CN101871846A - Online detection method for torsion vibration signal of automotive power transmission system - Google Patents

Abstract

The invention relates to an online detection method for a torsion vibration signal of an automotive power transmission system, and belongs to the field of automobile noise and vibration control. In the method, torsion vibration test and analysis are performed on a power transmission system of a running front-engine rear-drive independent suspension type vehicle. A testing disc and a rotating speed sensor are arranged at the tested position of the power transmission system and are used for measuring rotating signals of the power transmission system, performing self-adaptive filtering on the signals, performing time-frequency analysis on the filtered signals, and calculating the torsion vibration frequency of the system. The method is used for performing torsion test and analysis on the acceleration running working conditions of an actual vehicle, particularly the running front-engine rear-drive independent suspension type vehicle without a torsion vibration test rack. The testing disc and the rotating speed sensor are arranged at the tested position of the power transmission system and are used for measuring the rotating signals of the power transmission system, calculating the instantaneous rotating speed through the peak value detection, filtering, and calculating the torsion vibration frequency of the system through the time-frequency analysis of the filtered signals.

Description

Online detection method for torsional vibration signal of automobile power transmission system

Technical Field

The invention relates to an online detection method for a torsional vibration signal of an automobile power transmission system, in particular to a method for performing torsional vibration test and analysis on the power transmission system of a front-mounted and rear-mounted independent suspension type vehicle, and belongs to the field of automobile noise and vibration control.

Background

The vehicle driveline is a complex, multiple degree of freedom vibration system that is an important source of excitation for vehicle vibration and noise, where torsional vibration is one of the fundamental vibration modes of the driveline. For a vehicle with a front engine, a rear wheel drive and an independent suspension structure, the power of the engine is transmitted to the rear part of the vehicle through a transmission shaft, and the probability of generating torsional vibration in the transmission process is increased due to the long power transmission distance; the main speed reducer of the vehicle adopting the rear independent suspension structure is directly connected to the vehicle body, so that the torsional vibration of a power transmission system is directly transmitted to the vehicle body of the vehicle, the smoothness of the vehicle is seriously influenced, and larger noise in the vehicle is generated.

Aiming at the problem of vibration noise caused by the torsion of the power transmission system, the torsional vibration characteristics of the crankshaft of the engine and the rotating shaft of the transmission system can be tested and analyzed through a torsional vibration experiment of the power transmission system. And analyzing the torsional resonance of the power transmission system and the main position and frequency characteristics of the system in the torsional resonance according to the obtained excitation and response characteristics of the torsional vibration of the system.

The torsional vibration measurement of a rotating shaft system can be divided into a contact type and a non-contact type, the torsional vibration test of a vehicle power transmission system aims at analyzing the main position and frequency characteristics of torsional resonance of the system, the stress or deformation of the shaft system is not related, a non-contact type torsional vibration test method is preferably adopted, and the torsional vibration analysis of the vehicle power transmission system is usually carried out by adopting a simulation and experiment bench method in the test analysis (Guilei, the research on the dynamic vibration characteristics of a gear transmission system of an automobile gearbox, vibration and impact, 2010; Mingqie, the research on the torsional vibration of the shaft system of a certain locomotive diesel generating set based on a three-dimensional finite element entity, diesel engine, 2008). For the rotating signal of the power transmission system under the acceleration working condition, the frequency fluctuation range is wide, the expected effect is difficult to achieve by adopting the traditional testing and analyzing method, the distortion principle of the actually-measured torsion signal is complicated, most of the actually-measured torsion signal is accompanied by randomness, and accurate identification is difficult. Therefore, how to accurately and effectively measure and analyze the torsional vibration condition of the power transmission system under the actual vehicle acceleration condition is the key for improving the vehicle vibration and noise.

Disclosure of Invention

The invention aims to provide an online detection method for a torsional vibration signal of an automobile power transmission system, which does not need a bench test of the torsional vibration system. The torsional vibration test and analysis are directly carried out on a power transmission system of an actually running vehicle, particularly a front-engine rear-drive independent suspension type vehicle. And mounting a testing fluted disc and a rotating speed sensor at the measured position of the power transmission system, measuring a rotating signal of the power transmission system, carrying out self-adaptive filtering on the rotating signal, carrying out time-frequency analysis on the filtered signal, and calculating the torsional vibration frequency of the system.

The invention provides an online detection method for a torsional vibration signal of an automobile power transmission system, which comprises the following steps:

(1) the method comprises the steps that a testing fluted disc is arranged on a rotating piece of a tested automobile power transmission system, the testing fluted disc and the rotating piece are coaxially fixed, a rotating speed sensor is fixed on an automobile body or a shell of the rotating piece and is positioned on the side face of the testing fluted disc, and when the tested automobile runs in an accelerated mode, rotating signals of the rotating piece are collected;

(2) set at time t_peak(i) When the ith peak value appears in the rotation signal s (t) of the rotating member, the time period t (i) when the ith tooth corresponding to the ith peak value on the test fluted disc sweeps over the rotation speed sensor is as follows:

T(i)＝t_peak(i+1)-t_peak(i)

according to the time period T (i) of the ith tooth, calculating the time period of the (i +1) th tooth to be T (i +1), wherein the value of T (i +1)

The range is as follows: α T (i) < T (i +1) < (α + β) T (i), wherein α, β are periodic coefficients, α and β satisfy:

alpha is more than 0 and less than 1, beta is more than 0 and less than 1, the peak point of the rotation signal is searched in the value range to obtain the time period T (i +1) of the (i +1) th tooth, and the time periods of all the teeth on the testing fluted disc are obtained by successive recursion;

according to the time periods of all the teeth, the instantaneous rotating speed of each tooth is obtained as follows:

$n\left(t_i\right)=\frac{1}{T\left(i\right)}$

and obtaining the average rotating speed of the rotating member according to the instantaneous rotating speeds of all the teeth as follows:

<math><mrow><mi>v</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>=</mo><mfrac><mn>1</mn><mi>Z</mi></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>Z</mi></munderover><mi>n</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow></mrow></math>

wherein Z is the number of teeth of the test cog;

(3) obtaining the center frequency f of the band-pass filter for filtering the instantaneous speed according to the average speed of the rotating member_c(t_i) Comprises the following steps:

according to the center frequency of the band-pass filter, the time discrete form of the windowing impact response function of the band-pass filter is obtained as follows:

<math><mrow><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><mrow><mn>1</mn><mo>+</mo><mi>&beta;</mi></mrow></mfrac><msub><mi>w</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>{</mo><mn>4</mn><mi>r</mi><msub><mi>f</mi><mi>c</mi></msub><mo>&CenterDot;</mo><mi>sin</mi><mi>c</mi><mo>[</mo><mn>2</mn><mi>r</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>&CenterDot;</mo><mi>cos</mi><mo>[</mo><mn>2</mn><mi>&pi;</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>}</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>0,1</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow></mrow></math>

where r is the bandwidth of the bandpass filter, and r is β, T_dFor group delay, T_d＝N/2F_s，F_sFor sampling frequency, w, of rotary signals of rotary members_β[t_k]To raise the cosine window function, [ t ]_k]For sampling time series, [ t ]_k]＝k/F_s(K-0, 1, …, N-1), N being the filter function length, N-K/60, K being the length of the signal to be filtered;

(4) the above-mentioned instantaneous rotational speed n (t)_i) According to the above-mentioned sampling time sequence t_k]Linear interpolation is carried out to obtain the time discrete form n [ t ] of the instantaneous rotating speed_k]Using the windowed impulse response function h_β[t_k]Time discrete form n [ t ] of instantaneous speed_k]Filtering is carried out, and the obtained instantaneous rotating speed of the filtered rotating part is as follows:

<math><mrow><msub><mi>n</mi><mi>s</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><msub><mi>F</mi><mi>s</mi></msub></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>n</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>N</mi><mo>-</mo><mn>1</mn></mrow></munderover><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mi>n</mi><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>1,2</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>K</mi><mo>)</mo></mrow></mrow></math>

segmenting the rotation signal acquired by the tested automobile in the whole acceleration process according to the data length of each rotation circle of the test fluted disc, repeating the steps (2), (3) and (4), and filtering each segment of signal to obtain the instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process_s-all[t_k]；

(5) The instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process_s-all[t_k]Converting into frequency domain instantaneous speed n by short-time Fourier transform_s(t_pF) where t is_pTime of short-time Fourier transform, t_pHas a value range of t_start≤t_p≤t_end，t_startIs the starting time, t, of the acceleration of the vehicle under test_endThe end time of the acceleration of the detected automobile, and f is the frequency of the frequency domain instantaneous rotating speed;

according to the average rotating speed v (t) of the rotating member_i) And obtaining the rotating speed order frequency of each order of the rotating part as follows:

f_m(t_i)＝m·v(t_i)

wherein m is the order;

the rotating speed order frequency f of each order of the rotating part is obtained according to the calculation_m(t_i) The frequency domain instantaneous speed n_s(t_pF) conversion into an order instantaneous speed n_s-m[f_m(f_p)]Wherein f is_m(t_p) The order of the m-th order is the instantaneous speed at t_pThe rotational speed order frequency of the moment;

for the mth order instantaneous speed n in the whole acceleration process of the tested automobile_s-m[f_m(t_p)]Searching to obtain maximum value max n of the order instantaneous rotation speed_s-m[f_m(t_p)]The order frequency f of the rotation speed at_m-max(t_p-max) That is, the order frequency of the mth order torsional vibration signal of the rotating member is:

f_m＝f_m-max(t_p-max)

wherein, t_p-maxThe moment when the maximum value occurs in the mth order instantaneous rotational speed of the rotor.

The invention provides an online detection method for a torsional vibration signal of an automobile power transmission system, which has the advantages that:

1. the online detection method does not need to establish a torsional vibration test bench, does not need to arrange the power transmission system on the bench according to the actual vehicle structure, directly uses the actual vehicle power transmission system as a test object, and simplifies the test steps and equipment;

2. the online detection method can test the torsional vibration condition of the power transmission system of the tested vehicle under the actual acceleration running condition;

3. the online detection method can reduce the influence of rotation speed distortion caused by the vibration of the vehicle, improve the analysis precision and accurately calculate the torsional vibration frequency of the power transmission system.

Drawings

FIG. 1 is a schematic diagram of a test system used in an on-line detection method according to the present invention.

FIG. 2 is a block diagram of a test chain ring.

Fig. 3 is a schematic diagram of peak detection.

Detailed Description

The invention provides an online detection method for a torsional vibration signal of an automobile power transmission system, which comprises the following steps:

(1) the method comprises the steps that a testing fluted disc is arranged on a rotating piece of a tested automobile power transmission system, the testing fluted disc and the rotating piece are coaxially fixed, a rotating speed sensor is fixed on an automobile body or a shell of the rotating piece and is positioned on the side face of the testing fluted disc, and when the tested automobile runs in an accelerated mode, rotating signals of the rotating piece are collected;

(2) set at time t_peak(i) When the ith peak value appears in the rotation signal s (t) of the rotating member, the time period t (i) when the ith tooth corresponding to the ith peak value on the test fluted disc sweeps over the rotation speed sensor is as follows:

T(i)＝t_peak(i+1)-t_peak(i)

according to the time period T (i) of the ith tooth, the time period of the (i +1) th tooth is calculated to be T (i +1), and the value of T ((i +1) is calculated

The range is as follows: α T (i) < T (i +1) < (α + β) T (i), wherein α, β are periodic coefficients, α and β satisfy:

alpha is more than 0 and less than 1, beta is more than 0 and less than 1, the peak point of the rotation signal is searched in the value range to obtain the time period T (i +1) of the (i +1) th tooth, and the time periods of all the teeth on the testing fluted disc are obtained by successive recursion;

according to the time periods of all the teeth, the instantaneous rotating speed of each tooth is obtained as follows:

$n\left(t_i\right)=\frac{1}{T\left(i\right)}$

and obtaining the average rotating speed of the rotating member according to the instantaneous rotating speeds of all the teeth as follows:

<math><mrow><mi>v</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>=</mo><mfrac><mn>1</mn><mi>Z</mi></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>Z</mi></munderover><mi>n</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow></mrow></math>

wherein Z is the number of teeth of the test cog;

(3) obtaining the center frequency f of the band-pass filter for filtering the instantaneous speed according to the average speed of the rotating member_c(t_i) Comprises the following steps:

according to the center frequency of the band-pass filter, the time discrete form of the windowing impact response function of the band-pass filter is obtained as follows:

<math><mrow><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><mrow><mn>1</mn><mo>+</mo><mi>&beta;</mi></mrow></mfrac><msub><mi>w</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>{</mo><mn>4</mn><mi>r</mi><msub><mi>f</mi><mi>c</mi></msub><mo>&CenterDot;</mo><mi>sin</mi><mi>c</mi><mo>[</mo><mn>2</mn><msub><mi>rf</mi><mi>c</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>&CenterDot;</mo><mi>cos</mi><mo>[</mo><mn>2</mn><mi>&pi;</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>}</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>0,1</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow></mrow></math>

where r is the bandwidth of the bandpass filter, and r is β, T_dFor group delay, T_d＝N/2F_s，F_sFor sampling frequency, w, of rotary signals of rotary members_β[t_k]To raise the cosine window function, [ t ]_k]For sampling time series, [ t ]_k]＝k/F_s(K-0, 1, …, N-1), N being the filter function length, N-K/60, K being the length of the signal to be filtered;

(4) the above-mentioned instantaneous rotational speed n (t)_i) According to the above-mentioned sampling time sequence t_k]Linear interpolation is carried out to obtain the time discrete form n [ t ] of the instantaneous rotating speed_k]Using the windowed impulse response function h_β[t_k]Time discrete form n [ t ] of instantaneous speed_k]Filtering is carried out, and the obtained instantaneous rotating speed of the filtered rotating part is as follows:

<math><mrow><msub><mi>n</mi><mi>s</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><msub><mi>F</mi><mi>s</mi></msub></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>n</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>N</mi><mo>-</mo><mn>1</mn></mrow></munderover><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mi>n</mi><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>1,2</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>K</mi><mo>)</mo></mrow></mrow></math>

the rotation signal collected by the tested automobile in the whole acceleration process rotates one circle according to the test fluted discThe data length is segmented, the steps (2), (3) and (4) are repeated, each segment of signal is filtered, and the instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process is obtained_s-all[t_k]；

(5) The instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process_s-all[t_k]Converting into frequency domain instantaneous speed n by short-time Fourier transform_s(t_pF) where t is_pTime of short-time Fourier transform, t_pHas a value range of t_start≤t_p≤t_end，t_startIs the starting time, t, of the acceleration of the vehicle under test_endThe end time of the acceleration of the detected automobile, and f is the frequency of the frequency domain instantaneous rotating speed;

according to the average rotating speed v (t) of the rotating member_i) And obtaining the rotating speed order frequency of each order of the rotating part as follows:

f_m(t_i)＝m·v(t_i)

wherein m is the order;

the rotating speed order frequency f of each order of the rotating part is obtained according to the calculation_m(t_i) The frequency domain instantaneous speed n_s(t_pF) conversion into an order instantaneous speed n_s-m[f_m(t_p)]Wherein f is_m(t_p) The order of the m-th order is the instantaneous speed at t_pThe rotational speed order frequency of the moment;

for the mth order instantaneous speed n in the whole acceleration process of the tested automobile_s-m[f_m(t_p)]Searching to obtain maximum value max n of the order instantaneous rotation speed_s-m[f_m(t_p)]The order frequency f of the rotation speed at_m-max(t_p-max) That is, the order frequency of the mth order torsional vibration signal of the rotating member is:

f_m＝f_m-max(t_p-max)

wherein,t_p-maxthe moment when the maximum value occurs in the mth order instantaneous rotational speed of the rotor.

The invention provides an on-line detection method for torsional vibration signals of an automobile power transmission system, which is characterized in that a test fluted disc and a rotating speed sensor are arranged on a rotating part of the power transmission system, the rotating signals of the test fluted disc of a tested automobile under an acceleration running working condition are collected, the rotating speed of the power transmission system is calculated and then filtered, the filtered rotating speed is subjected to time-frequency analysis, and the torsional vibration frequency of the system is calculated.

The invention is described in detail below with reference to the figures and examples.

FIG. 1 is a schematic diagram of a test system using the method of the present invention. The power transmission system of the automobile comprises an engine, a clutch, a transmission, a universal joint, a transmission shaft, a main reducer, a half shaft, wheels and the like, and the rotating speeds of corresponding positions, such as the rotating speed of the engine, the rotating speed of the transmission shaft and the like, need to be measured when the torsional vibration condition of the automobile is measured. The testing fluted disc is installed on the corresponding rotating piece, the testing fluted disc is coaxial with the rotating piece and is fixed with the rotating piece, a rotating speed sensor is installed on the side face of the testing fluted disc, and the rotating speed sensor is fixed on a car body or a shell of the rotating piece to measure the rotating speed of the rotating piece. In fig. 1, the test fluted discs are installed at the output end of the engine, the front end of the transmission shaft and the rear end of the transmission shaft, and the structure of the test fluted disc is shown in fig. 2. Fluted disc external diameter (top) is R, and its central aperture is R and rotates the diameter the same, concreties on rotating the piece, along the circumference equipartition Z rectangle tooth (recommend Z60, 60 rectangle teeth altogether promptly) on the test fluted disc, at the side-mounting rotational speed sensor of test fluted disc, its front end probe perpendicular to test fluted disc, is 1 to 2mm apart from the fluted disc external diameter. The sensor is fixedly connected with the speed changer and the main speed reducer shell, and no relative displacement exists between the sensor and the central plane of the testing fluted disc when the tested automobile runs.

When the automobile to be tested runs, the testing fluted disc rotates along with the rotation of the rotating parts such as the engine flywheel, the transmission shaft and the like, all the rectangular teeth of the testing fluted disc sweep the probe of the sensor in turn, the positions of the probe relative to the convex teeth and the grooves are changed alternately, an approximately periodic sinusoidal signal is generated in the sensor, and the amplitude and the frequency of the approximately periodic sinusoidal signal are in direct proportion to the rotating speed of the fluted disc, namely the rotating speed of the rotating parts. The detected automobile runs in an accelerated mode, the acquisition system is used for acquiring signals output by the sensor in the whole accelerating process, and then the rotating signals of the detected rotating piece can be obtained.

Due to the influence of the vibration of the vehicle body and other interference signals in the running process of the tested vehicle, the acquired instantaneous rotating speed of the tested rotating part generates distortion, and the rotating signal is analyzed and processed by using the processing method provided by the invention.

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

(1) peak detection identification rotating speed

The time corresponding to the ith peak point of the rotation signal is t_peak(i) The time period T (i) of the ith tooth is

T(i)＝t_peak(i+1)-t_peak(i) (1)

After the time period T (i) of the previous tooth is calculated, the value of the time period T (i +1) of the next tooth ranges from alpha T (i) < T (i +1) < (alpha + beta) T (i), wherein alpha and beta are period coefficients.

Alpha and beta should satisfy

<math><mrow><mi>&alpha;</mi><mo>+</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mi>&beta;</mi><mo>=</mo><mn>1,0</mn><mo>&lt;</mo><mi>&alpha;</mi><mo>&lt;</mo><mn>1,0</mn><mo>&lt;</mo><mi>&beta;</mi><mo>&lt;</mo><mn>1</mn><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></math>

In general, the value of alpha is recommended to be 0.85, and the value of beta is recommended to be 0.3.

And searching a peak point of the rotation signal in the value range, calculating a time period T (i +1), and calculating the time periods of all teeth in a recursion manner.

And calculating the average rotating speed in each tooth form (6 degrees) according to the time period of all the teeth detected by the peak point as the instantaneous rotating speed.

$n\left(t_i\right)=\frac{1}{T\left(i\right)}---\left(3\right)$

The instantaneous speed is the superposition of two types of speed fluctuation, as shown in formula (4), n (t)_i) Is the instantaneous speed of rotation, v (t)_i) To measure the average speed of rotation, u (t), of the toothed disc during one revolution_i) Is the fluctuation of the rotating speed in one rotation.

n(t_i)＝v(t_i)+u(t_i) (4)

v(t_i) Is the average rotational speed of the test toothed disc over one revolution (360 degrees) and is expressed as the average of the instantaneous rotational speeds of the Z tooth periods.

<math><mrow><mi>v</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>=</mo><mfrac><mn>1</mn><mi>Z</mi></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>Z</mi></munderover><mi>n</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>5</mn><mo>)</mo></mrow></mrow></math>

Speed fluctuation u (t)_i) The method includes the torsional vibration information of the rotating member, and is an important analysis for analyzing the torsional vibrationAn object.

(2) Constructing a filter function

And filtering the preliminarily calculated instantaneous rotating speed in order to reduce the influence of interference noise.

Calculating the frequency f of the mean speed_n(t_i) Center frequency f of band-pass filter as filter for preliminary calculated instantaneous speed_c(t_i) As shown in equation (6).

For a 60 tooth test gear disc, the average rotational frequency is equal to the rotational speed of the rotor.

The central frequency of the band-pass filter changes once in each working period along with the rotating speed, and the length K of the signal to be filtered is set to be the length of the signal in one rotation of the testing fluted disc. The bandwidth r of the band-pass filter covers the frequency fluctuations of the signal to be filtered, i.e. the previous value of β. Calculating the upper and lower band-pass limit frequencies f of the filter according to the center frequency and the bandwidth ratio of the band-pass filter_H(t_i) And f_L(t_i) As shown in equation (7).

f_H(t_i)＝(1+r)f_c(t_i)

f_L(t_i)＝(1-r)f_c(t_i) (7)

r＝β

Constructing the frequency domain transfer function h (f) of the digital filter,

<math><mrow><mi>H</mi><mrow><mo>(</mo><mi>f</mi><mo>)</mo></mrow><mo>=</mo><mfenced open='{' close=''><mtable><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;</mi><msub><mi>T</mi><mi>d</mi></msub><mi>f</mi></mrow></msup></mtd><mtd><mi>f</mi><mo>&Element;</mo><mo>[</mo><msub><mi>f</mi><mi>L</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>,</mo><msub><mi>f</mi><mi>H</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>]</mo></mtd></mtr><mtr><mtd><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;</mi><msub><mi>T</mi><mi>d</mi></msub><mrow><mo>(</mo><mi>f</mi><mo>-</mo><msub><mi>F</mi><mi>s</mi></msub><mo>)</mo></mrow></mrow></msup></mtd><mtd><mi>f</mi><mo>&Element;</mo><mo>[</mo><msub><mi>F</mi><mi>s</mi></msub><mo>-</mo><msub><mi>f</mi><mi>H</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>,</mo><msub><mi>F</mi><mi>s</mi></msub><mo>-</mo><msub><mi>f</mi><mi>L</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>]</mo></mtd></mtr><mtr><mtd><mn>0</mn></mtd><mtd><mi>else</mi></mtd></mtr></mtable></mfenced><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>8</mn><mo>)</mo></mrow></mrow></math>

wherein, T_dIs the group delay, i.e., the time delay of the filter output relative to the input; f_sIs the sampling frequency of the rotation signal. The impulse response function h (t) is calculated.

<math><mrow><mi>h</mi><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow><mo>=</mo><mn>2</mn><mi>r</mi><msub><mi>f</mi><mi>c</mi></msub><mo>&CenterDot;</mo><mi>sin</mi><mi>c</mi><mo>[</mo><mn>2</mn><mi>&pi;r</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>&CenterDot;</mo><mo>[</mo><msup><mi>e</mi><mrow><mi>j</mi><mn>2</mn><mi>&pi;</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow></mrow></msup><mo>+</mo><msup><mi>e</mi><mrow><mi>j</mi><mn>2</mn><mi>&pi;</mi><msub><mi>F</mi><mi>s</mi></msub><mi>t</mi></mrow></msup><msup><mi>e</mi><mrow><mo>-</mo><mi>j</mi><mn>2</mn><mi>&pi;</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><mi>t</mi><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow></mrow></msup><mo>]</mo><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>9</mn><mo>)</mo></mrow></mrow></math>

And (3) dispersing the impact response function according to the sampling time sequence, and dispersing the impact response function after discretization, as 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

Wherein, h [ t_k]Is a time discrete form of the impulse response function h (t) [ t_k]For sampling time series, [ t ]_k]＝k/F_sAnd (K is 0, 1, …, N-1), where N is the filter function length and N is K/60, i.e. the length of the signal within one tooth profile of the test tooth disk.

For h [ t ]_k]Raising cosine window, impact response function h after window_β[t_k]As shown in formula (11).

<math><mrow><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><mrow><mn>1</mn><mo>+</mo><mi>&beta;</mi></mrow></mfrac><msub><mi>w</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mi>h</mi><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>0,1</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>11</mn><mo>)</mo></mrow></mrow></math>

Wherein, w_β[t_k]To raise the cosine window function, the group delay T_dIs T_d＝N/2F_s。

(3) Filtering of instantaneous speed

The instantaneous speed n (t) obtained by the preliminary calculation is used_i) In a sampling time sequence t_k]Linear interpolation is carried out, and a time dispersion form n [ t ] of the initial instantaneous rotating speed is obtained after dispersion_k]

Using discretized windowed impulse response function h_β[t_k]The time-discrete form of the preliminary instantaneous rotational speed is filtered as shown in equation (12).

<math><mrow><msub><mi>n</mi><mi>s</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><msub><mi>F</mi><mi>s</mi></msub></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>n</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>N</mi><mo>-</mo><mn>1</mn></mrow></munderover><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mi>n</mi><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>1,2</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>K</mi><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>12</mn><mo>)</mo></mrow></mrow></math>

Wherein n is_s[t_k]Is the instantaneous speed after filtering, and K is the length of the signal to be filtered.

Dividing the instantaneous rotating speed of the power transmission system in the whole acceleration process according to the data length of one circle of rotation of the test fluted disc, and filtering each section of signal according to the process to obtain the whole acceleration processInstantaneous speed n of the intermediate drive train_s-all[t_k]。

(4) Calculating torsional vibration frequency

The instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process_s-all[t_k]Converting into frequency domain instantaneous speed n by short-time Fourier transform_s(t_pF) where t is_pThe time period sequence for short-time Fourier transform has a value range of t_start≤t_p≤t_end，t_startIs the starting time, t, of the acceleration of the vehicle under test_endIs the end time of the acceleration of the detected automobile, and f is the frequency.

The calculation of the rotational speed order frequency of the rotor for each step is shown in equation (13).

f_m(t_i)＝m·v(t_i) (13)

The rotating speed order frequency f of each order of the rotating part is obtained according to the calculation_m(t_i) The frequency domain instantaneous speed n_s(t_pF) conversion into an order instantaneous speed n_s-m[f_m(t_p)]Wherein f is_m(t_p) The order of the m-th order is the instantaneous speed at t_pThe rotational speed order frequency of the moment.

Therefore, the torsional vibration frequency of each order is the extreme frequency of the instantaneous rotating speed of each order, and the m-th order instantaneous rotating speed n of the tested automobile in the whole acceleration process is subjected to_s-m[f_m(t_p)]Searching to obtain maximum value max n of the order instantaneous rotation speed_s-m[f_m(t_p)]The order frequency f of the rotation speed at_m-max(t_p-max) Then, the mth order torsional vibration order frequency of the rotating member is:

f_m＝f_m-max(t_p-max) (14)

wherein, t_p-maxOf order m of the rotary memberThe moment when the order instantaneous speed is maximum.

Claims (1)

1. An online detection method for a torsional vibration signal of an automobile power transmission system is characterized by comprising the following steps:

(1) the method comprises the steps that a testing fluted disc is arranged on a rotating piece of a tested automobile power transmission system, the testing fluted disc and the rotating piece are coaxially fixed, a rotating speed sensor is fixed on an automobile body or a shell of the rotating piece and is positioned on the side face of the testing fluted disc, and when the tested automobile runs in an accelerated mode, rotating signals of the rotating piece are collected;

(2) set at time t_peak(i) The time-rotating member rotates a signal s (t)When the ith peak appears, the time period t (i) of the ith tooth on the test fluted disc, which is scanned by the rotation speed sensor and corresponds to the ith peak, is:

T(i)＝t_peak(i+1)-t_peak(i)

according to the time period T (i) of the ith tooth, calculating the time period of the (i +1) th tooth to be T (i +1), wherein the value range of the T (i +1) is as follows: α T (i) < T (i +1) < (α + β) T (i), wherein α, β are periodic coefficients, α and β satisfy:

alpha is more than 0 and less than 1, beta is more than 0 and less than 1, the peak point of the rotation signal is searched in the value range to obtain the time period T (i +1) of the (i +1) th tooth, and the time periods of all the teeth on the testing fluted disc are obtained by successive recursion;

according to the time periods of all the teeth, the instantaneous rotating speed of each tooth is obtained as follows:

$n\left(t_i\right)=\frac{1}{T\left(i\right)}$

and obtaining the average rotating speed of the rotating member according to the instantaneous rotating speeds of all the teeth as follows:

<math><mrow><mi>v</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow><mo>=</mo><mfrac><mn>1</mn><mi>Z</mi></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>Z</mi></munderover><mi>n</mi><mrow><mo>(</mo><msub><mi>t</mi><mi>i</mi></msub><mo>)</mo></mrow></mrow></math>

wherein Z is the number of teeth of the test cog;

(3) obtaining the center frequency f of the band-pass filter for filtering the instantaneous speed according to the average speed of the rotating member_c(t_i) Comprises the following steps:

according to the center frequency of the band-pass filter, the time discrete form of the windowing impact response function of the band-pass filter is obtained as follows:

<math><mrow><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><mrow><mn>1</mn><mo>+</mo><mi>&beta;</mi></mrow></mfrac><msub><mi>w</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>{</mo><mn>4</mn><mi>r</mi><msub><mi>f</mi><mi>c</mi></msub><mo>&CenterDot;</mo><mi>sin</mi><mi>c</mi><mo>[</mo><mn>2</mn><mi>r</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>&CenterDot;</mo><mi>cos</mi><mo>[</mo><mn>2</mn><mi>&pi;</mi><msub><mi>f</mi><mi>c</mi></msub><mrow><mo>(</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>T</mi><mi>d</mi></msub><mo>)</mo></mrow><mo>]</mo><mo>}</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>0,1</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>N</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow></mrow></math>

where r is the bandwidth of the bandpass filter, and r is β, T_dFor group delay, T_d＝N/2F_s，F_sFor sampling frequency, w, of rotary signals of rotary members_β[t_k]To raise the cosine window function, [ t ]_k]For sampling time series, [ t ]_k]＝k/F_s(K-0, 1, …, N-1), N being the filter function length, N-K/60, K being the length of the signal to be filtered;

(4) the above-mentioned instantaneous rotational speed n (t)_i) According to the above-mentioned sampling time sequence t_k]Linear interpolation is carried out to obtain the time discrete form n [ t ] of the instantaneous rotating speed_k]Using the windowed impulse response functionh_β[t_k]Time discrete form n [ t ] of instantaneous speed_k]Filtering is carried out, and the obtained instantaneous rotating speed of the filtered rotating part is as follows:

<math><mrow><msub><mi>n</mi><mi>s</mi></msub><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>]</mo><mo>=</mo><mfrac><mn>1</mn><msub><mi>F</mi><mi>s</mi></msub></mfrac><munderover><mi>&Sigma;</mi><mrow><mi>n</mi><mo>=</mo><mn>0</mn></mrow><mrow><mi>N</mi><mo>-</mo><mn>1</mn></mrow></munderover><msub><mi>h</mi><mi>&beta;</mi></msub><mo>[</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mi>n</mi><mo>[</mo><msub><mi>t</mi><mi>k</mi></msub><mo>-</mo><msub><mi>t</mi><mi>n</mi></msub><mo>]</mo><mo>,</mo><mrow><mo>(</mo><mi>k</mi><mo>=</mo><mn>1,2</mn><mo>,</mo><mo>.</mo><mo>.</mo><mo>.</mo><mo>,</mo><mi>K</mi><mo>)</mo></mrow></mrow></math>

segmenting the rotation signal acquired by the tested automobile in the whole acceleration process according to the data length of each rotation circle of the test fluted disc, repeating the steps (2), (3) and (4), and filtering each segment of signal to obtain the instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process_s-all[t_k]；

(5) The instantaneous rotating speed n of the rotating member of the tested automobile in the whole acceleration process_s-all[t_k]Converting into frequency domain instantaneous speed n by short-time Fourier transform_s(t_pF) where t is_pTime of short-time Fourier transform, t_pHas a value range of t_start≤t_p≤t_end，t_startIs the starting time, t, of the acceleration of the vehicle under test_endThe end time of the acceleration of the detected automobile, and f is the frequency of the frequency domain instantaneous rotating speed;

according to the average rotating speed v (t) of the rotating member_i) And obtaining the rotating speed order frequency of each order of the rotating part as follows:

f_m(t_i)＝m·v(t_i)

wherein m is the order;

according toThe calculated rotation speed order frequency f of each step of the rotating part_m(t_i) The frequency domain instantaneous speed n_s(t_pF) conversion into an order instantaneous speed n_s-m[t_m(t_p)]Wherein f is_m(t_p) The order of the m-th order is the instantaneous speed at t_pThe rotational speed order frequency of the moment;

for the mth order instantaneous speed n in the whole acceleration process of the tested automobile_s-m[f_m(t_p)]Searching to obtain maximum value max n of the order instantaneous rotation speed_s-m[f_m(t_p)]The order frequency f of the rotation speed at_m-max(t_p-max) That is, the order frequency of the mth order torsional vibration signal of the rotating member is:

f_m＝f_m-max(t_p-max)

wherein, t_p-maxThe moment when the maximum value occurs in the mth order instantaneous rotational speed of the rotor.

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