw to rotate at a constant speed, and collect vibration signals of the ball screw in the clamping stage and the release stage respectively;

[0009] Step 2: Calculate and process the collected vibration signal according to one or more of time domain analysis, frequency domain analysis and order analysis;

[0010] Step 2.a (Time Domain Analysis): Calculate the overall noise level of the ball screw;

[0011] Step 2.b (frequency domain analysis): After distinguishing the frequency bands, calculate the noise level of the ball screw as a whole in each frequency band;

[0012] Step 2.c (Order Analysis): After distinguishing the order bandwidth of each component of the ball screw, calculate the noise level of at least one component among the rolling element, nut and screw in the ball screw;

[0013] Step 3: Output one or more of the graphs in Step 2.a, Step 2.b, and Step 2.c.

[0014] Furthermore, in step 1, a data collector is also included, and the ball screw also includes a reverser for forming a rolling body circulation, and the data collector is arranged to form an angle of 90° with the reverser.

[0015] Furthermore, in step 1, one end of the ball screw is always subjected to a constant axial load during the process of collecting vibration signals.

[0016] Furthermore, it is characterized in that: in step 2.a, the calculation process is implemented by RMS calculation, and the formula is as follows:

[0017] .

[0018] Furthermore, in step 2.b, three frequency bands, namely low frequency, medium frequency and high frequency, are selected through FFT transformation, and the noise level in each frequency band is calculated through RMS calculation. The calculation formula is as follows:

[0019] .

[0020] Furthermore, the frequency bandwidths of the frequency bands in step 2.b are respectively 10-500 Hz for low frequency, 500-1200 Hz for medium frequency, and 1200-4500 Hz for high frequency.

[0021] 1. Furthermore, the process of processing the original signal in step 2.c is as follows: c.1 performing a 6th-order Butterworth filter on the original signal;

[0022] c.2 Use Hilbert transform to perform envelope analysis on the filtered signal;

[0023] c.3 Perform FFT transformation on the filtered signal in c.2 to obtain a frequency spectrum of at least one of the rolling element, nut and screw in the ball screw;

[0024] c.4 Calculate the order bandwidth of each component

[0025] c.5 Perform RMS calculation.

[0026] Furthermore, the order bandwidth in c.4 is calculated as follows: order bandwidth = characteristic frequency of each component itself / screw rotation frequency.

[0027] Furthermore, the formula for calculating RMS in c.5 is as follows:

[0028] .

[0029] The beneficial effects of the present invention include at least the following points.

[0030] A variety of analysis methods can effectively cover the NVH performance of the ball screw as a whole and each component, making it easy for manufacturing companies to optimize each component in a targeted manner based on the parameter standards required by users and the NVH performance of each component, thereby effectively reducing R&D costs.

[0031] Secondly, if the NVH performance of only one or several components is not ideal while most components meet the standards, the order analysis method in this scheme can be used to carry out targeted testing on the replaced one or several components to confirm the optimization effect, so as to further reduce the R&D cost. That is, the present invention can effectively eliminate the interference of other components in the ball screw, facilitate the discovery of problematic components and effective improvement of such components.

[0032] Furthermore, the NVH evaluation scheme used in the present invention makes it possible for users to propose specific parameter standards for each component, thereby making manufacturing companies more competitive than other competitors in the same industry.

[0033] In addition, during the ball screw detection process, the clamping stage is the screw-out stage of the ball screw, and the release stage is the screw-in stage of the ball screw; and in this process, a constant axial load is applied to the guide of the ball screw in the direction opposite to the screw-in and screw-out direction of the ball screw, which can be used to simulate the actual working environment of the ball screw to obtain parameters that are closer to the actual environment. At the same time, during the entire detection process, the data collector, that is, the acceleration sensor, is set at a position 90° from the reverser to facilitate real-time detection of radial vibration signals when the ball screw moves.

[0034] In addition, since the calculation of the order bandwidth is based on the ratio between the characteristic frequency of each component and the main shaft rotation frequency, the present invention can be used to test the NVH performance of more ball screws in actual working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is an axonometric view of a ball screw according to an embodiment of the present invention;

[0036] Figure 2 is a cross-sectional view of a ball screw according to an embodiment of the present invention;

[0037] Figure 3 A flow chart of time domain analysis according to an embodiment of the present invention;

[0038] Figure 4 This is an original vibration signal diagram of an embodiment of the present invention;

[0039] Figure 5 A noise level curve diagram obtained based on time domain analysis according to an embodiment of the present invention;

[0040] Figure 6 A flowchart of frequency domain analysis according to an embodiment of the present invention;

[0041] Figure 7 This is a spectrum diagram obtained based on frequency domain analysis according to an embodiment of the present invention;

[0042] Figure 8 is a flow chart of order analysis according to an embodiment of the present invention;

[0043] Fig. 9 It is an order spectrum obtained based on order analysis under low-frequency filtering according to an embodiment of the present invention;

[0044] Fig.10 It is an order spectrum obtained based on order analysis under intermediate frequency filtering according to an embodiment of the present invention;

[0045] Fig.11 It is a standard diagram of parameters in the clamping stage of an embodiment of the present invention;

[0046] Fig.12 This is a standard diagram of parameters in the release phase of an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention provides a method for evaluating NVH of a ball screw based on order bandwidth monitoring. Figure 1-12 As shown in the figure, the ball screw used for detection mainly includes a screw 1, a guide tube 2, a rolling element 3, a nut 4, a friction plate 5, a large elastic retaining ring 6, a buffer ring 7, a small elastic retaining ring 8, a gasket 9 and a reverser 10. It should be noted that in this embodiment Fig.10 and Fig.11 The parameter standards can be changed according to the needs of the user or the research and development standards of the enterprise, and are not limited to the parameter standards provided in the drawings. The specific parameters in other drawings are obtained by combining other parameters in this embodiment, and it does not mean that the present invention must be limited to these parameters.

[0048] The NVH evaluation method includes the following steps:

[0049] Step 1: In this embodiment, the driving motor drives the ball screw to rotate at a constant speed of 700 rpm, and applies a constant axial load of 2KN at one end of the guide, which can be achieved by a pressure member such as a cylinder or an oil cylinder. At the same time, a data collector is set at a position where the reverser 10 forms a 90° angle with the reverser 10. In this embodiment, the data collector is an acceleration sensor, which is used to detect the radial vibration signal of the ball screw (i.e., the Z direction) in real time.

[0050] Step 2: The original signal is processed by one or more of time domain analysis, frequency domain analysis and order analysis. In this embodiment, three analysis methods, namely time domain analysis, frequency domain analysis and order analysis, are shown:

[0051] Step 2.a, that is, the analysis method of time domain analysis is as follows: directly process the original signal through RMS calculation, and the formula is as follows:

[0052] .

[0053] Step 2.b, i.e. the analysis method of frequency domain analysis is as follows: b.1 Perform spectrum signal analysis through FFT transformation, and divide the frequency domain signal into low frequency 10-500Hz, medium frequency 500-1200Hz, and high frequency 1200-4500Hz; b.2 Perform RMS calculation processing on the signal in each frequency band, and the formula is as follows:

[0054] .

[0055] Step 2.c, i.e., the analysis method of order analysis is as follows: c.1 The original signal is subjected to 6th-order Butterworth filtering. After filtering, it is found that the signal in the high-frequency band is relatively weak and has no analysis value in this embodiment. Therefore, the output chart of the high-frequency band is not shown in this embodiment;

[0056] c.2 Use Hilbert transform to perform envelope analysis on the filtered signal;

[0057] c.3 Perform FFT transformation on the filtered signal in c.2 to obtain the frequency spectrum of each component in the ball screw. In this embodiment, only the nut 4, the screw 1 and the rolling element 3 are analyzed, but this method is not limited to these three parts in the ball screw;

[0058] c.4 The order bandwidth of the nut 4, screw 1 and rolling element 3 can be obtained by the ratio between the rotation speed of the ball screw at 700 rpm and the characteristic frequencies of the various components, namely, the nut 4, screw 1 and rolling element 3 in this embodiment. Figure 8 , Fig.10 and Fig.11 c.5 RMS calculation is performed for each order bandwidth, and the calculation formula is as follows:

[0059] .

[0060] Step 3: Output charts based on the data obtained from time domain analysis, frequency domain analysis, and order analysis.

[0061] The above embodiment is only one of the preferred specific embodiments of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A ball screw NVH evaluation method based on order bandwidth monitoring, comprising a drive motor connected to a ball screw and driving the ball screw to rotate, wherein the ball screw comprises at least one of a rolling element, a nut and a screw, and is characterized in that: The ball screw is tested according to the following steps: Step 1: driving the ball screw to rotate at a constant speed by a driving motor, and collecting vibration signals of the ball screw in the clamping stage and the release stage respectively; Step 2: Calculate and process the collected vibration signal according to time domain analysis, frequency domain analysis and order analysis; Step 2.a: Calculate the overall noise level of the ball screw through time domain analysis; Step 2.b: Distinguish the frequency bands through frequency domain analysis and calculate the overall noise level of the ball screw in each frequency band; Step 2.c: Calculate the noise level of the rolling element, nut and screw in the ball screw by distinguishing the order bandwidth of each component of the ball screw through order analysis; Step 3: Output the graphs for Step 2.a, Step 2.b, and Step 2.c.

2. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 1 is characterized in that: In step 1, a data collector is also included, and the ball screw also includes a reverser for forming a rolling body circulation, and the data collector is arranged to form an angle of 90° with the reverser.

3. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 2 is characterized in that: In step 1, one end of the ball screw is always subjected to a constant axial load during the process of collecting vibration signals.

4. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 1 is characterized in that: In step 2.a, the calculation process is implemented through RMS calculation, and the formula is as follows: 。 5. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 4 is characterized in that: In step 2.b, the low frequency, medium frequency and high frequency bands are screened out through FFT transformation, and the noise level in each frequency band is calculated by RMS calculation. The calculation formula is as follows: 。 6. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 5 is characterized in that: The frequency bandwidths of the frequency bands in step 2.b are respectively 10-500 Hz for low frequency, 500-1200 Hz for medium frequency, and 1200-4500 Hz for high frequency.

7. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 4 is characterized in that: The process of processing the original signal in step 2.c is as follows: c.1 performing 6th order Butterworth filtering on the original signal; c.2 Use Hilbert transform to perform envelope analysis on the filtered signal; c.3 Perform FFT transformation on the signal after envelope analysis in c.2 to obtain a frequency spectrum of at least one of the rolling element, nut and screw in the ball screw; c.4 Calculate the order bandwidth of each component; c.5 Perform RMS calculation.

8. The ball screw NVH evaluation method based on order bandwidth monitoring according to claim 7 is characterized in that: The order bandwidth in c.4 is calculated as follows: order bandwidth = characteristic frequency of each component / screw rotation frequency.

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