CN101871846A - An On-line Detection Method of Torsional Vibration Signal of Automobile Power Transmission System - Google Patents

Abstract

The invention relates to an on-line detection method for torsional vibration signals of an automobile power transmission system, belonging to the field of automobile noise and vibration control. According to the method, the torsional vibration is tested and analyzed on the power transmission system of the front and rear drive independent suspension vehicle of the running vehicle. Install the test gear plate and speed sensor at the measured position of the power transmission system, measure the rotation signal of the power transmission system, perform adaptive filtering on it, and perform time-frequency analysis on the filtered signal to calculate the torsional vibration frequency of the system. This method is used to test and analyze the torsional vibration of the actual vehicle, especially the acceleration driving condition of the front and rear drive independent suspension vehicle, without the need to establish a torsional vibration test bench. Install the test tooth plate and speed sensor at the measured position of the power transmission system, measure the rotation signal of the power transmission system, calculate the instantaneous speed through peak detection, and filter it, and calculate the torsional vibration frequency of the system through time-frequency analysis of the filtered signal .

Description

An On-line Detection Method of Torsional Vibration Signal of Automobile Power Transmission System

technical field

The invention relates to an on-line detection method for torsional vibration signals of an automobile power transmission system, in particular for performing torsional vibration testing and analysis on the power transmission system of a front-rear drive independent suspension vehicle, and belongs to the field of automobile noise and vibration control.

Background technique

The vehicle power transmission system is a complex, multi-degree-of-freedom vibration system, which is an important excitation source of vehicle vibration and noise. Among them, torsional vibration is one of the basic vibration forms of the power transmission system. For a vehicle with a front engine, rear wheel drive, and independent suspension structure, the power of the engine is transmitted to the rear of the vehicle through the transmission shaft. Due to the long distance of power transmission, the probability of torsional vibration during the transmission process increases; The main reducer of the vehicle with rear independent suspension structure is directly connected to the vehicle body, so the torsional vibration of the power transmission system is directly transmitted to the vehicle body, which seriously affects the ride comfort of the vehicle and generates relatively large interior noise.

For the vibration and noise problems caused by the torsion of the power transmission system, the torsional vibration experiment of the power transmission system can be used to test and analyze the torsional vibration characteristics of the engine crankshaft and the rotating shaft of the transmission system. According to the obtained excitation and response characteristics of the torsional vibration of the system, the torsional resonance of the power transmission system and the main position and frequency characteristics of the torsional resonance of the system are analyzed.

The torsional vibration measurement of the rotating shaft system can be divided into contact type and non-contact type. The purpose of the torsional vibration test of the vehicle power transmission system is to analyze the main position and frequency characteristics of the torsional resonance of the system, and does not involve the stress or deformation of the shaft system. , it is advisable to use non-contact torsional vibration test method, in the test analysis, the method of simulation and experimental bench is often used to analyze the torsional vibration of the vehicle power transmission system (Guo Lei, Research on the Dynamic Vibration Characteristics of the Gear Transmission System of Automobile Transmission, Vibration and Shock, 2010; Ming Zhangjie, Research on Torsional Vibration of Shafting of a Locomotive Diesel Generator Set Based on 3D Solid Finite Element, Diesel Engine, 2008). For the rotation signal of the power transmission system under acceleration conditions, the frequency fluctuation range is wide, and it is difficult to achieve the expected effect by using traditional testing and analysis methods, and the distortion principle of the measured torsion signal is intricate, and most of them are accompanied by randomness, so it is difficult to accurately identify . Therefore, how to accurately and effectively measure and analyze the torsional vibration of the power transmission system under actual vehicle acceleration conditions is the key to improving vehicle vibration and noise.

Contents of the invention

The object of the present invention is to propose an on-line detection method for torsional vibration signals of an automobile power transmission system, which does not require a bench test of the torsional vibration system. Carry out torsional vibration test and analysis directly on the actual driving vehicle, especially the power transmission system of the front and rear drive independent suspension vehicle. Install the test gear plate and speed sensor at the measured position of the power transmission system, measure the rotation signal of the power transmission system, perform adaptive filtering on it, and perform time-frequency analysis on the filtered signal to calculate the torsional vibration frequency of the system.

The on-line detection method of the torsional vibration signal of the automobile power transmission system proposed by the present invention comprises the following steps:

(1) Install the test tooth plate on the rotating part of the power transmission system of the vehicle under test, the test tooth plate and the rotating part are fixed coaxially, and a speed sensor is fixed on the car body or the casing of the rotating part, and the speed sensor is in the test position. On the side of the gear plate, when the vehicle under test accelerates, the rotation signal of the rotating part is collected;

(2) Assuming that the i-th peak value of the rotation signal s(t) of the rotating member appears at the time t _peak (i), then the time period T during which the i-th tooth on the tooth plate corresponding to the i-th peak value sweeps across the speed sensor is tested (i) is:

T(i)＝t _peak (i+1)-t _peak (i)

According to the time period T(i) of the i-th tooth, calculate the time period of the i+1-th tooth as T(i+1), the value of T(i+1)

0＜α＜1，0＜β＜1，在上述取值范围内检索旋转信号的峰值点，得到第i+1个齿的时间周期T(i+1)，依次递推得到测试齿盘上所有齿的时间周期；The range is: αT(i)<T(i+1)<(α+β)T(i), where α and β are periodic coefficients, and α and β satisfy:

0<α<1, 0<β<1, search the peak point of the rotation signal within the above value range, get the time period T(i+1) of the i+1th tooth, and then recursively get the the time period of all teeth;

According to the above time period of all teeth, the instantaneous speed of each tooth is obtained as:

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}$

According to the instantaneous rotational speed of all the teeth above, the average rotational speed of the rotating part is obtained as:

$\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; Z</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>$

Where Z is the number of teeth of the test chainring;

(3) According to the average rotational speed of the above-mentioned rotating parts, the center frequency f _c (t _i ) of the band-pass filter used to filter the instantaneous rotational speed is obtained as:

According to the center frequency of the above-mentioned band-pass filter, the time-discrete form of the windowed impulse response function of the band-pass filter is obtained as:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, r is the bandwidth of the bandpass filter, r=β, T _d is the group delay, T _d =N/2F _s , F _s is the sampling frequency of the rotation signal of the rotating part, w _β [t _k ] is the raised cosine window function, [t _k ] is the sampling time series, [t _k ]=k/F _s , (k=0, 1,..., N-1), N is the length of the filter function, N=K/60, K is the the length of the filtered signal;

(4) Linearly interpolate the above-mentioned instantaneous speed n(t _i ) according to the above-mentioned sampling time series [t _k ] to obtain the time-discrete form n[t _k ] of the instantaneous speed, and use the above-mentioned windowed impulse response function h _β [t _k ] to filter the time-discrete form n[t _k ] of the instantaneous speed, and obtain the filtered instantaneous speed of the rotating part as:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>$

The rotation signal collected by the car under test during the entire acceleration process is divided into segments according to the data length of each rotation of the test toothed disc, and steps (2), (3) and (4) are repeated to filter each segment of the signal to obtain the measured Measure the instantaneous speed n _s-all [t _k ] of the rotating parts during the whole acceleration process of the vehicle;

(5) Transform the instantaneous rotational speed _{n s-all} [t _k ] of the rotating parts of the vehicle under test during the entire acceleration process into the frequency domain instantaneous rotational speed n _s (t _p , f) through short-time Fourier transform, where t _p is the moment when the short-time Fourier transform is performed, and the value range of t _p is t _start ≤ t _p ≤ t _end , t _start is the starting moment of the acceleration of the measured vehicle, and t _end is the end of the acceleration of the measured vehicle time, f is the frequency of the instantaneous speed in the frequency domain;

According to the average rotational speed v(t _i ) of the above-mentioned rotating parts, the order frequency of each order of rotating parts is obtained as:

f _m (t _i )=m·v(t _i )

Among them, m is the order;

According to the rotational speed order frequency f _m (t _i ) of each order of the rotating member calculated above, the frequency-domain instantaneous rotational speed n _s (t _p , f) is converted into the order instantaneous rotational speed n _sm [f _m (f _p )] , where f _m (t _p ) is the speed order frequency of the mth order instantaneous speed at time t _p ;

Retrieve the m-th order instantaneous speed n _sm [f _m (t _p )] of the measured vehicle during the entire acceleration process, and obtain the maximum value max{n _sm [f _m (t p )] of this order instantaneous speed _p )]}, the speed order frequency f _m-max (t _p-max ), that is, the order frequency of the torsional vibration signal of the mth order of the rotating part is:

f _m =f _m-max (t _p-max )

Among them, t _p-max is the moment when the maximum value of the instantaneous rotational speed of the mth order of the rotating member appears.

The online detection method of the torsional vibration signal of the automobile power transmission system proposed by the present invention has the advantages of:

1. The online detection method of the present invention does not need to set up a torsional vibration test bench, and does not need to arrange the power transmission system on the bench according to the actual vehicle structure, and directly takes the actual vehicle power transmission system as the test object, which simplifies the test steps and equipment;

2. The on-line detection method of the present invention can test the torsional vibration situation of the power transmission system of the vehicle under test under actual acceleration driving conditions;

3. The online detection method of the present invention can reduce the influence of rotational speed distortion caused by the vibration of the vehicle, improve the analysis accuracy, and accurately calculate the torsional vibration frequency of the power transmission system.

Description of drawings

Fig. 1 is a schematic structural diagram of a test system used when using the online detection method proposed by the present invention.

Figure 2 is a structural diagram of the test toothed disc.

Figure 3 is a schematic diagram of peak detection.

Detailed ways

The on-line detection method of the torsional vibration signal of the automobile power transmission system proposed by the present invention comprises the following steps:

(1) Install the test tooth plate on the rotating part of the power transmission system of the vehicle under test, the test tooth plate and the rotating part are fixed coaxially, and a speed sensor is fixed on the car body or the casing of the rotating part, and the speed sensor is in the test position. On the side of the gear plate, when the vehicle under test accelerates, the rotation signal of the rotating part is collected;

(2) Assuming that the i-th peak value of the rotation signal s(t) of the rotating member appears at the time t _peak (i), then the time period T during which the i-th tooth on the tooth plate corresponding to the i-th peak value sweeps across the speed sensor is tested (i) is:

T(i)＝t _peak (i+1)-t _peak (i)

According to the time period T(i) of the i-th tooth, the time period of the i+1th tooth is calculated as T(i+1), the value of T((i+1)

0＜α＜1，0＜β＜1，在上述取值范围内检索旋转信号的峰值点，得到第i+1个齿的时间周期T(i+1)，依次递推得到测试齿盘上所有齿的时间周期；The range is: αT(i)<T(i+1)<(α+β)T(i), where α and β are periodic coefficients, and α and β satisfy:

0<α<1, 0<β<1, search the peak point of the rotation signal within the above value range, get the time period T(i+1) of the i+1th tooth, and then recursively get the the time period of all teeth;

According to the above time period of all teeth, the instantaneous speed of each tooth is obtained as:

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}$

According to the instantaneous rotational speed of all the teeth above, the average rotational speed of the rotating part is obtained as:

$\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; Z</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>$

Where Z is the number of teeth of the test chainring;

(3) According to the average rotational speed of the above-mentioned rotating parts, the center frequency f _c (t _i ) of the band-pass filter used to filter the instantaneous rotational speed is obtained as:

According to the center frequency of the above-mentioned band-pass filter, the time-discrete form of the windowed impulse response function of the band-pass filter is obtained as:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; rf</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, r is the bandwidth of the bandpass filter, r=β, T _d is the group delay, T _d =N/2F _s , F _s is the sampling frequency of the rotation signal of the rotating part, w _β [t _k ] is the raised cosine window function, [t _k ] is the sampling time series, [t _k ]=k/F _s , (k=0, 1,..., N-1), N is the length of the filter function, N=K/60, K is the the length of the filtered signal;

(4) Linearly interpolate the above-mentioned instantaneous speed n(t _i ) according to the above-mentioned sampling time series [t _k ] to obtain the time-discrete form n[t _k ] of the instantaneous speed, and use the above-mentioned windowed impulse response function h _β [t _k ] to filter the time-discrete form n[t _k ] of the instantaneous speed, and obtain the filtered instantaneous speed of the rotating part as:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>$

The rotation signal collected by the car under test during the entire acceleration process is divided into segments according to the data length of each rotation of the test toothed disc, and steps (2), (3) and (4) are repeated to filter each segment of the signal to obtain the measured Measure the instantaneous speed n _s-all [t _k ] of the rotating parts during the whole acceleration process of the vehicle;

(5) Transform the instantaneous rotational speed _{n s-all} [t _k ] of the rotating parts of the vehicle under test during the entire acceleration process into the frequency domain instantaneous rotational speed n _s (t _p , f) through short-time Fourier transform, where t _p is the moment when the short-time Fourier transform is performed, and the value range of t _p is t _start ≤ t _p ≤ t _end , t _start is the starting moment of the acceleration of the measured vehicle, and t _end is the end of the acceleration of the measured vehicle time, f is the frequency of the instantaneous speed in the frequency domain;

According to the average rotational speed v(t _i ) of the above-mentioned rotating parts, the order frequency of each order of rotating parts is obtained as:

f _m (t _i )=m·v(t _i )

Among them, m is the order;

According to the rotational speed order frequency f _m (t _i ) of each order of the rotating part calculated above, the frequency-domain instantaneous rotational speed n _s (t _p , f) is converted into the order instantaneous rotational speed n _sm [f _m (t _p )] , where f _m (t _p ) is the speed order frequency of the mth order instantaneous speed at time t _p ;

Retrieve the m-th order instantaneous speed n _sm [f _m (t _p )] of the measured vehicle during the entire acceleration process, and obtain the maximum value max{n _sm [f _m (t p )] of this order instantaneous speed _p )]}, the speed order frequency f _m-max (t _p-max ), that is, the order frequency of the torsional vibration signal of the mth order of the rotating part is:

f _m =f _m-max (t _p-max )

Among them, t _p-max is the moment when the maximum value of the instantaneous rotational speed of the mth order of the rotating member appears.

The on-line detection method of the torsional vibration signal of the automobile power transmission system proposed by the present invention collects the rotation signals of each test tooth disk under the accelerated driving condition of the vehicle under test by installing a test tooth disk and a speed sensor on the rotating parts of the power transmission system , calculate the rotational speed of the power transmission system, and then filter it, perform time-frequency analysis on the filtered rotational speed, and calculate the torsional vibration frequency of the system.

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Fig. 1, it is a schematic structural diagram of a test system using the method of the present invention. The power transmission system of a car is composed of engine, clutch, transmission, universal joint, transmission shaft, final reducer, axle shaft and wheels, etc. To measure its torsional vibration, it is necessary to measure the speed of the corresponding position, such as engine speed, transmission speed and The speed of the transmission shaft, etc. is measured. Install the test toothed plate on the corresponding rotating part, the test toothed plate is coaxial with the rotating part and fixed with the rotating part, and the speed sensor is installed on the side of the test toothed plate, and the speed sensor is fixed on the car body or the shell of the rotating part. The rotational speed of the rotating part is measured. In Fig. 1, a test toothed disc is installed at the engine output end, the front end of the transmission shaft and the rear end of the transmission shaft, and the structure of the test toothed disc is shown in Fig. 2 . The outer diameter (tooth top) of the tooth disc is R, and its central aperture is r, which is the same as the diameter of the rotating part. It is fixed on the rotating part. Z rectangular teeth are evenly distributed on the test tooth disc along the circumferential direction (recommended Z = 60, that is, a total of 60 Rectangular teeth), the speed sensor is installed on the side of the test tooth disc, the front probe is perpendicular to the test tooth disc, and the distance from the outer diameter of the tooth disc is 1 to 2mm. The sensor is fixedly connected with the transmission and the main reducer housing, and there is no relative displacement between the sensor and the center plane of the test chainring when the vehicle under test is running.

When the car under test is running, the test tooth disc rotates together with the rotation of the rotating parts such as the engine flywheel and the transmission shaft. Each rectangular tooth of the test tooth disc sweeps the sensor probe in turn, and the position of the probe relative to the convex tooth and the groove changes alternately. An approximately periodic sinusoidal signal is generated in the sensor, and its amplitude and frequency are proportional to the rotational speed of the toothed disc, that is, proportional to the rotational speed of the rotating member. The car under test accelerates, and the acquisition system is used to collect the signal output by the sensor during the whole acceleration process, and the rotation signal of the rotating part under test can be obtained.

Due to the influence of body vibration and other interference signals during the driving process of the tested vehicle, the collected instantaneous rotational speed of the tested rotating part will be distorted, and the processing method proposed by the invention should be used to analyze and process the rotation signal.

Taking the transmission shaft rotation signal s(t) measured in the embodiment as an example, the processing method is as follows:

(1) Peak detection and identification speed

The moment corresponding to the i-th peak point of the rotation signal is t _peak (i), then the time period T(i) of the i-th tooth is

T(i)＝t _peak (i+1)-t _peak (i) (1)

After calculating the time period T(i) of the previous tooth, the value range of the time period T(i+1) of the next tooth is αT(i)<T(i+1)<(α+β)T(i) , where α, β are periodic coefficients.

α and β should satisfy

$\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 1,0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Generally, the value of α is recommended to be 0.85, and the value of β is 0.3.

Find the peak point of the rotation signal within the above value range, calculate the time period T(i+1), and recursively calculate the time period of all teeth.

According to the time period of all teeth obtained by peak point detection, the average rotational speed in each tooth shape (6 degrees) is calculated as the instantaneous rotational speed.

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The instantaneous speed is the superposition of two types of speed fluctuations, such as formula (4), n(t _i ) is the instantaneous speed, v(t _i ) is the average speed of the test toothed disc in one rotation, u(t _i ) is the speed fluctuations.

n(t _i )=v(t _i )+u(t _i ) (4)

v(t _i ) is the average rotational speed of the tested toothed disc within one revolution (360 degrees), expressed as the average instantaneous rotational speed of Z tooth profile periods.

$\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; Z</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The rotational speed fluctuation u(t _i ) contains the information of the torsional vibration of the rotating parts, and is the key analysis object for analyzing the torsional vibration.

(2) Construct filter function

In order to reduce the influence of interference noise, the preliminary calculated instantaneous speed is filtered.

Calculate the frequency f _n (t _i ) of the average rotational speed as the center frequency f _c (t _i ) of the band-pass filter for filtering the preliminarily calculated instantaneous rotational speed, as shown in formula (6).

For a 60-tooth test chainring, the average rotational frequency is equal to the rotating member rotational speed.

The center frequency of the band-pass filter changes once per working cycle with the rotating speed, and the length K of the signal to be filtered is set as the signal length within one rotation of the test toothed disc. The bandwidth r of the bandpass filter covers the frequency fluctuation of the signal to be filtered, which is the previous β value. Calculate the band-pass upper and lower limit frequencies f _H (t _i ) and f _L (t _i ) of the filter according to the center frequency and bandwidth ratio of the band-pass filter, as shown in formula (7).

f _H (t _i )=(1+r)f _c (t _i )

f _L (t _i )=(1-r)f _c (t _i ) (7)

r=β

Construct the frequency domain transfer function H(f) of the digital filter,

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}\mathrm{<span\; class="notranslate">\; f</span>}}& \mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\\ {\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span>}& \mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\\ \mathrm{<span\; class="notranslate">\; 0</span>}& \mathrm{<span\; class="notranslate">\; else</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Among them, T _d is the group delay, that is, the time delay of the filter output relative to the input; F _s is the sampling frequency of the rotation signal. Compute the shock response function h(t).

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

The impulse response function is discretized according to the sampling time series, and the discretized impulse response function is shown in formula (10).

h[t _k ]=4rf _c ·sinc[2rf _c (t _k -T _d )]·cos[2πf _c (t _k -T _d )](10)

[t _k ]=kΔt=k/F _s

Among them, h[t _k ] is the time-discrete form of the shock response function h(t), [t _k ] is the sampling time series, [t _k ]=k/F _s , (k=0,1,…,N- 1), N is the length of the filter function, N=K/60, that is, the length of the signal within one tooth shape of the test tooth disc rotation.

Add a raised cosine window to h[t _k ], and the shock response function h _β [t _k ] after windowing is shown in formula (11).

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

Wherein, w _β [t _k ] is a raised cosine window function, and the group delay T _d is T _d =N/2F _s .

(3) Filter processing of instantaneous speed

Linearly interpolate the instantaneous speed n(t _i ) obtained from the previous preliminary calculation according to the sampling time series [t _k ], and obtain the time-discrete form of the preliminary instantaneous speed n[t _k ] after discretization

Use the discretized windowed impulse response function h _β [t _k ] to filter the time-discrete form of the preliminary instantaneous speed, as shown in formula (12).

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

Among them, n _s [t _k ] is the instantaneous rotational speed after filtering, and K is the length of the signal to be filtered.

Divide the instantaneous rotational speed of the power train during the entire acceleration process by the data length of one revolution of the test gear plate, and filter each segment of the signal according to the above process to obtain the instantaneous rotational speed of the power train during the entire acceleration process n _s-all [t _k ].

(4) Calculation of torsional vibration frequency

The instantaneous speed n _s-all [t _k ] of the rotating parts of the vehicle under test during the whole acceleration process is transformed into the frequency domain instantaneous speed n _s (t _p , f) through short-time Fourier transform, where t _p is The time sequence of short-time Fourier transform, its value range is t _start ≤ t _p ≤ t _end , t _start is the starting moment of the measured car acceleration, t _end is the end moment of the measured car acceleration, f for the frequency.

Calculation of the order frequency of each order of the rotational speed of the rotating member is shown in formula (13).

f _m (t _i )=m·v(t _i ) (13)

According to the rotational speed order frequency f _m (t _i ) of each order of the rotating part calculated above, the frequency-domain instantaneous rotational speed n _s (t _p , f) is converted into the order instantaneous rotational speed n _sm [f _m (t _p )] , where f _m (t _p ) is the speed order frequency of the mth order instantaneous speed at time t _p .

Therefore, the torsional vibration frequency of each order is the extreme frequency of the instantaneous speed of each order, and the instantaneous speed n _sm [f _m (t _p )] of the m-th order in the whole acceleration process of the measured vehicle is retrieved to obtain the The order frequency f _m-max (t p _-max ) of the rotational speed when the instantaneous rotational speed has a maximum value max{n _sm [f _m (t _p )]}, then the torsional vibration order of the mth order of the rotating part The secondary frequency is:

f _m =f _m-max (t _p-max ) (14)

Among them, t _p-max is the moment when the maximum value of the instantaneous rotational speed of the mth order of the rotating member appears.

Claims (1)

1. an on-line detection method of torsional vibration signal of an automobile power transmission system, characterized in that the method may further comprise the steps: (1) Install the test tooth plate on the rotating part of the power transmission system of the vehicle under test, the test tooth plate and the rotating part are fixed coaxially, a speed sensor is fixed on the car body or the casing of the rotating part, and the speed sensor is in the test On the side of the gear plate, when the vehicle under test accelerates, the rotation signal of the rotating part is collected; (2) Assuming that the i-th peak value of the rotation signal s(t) of the rotating member appears at the time t _peak (i), then the time period T during which the i-th tooth on the tooth plate corresponding to the i-th peak value sweeps across the speed sensor is tested (i) is: T(i)＝t _peak (i+1)-t _peak (i) According to the time period T(i) of the i-th tooth, the time period of the i+1th tooth is calculated as T(i+1), and the value range of T(i+1) is: αT(i)<T( i+1)<(α+β)T(i), where α and β are periodic coefficients, and α and β satisfy:

0<α<1, 0<β<1, search the peak point of the rotation signal within the above value range, get the time period T(i+1) of the i+1th tooth, and then recursively get the the time period of all teeth; According to the above time period of all teeth, the instantaneous speed of each tooth is obtained as: $\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; )</span>}$ According to the instantaneous rotational speed of all the above teeth, the average rotational speed of the rotating part is obtained as: $\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; Z</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>$ Where Z is the number of teeth of the test chainring; (3) According to the average rotational speed of the above-mentioned rotating parts, the center frequency f _c (t _i ) of the band-pass filter used to filter the instantaneous rotational speed is obtained as:

According to the center frequency of the above-mentioned band-pass filter, the time-discrete form of the windowed impulse response function of the band-pass filter is obtained as: ${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&beta;</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; r</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ Among them, r is the bandwidth of the bandpass filter, r=β, T _d is the group delay, T _d =N/2F _s , F _s is the sampling frequency of the rotation signal of the rotating part, w _β [t _k ] is the raised cosine window function, [t _k ] is the sampling time series, [t _k ]=k/F _s , (k=0, 1,..., N-1), N is the length of the filter function, N=K/60, K is the the length of the filtered signal; (4) Linearly interpolate the above-mentioned instantaneous speed n(t _i ) according to the above-mentioned sampling time series [t _k ] to obtain the time-discrete form n[t _k ] of the instantaneous speed, and use the above-mentioned windowed impulse response function h _β [t _k ] to filter the time-discrete form n[t _k ] of the instantaneous speed, and obtain the filtered instantaneous speed of the rotating part as: ${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>$ The rotation signal collected by the car under test during the entire acceleration process is divided into segments according to the data length of each rotation of the test toothed disc, and steps (2), (3) and (4) are repeated to filter each segment of the signal to obtain the measured Measure the instantaneous speed n _s-all [t _k ] of the rotating parts during the whole acceleration process of the vehicle; (5) Transform the instantaneous rotational speed _{n s-all} [t _k ] of the rotating parts of the vehicle under test during the entire acceleration process into the frequency domain instantaneous rotational speed n _s (t _p , f) through short-time Fourier transform, where t _p is the moment when the short-time Fourier transform is performed, and the value range of t _p is t _start ≤ t _p ≤ t _end , t _start is the starting moment of the acceleration of the measured vehicle, and t _end is the end of the acceleration of the measured vehicle time, f is the frequency of the instantaneous speed in the frequency domain; According to the average rotational speed v(t _i ) of the above-mentioned rotating parts, the order frequency of each order of rotating parts is obtained as: f _m (t _i )=m·v(t _i ) Among them, m is the order; According to the rotational speed order frequency f _m (t _i ) of each order of the rotating part calculated above, the frequency-domain instantaneous rotational speed n _s (t _p , f) is converted into the order instantaneous rotational speed n _sm [t _m (t _p )] , where f _m (t _p ) is the speed order frequency of the mth order instantaneous speed at time t _p ; Retrieve the m-th order instantaneous speed n _sm [f _m (t _p )] of the measured vehicle during the entire acceleration process, and obtain the maximum value max{n _sm [f _m (t p )] of this order instantaneous speed _p )]}, the speed order frequency f _m-max (t _p-max ), that is, the order frequency of the torsional vibration signal of the mth order of the rotating part is: f _m =f _m-max (t _p-max ) Among them, t _p-max is the moment when the maximum value of the instantaneous rotational speed of the mth order of the rotating member appears.

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