CN114370998B - Automatic diagnosis method and system for gear fault of gear box - Google Patents
Automatic diagnosis method and system for gear fault of gear box Download PDFInfo
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Abstract
The invention discloses a method and a system for automatically diagnosing gear faults of a gear box, which relate to the field of mechanical equipment state monitoring, and the method comprises the following steps: acquiring a vibration acceleration signal of a gear shaft in a target gear box and the meshing frequency of gears on the gear shaft; determining a speed spectrum and an envelope spectrum of the gear shaft according to the vibration acceleration signal; determining a modulation frequency identifier according to the maximum energy frequency component in the meshing frequency and envelope spectrum; calculating an engagement frequency energy ratio, a side frequency energy ratio and a side frequency energy ratio according to the frequency component with the largest energy in the velocity spectrum, the engagement frequency and the envelope spectrum; calculating the acceleration kurtosis according to the vibration acceleration signal; and carrying out fault diagnosis on the target gearbox according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis. The invention can improve the efficiency and reliability of gear fault diagnosis.
Description
Technical Field
The invention relates to the field of mechanical equipment state monitoring, in particular to a method and a system for automatically diagnosing gear faults of a gearbox.
Background
The gear box equipment has the characteristics of stable transmission, compact structure, flexibility and diversity, is widely applied to the industrial field, and meanwhile, the running state and the fault condition of the gear box are also widely concerned. The reason for this is that: a) the structure of the gear box is complex, the gear box usually consists of a plurality of groups of shafts, bearings and gears, the fault types are more, and the safe and stable operation of the whole equipment can be influenced when any part fails; b) the gear box has a compact structure, and cascading failures are easily caused by the failures, for example, the phenomenon that a plurality of pairs of gears are broken due to the fact that one gear box is broken; c) for critical gear drives or gearbox drives that are expensive to manufacture, the resulting downtime or downtime when a gear fails can result in significant economic loss. Therefore, the running state of the gear box is mastered in real time, and the gear fault is predicted in advance, so that the significance of safe and efficient production of enterprises is great. Vibration monitoring is widely accepted as an effective tool for detecting the state of a rotating machine, practitioners in the field of equipment state monitoring on vibration performance of different faults of a gearbox are researched in theory and practice, and the fault mechanism and the diagnosis and analysis method of the gearbox are relatively mature. According to the fault mechanism of the gearbox, different fault expressions can be realized when the gearbox has gear faults, bearing faults and shafting faults, for example, when the gears have tooth error, abrasion, pitting corrosion and tooth breakage, the meshing frequency of the gears is obviously increased when the gears have faults, part of faults can modulate the meshing frequency, and obvious side frequency components are generated beside the meshing frequency; when the bearing of the gear box fails, the phenomenon of impact machine modulation also occurs, but the modulation frequency is the bearing failure frequency; when the gear box has shafting related problems, the shafting related fault frequency (rotating frequency, harmonic frequency and the like) of the low-frequency part is mainly shown.
At present, the fault diagnosis mode of the gearbox is still mainly realized by manually analyzing vibration data, but the mode has low efficiency, different diagnosis conclusions can be caused by different manual diagnosis experiences, and the reliability of a diagnosis result is poor.
Disclosure of Invention
Based on the above, the embodiment of the invention provides a method and a system for automatically diagnosing gear faults of a gearbox, so as to improve the efficiency and reliability of gear fault diagnosis.
In order to achieve the purpose, the invention provides the following scheme:
a gearbox gear fault automatic diagnostic method comprising:
acquiring a vibration acceleration signal of a gear shaft in a target gear box and the meshing frequency of gears on the gear shaft;
determining a speed spectrum and an envelope spectrum of a gear shaft from the vibration acceleration signal;
determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum;
calculating an engagement frequency energy ratio, a side frequency energy ratio and a side frequency energy ratio according to the frequency component with the largest energy in the velocity spectrum, the engagement frequency and the envelope spectrum;
calculating an acceleration kurtosis according to the vibration acceleration signal;
carrying out fault diagnosis on the target gearbox according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result; the diagnosis result comprises a gear-free fault, a gear meshing fault, a gear local abrasion fault and a gear local broken tooth fault;
the fault diagnosis of the target gearbox is performed according to the modulation frequency identifier, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result, and the fault diagnosis specifically includes:
if the target gearbox meets a first judgment condition, determining that no gear fails; the first judgment condition is that the engagement frequency energy ratio is less than or equal to a first set threshold;
if the target gearbox meets a second judgment condition, determining that a gear meshing failure fault exists; the second judgment condition is that the engagement frequency energy ratio is greater than a first set threshold and the acceleration kurtosis is less than or equal to a second set threshold;
if the target gearbox meets a third judgment condition, determining that a first compound fault exists; the first compound fault is a fault of gear meshing failure and bearing damage compound; the third judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, and the modulation frequency identification is 0;
if the target gearbox meets a fourth judgment condition, determining that a second compound fault exists, wherein the second compound fault is a fault of gear meshing failure and bearing loosening combination; the fourth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, and the side frequency energy ratio is less than or equal to a third set threshold; the gear mesh failure comprises the gear mesh failure, the first compound failure, and the second compound failure;
if the target gearbox meets a fifth judgment condition, determining that a gear local abrasion fault exists; the fifth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is less than or equal to a fourth set threshold;
if the target gearbox meets the sixth judgment condition, determining that a local gear breakage fault of the gear exists; the sixth determination condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency flag is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is greater than a fourth set threshold.
Optionally, the obtaining of the vibration acceleration signal of the gear shaft in the target gear box and the meshing frequency of the gear on the gear shaft specifically includes:
collecting a vibration acceleration signal of a gear shaft by adopting a vibration acceleration sensor; the vibration acceleration sensor is arranged at the bearing position of a gear shaft in the target gearbox;
acquiring the rotation frequency of a gear shaft and the number of gear teeth on the gear shaft;
and calculating the meshing frequency of the gears on the corresponding gear shafts according to the rotating frequency of the gear shafts and the number of the gear teeth.
Optionally, the determining the speed spectrum and the envelope spectrum of the gear shaft according to the vibration acceleration signal specifically includes:
carrying out band-pass filtering on the vibration acceleration signal, and integrating the vibration acceleration signal subjected to the band-pass filtering to obtain a speed signal;
carrying out fast Fourier transform on the speed signal to obtain a speed spectrum;
carrying out high-pass filtering on the vibration acceleration signal, and carrying out Hilbert transform on the vibration acceleration signal subjected to the high-pass filtering to obtain an envelope signal;
and carrying out fast Fourier transform on the envelope signal to obtain an envelope spectrum.
Optionally, the determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum specifically includes:
calculating the frequency component with the maximum energy in the envelope spectrum by adopting a narrow-band window;
and determining the modulation frequency identification according to the relationship among the rotating frequency of the gear shaft, the meshing frequency and the frequency component with the maximum energy in the envelope spectrum.
Optionally, the calculating, according to the frequency component with the largest energy in the velocity spectrum, the engagement frequency, and the envelope spectrum, an engagement frequency energy ratio, a side frequency energy ratio, and a side frequency energy ratio specifically includes:
calculating the proportion of the sum of the energy of one time of the meshing frequency and the energy of two times of the meshing frequency in the energy of the whole frequency band according to the speed spectrum and the meshing frequency to obtain the energy proportion of the meshing frequency;
calculating a first energy ratio and a second energy ratio according to the frequency component with the largest energy in the velocity spectrum, the meshing frequency and the envelope spectrum, and determining the maximum value of the first energy ratio and the second energy ratio as an edge frequency energy rate; the first energy ratio is the ratio of the energy of the side frequency of one time of the meshing frequency to the energy of one time of the meshing frequency; the second energy ratio is the ratio of the energy of the side frequency of twice the meshing frequency to the energy of twice the meshing frequency;
calculating the ratio of the sum of the first energy and the second energy in the energy of the whole frequency band according to the frequency component with the largest energy in the velocity spectrum, the meshing frequency and the envelope spectrum to obtain the ratio of the side frequency energy rate; the first energy is the sum of the energy of one time of the meshing frequency and the energy of the side frequency of one time of the meshing frequency; the second energy is the sum of energy at twice the meshing frequency and energy at the side frequency at twice the meshing frequency.
Optionally, the determining a modulation frequency identifier according to a relationship among the frequency conversion of the gear shaft, the meshing frequency, and a frequency component with the maximum energy in the envelope spectrum specifically includes:
when the frequency component with the maximum energy in the envelope spectrum is equal to the rotating frequency of the gear shaft, determining that the modulation frequency identifier is 1;
when the meshing frequency is an integral multiple of the frequency component with the largest energy in the envelope spectrum and the frequency conversion frequency of the gear shaft with the largest energy in the envelope spectrum is less than 0.5 time, determining that the modulation frequency is marked as 1;
when the meshing frequency is not an integral multiple of the frequency component with the largest energy in the envelope spectrum, the modulation frequency identifier is determined to be 0.
Optionally, the first set threshold is 0.4; the second set threshold is 2.8; the third set threshold is 0.5; the fourth setting threshold is 0.5.
The invention also provides an automatic fault diagnosis system for gears of a gearbox, which comprises:
the data acquisition module is used for acquiring a vibration acceleration signal of a gear shaft in the target gear box and the meshing frequency of gears on the gear shaft;
the speed spectrum envelope spectrum determining module is used for determining a speed spectrum and an envelope spectrum of the gear shaft according to the vibration acceleration signal;
the first index determining module is used for determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum;
the second index determining module is used for calculating an engagement frequency energy ratio, a side frequency energy ratio and a side frequency energy ratio according to the frequency component with the maximum energy in the velocity spectrum, the engagement frequency and the envelope spectrum;
the third index determining module is used for calculating the acceleration kurtosis according to the vibration acceleration signal;
the fault diagnosis module is used for carrying out fault diagnosis on the target gearbox according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate, the side frequency energy ratio and the acceleration kurtosis to obtain a diagnosis result; the diagnosis result comprises a gear-free fault, a gear meshing fault, a gear local abrasion fault and a gear local broken tooth fault;
the fault diagnosis of the target gearbox is performed according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis, so as to obtain a diagnosis result, and the method specifically comprises the following steps:
if the target gearbox meets a first judgment condition, determining that no gear fails; the first judgment condition is that the engagement frequency energy ratio is less than or equal to a first set threshold;
if the target gearbox meets a second judgment condition, determining that a gear meshing failure fault exists; the second judgment condition is that the engagement frequency energy ratio is greater than a first set threshold and the acceleration kurtosis is less than or equal to a second set threshold;
if the target gearbox meets a third judgment condition, determining that a first compound fault exists; the first compound fault is a fault of gear meshing failure and bearing damage compound; the third judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, and the modulation frequency identification is 0;
if the target gearbox meets a fourth judgment condition, determining that a second compound fault exists, wherein the second compound fault is a fault of gear poor meshing and bearing loosening compounding; the fourth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, and the side frequency energy ratio is less than or equal to a third set threshold; the gear mesh failure comprises the gear mesh failure, the first compound failure, and the second compound failure;
if the target gearbox meets a fifth judgment condition, determining that a gear local abrasion fault exists; the fifth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is less than or equal to a fourth set threshold;
if the target gearbox meets the sixth judgment condition, determining that a local gear breakage fault of the gear exists; the sixth determination condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency flag is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is greater than a fourth set threshold.
Optionally, the data obtaining module specifically includes:
the vibration data acquisition unit is used for acquiring a vibration acceleration signal of the gear shaft by adopting a vibration acceleration sensor; the vibration acceleration sensor is arranged at the position of a gear shaft bearing in the target gearbox;
the static parameter acquisition unit is used for acquiring the rotation frequency of the gear shaft and the number of gear teeth on the gear shaft;
and the meshing frequency calculation unit is used for calculating the meshing frequency of the gears on the corresponding gear shafts according to the rotating frequency of the gear shafts and the number of the gear teeth.
Compared with the prior art, the invention has the beneficial effects that:
the embodiment of the invention provides a method and a system for automatically diagnosing gear fault of a gear box, which are used for calculating five characteristic indexes, namely modulation frequency identification, meshing frequency energy ratio, edge frequency energy ratio and acceleration kurtosis, according to a vibration acceleration signal and a speed spectrum and an envelope spectrum determined by the vibration acceleration signal, and automatically diagnosing the fault of a target gear box according to the five calculated characteristic indexes, thereby solving the problems of low manual diagnosis efficiency and inconsistent diagnosis conclusion caused by non-uniform manual experience, and improving the efficiency and reliability of gear fault diagnosis.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for automatically diagnosing gear faults of a gearbox according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a specific implementation process of an automatic diagnosis method for gear faults of a gearbox according to an embodiment of the invention;
fig. 3 is a schematic diagram of a method for calculating an energy ratio of an engagement frequency according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a method for calculating a side-frequency energy ratio according to an embodiment of the present invention;
fig. 5 is a schematic diagram illustrating a method for calculating an edge frequency energy rate according to an embodiment of the present invention;
FIG. 6A is a schematic frequency spectrum diagram of a gear mesh fault provided by an embodiment of the present invention;
FIG. 6B is a graphical illustration of a frequency spectrum of a localized fretting failure of a gear provided by an embodiment of the present invention;
FIG. 6C is a schematic frequency spectrum diagram illustrating a gear local tooth breakage fault according to an embodiment of the present invention;
FIG. 7A is a spectrum diagram of a waveform 1 according to an embodiment of the present invention;
FIG. 7B is a spectrum diagram of waveform 2 according to an embodiment of the present invention;
FIG. 7C is a graph of the spectrum of waveform 3 according to an embodiment of the present invention;
FIG. 7D is a graph of the spectrum of waveform 4 provided by an embodiment of the present invention;
FIG. 8 is a block diagram of an automatic diagnostic system for gear failure of a gearbox according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
The fault diagnosis mode of the existing gearbox is mainly realized in a manual mode, and the problems of low efficiency and poor reliability exist. Under the background of mature fault diagnosis mechanism of the gearbox and expert diagnosis experience, it is very meaningful to form an automatic fault diagnosis method of the gearbox by digitizing and characterizing fault expressions. Therefore, the embodiment provides an automatic diagnosis method for gear fault of a gearbox, which can automatically judge the fault of the gearbox when the gearbox is abnormal under the condition that the parameters (the number of teeth, the rotating speed and the like) of the gearbox are known, and obtain the approximate direction of the fault of the gearbox, thereby improving the diagnosis efficiency and the diagnosis reliability of the fault of the gearbox.
FIG. 1 is a flow chart of a method for automatically diagnosing gear faults of a gearbox according to an embodiment of the invention. Referring to fig. 1, the automatic diagnosis method for gear fault of gearbox of the embodiment comprises the following steps:
step 101: and acquiring a vibration acceleration signal of a gear shaft in the target gearbox and the meshing frequency of gears on the gear shaft.
The step 101 specifically includes:
1) collecting a vibration acceleration signal of a gear shaft by adopting a vibration acceleration sensor; the vibration acceleration sensor is arranged at the position of a gear shaft bearing in the target gear box.
2) And acquiring the rotation frequency of the gear shaft and the number of gear teeth on the gear shaft.
3) And calculating the meshing frequency of the gears on the corresponding gear shafts according to the rotating frequency of the gear shafts and the number of the gear teeth, wherein the calculation formula is as follows:
f GMF =rotate_freq*GTnum （1）
wherein,f GMF representing the meshing frequency of the gears;rotate_freqrepresenting the rotational frequency of the gear shaft;GTnumindicating the number of gear teeth.
Step 102: and determining a speed spectrum and an envelope spectrum of the gear shaft according to the vibration acceleration signal.
The step 102 specifically includes:
1) carrying out band-pass filtering on the vibration acceleration signal, and integrating the vibration acceleration signal subjected to band-pass filtering to obtain a speed signal; performing Fast Fourier Transform (FFT) on the velocity signal to obtain a velocity spectrumVel_f_sig. It is composed ofIn the middle, the upper limit cut-off frequency of the adopted band-pass filter is 1KHz, and the lower limit cut-off frequency is 10 Hz.
2) Carrying out high-pass filtering on the vibration acceleration signal, and carrying out Hilbert transform on the vibration acceleration signal subjected to the high-pass filtering to obtain an envelope signal; performing Fast Fourier Transform (FFT) on the envelope signal to obtain an envelope spectrumEnve_f_sig. Wherein, the lower limit cut-off frequency of the adopted high-pass filter is 10 Hz.
Step 103: and determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum.
The step 103 specifically includes:
1) and calculating the frequency component with the maximum energy in the envelope spectrum by adopting a narrow-band window.
2) And determining a modulation frequency identifier mod _ flag according to the relationship among the rotating frequency of the gear shaft, the meshing frequency and the frequency component with the largest energy in the envelope spectrum. The method specifically comprises the following steps:
when the frequency component with the maximum energy in the envelope spectrum is equal to the frequency conversion of the gear shaft, determining that the modulation frequency identifier is 1, namely mod _ flag = 1; when the meshing frequency is an integral multiple of the frequency component with the largest energy in the envelope spectrum and the frequency component with the largest energy in the envelope spectrum is less than 0.5 times of the rotation frequency of the gear shaft, determining that the modulation frequency is marked as 1, namely mod _ flag = 1; when the meshing frequency is not an integral multiple of the frequency component with the largest energy in the envelope spectrum, it is determined that the modulation frequency flag is 0, i.e., mod _ flag = 0.
Step 104: and calculating the engagement frequency energy ratio, the side frequency energy ratio and the side frequency energy ratio according to the frequency component with the maximum energy in the velocity spectrum, the engagement frequency and the envelope spectrum.
The step 104 specifically includes:
1) calculating the proportion of the sum of the energy of one time of the meshing frequency and the energy of two times of the meshing frequency in the energy of the whole frequency band according to the velocity spectrum and the meshing frequency to obtain the meshing frequency energy proportion Gmf _ energy _ ratio, wherein the calculation formula is as follows:
wherein,Vel_f_sig（f GME ) Representing mesh frequency in velocity spectrumf GME A corresponding amplitude value;Vel_f_sig（2*f GME ) Representing the double mesh frequency 2 in the velocity spectrumf GME A corresponding amplitude value;Vel_f_sig（f) Representing frequencies within the entire frequency band in the velocity spectrumfA corresponding amplitude value; (Vel_f_sig（f GME ））2Energy representing one mesh frequency; (Vel_f_sig（2*f GME ））2Represents energy at twice the meshing frequency;
represents the entire band energy;f srepresenting the signal sampling frequency.
2) And calculating a first energy ratio Gmf _1_ SER and a second energy ratio Gmf _2_ SER according to the frequency component with the largest energy in the velocity spectrum, the meshing frequency and the envelope spectrum, and determining the maximum value of the first energy ratio and the second energy ratio as the side-frequency energy rate SER. The first energy ratio Gmf _1_ SER is a ratio of energy of a side frequency of one time of the meshing frequency to energy of one time of the meshing frequency; the second energy ratio Gmf _2_ SER is a ratio of energy of a side frequency of twice the meshing frequency to energy of twice the meshing frequency. The calculation formulas of the first energy ratio Gmf _1_ SER, the second energy ratio Gmf _2_ SER, the side-frequency energy rate and the side-frequency energy rate SER are as follows:
wherein,Enve_MaxFreqrepresenting the frequency component with the largest energy in the envelope spectrum;kto representEnve_MaxFreqThe coefficient of (a);Vel_f_sig（f GME +k*Enve_MaxFreq) Representing mesh frequency in velocity spectrumf GME Andkmultiple ofEnve_MaxFreqThe amplitude corresponding to the sum of the frequencies of (a);
energy representing a side frequency of one mesh frequency;Vel_f_sig（2*f GME +k*Enve_MaxFreq) Representing the double mesh frequency 2 in the velocity spectrumf GME Andkmultiple ofEnve_MaxFreqThe amplitude corresponding to the sum of the frequencies of (a);
3) Calculating the ratio of the Sum of the first energy and the second energy in the energy of the whole frequency band according to the frequency component with the largest energy in the velocity spectrum, the meshing frequency and the envelope spectrum to obtain the ratio of the side frequency energy rate to Sum _ side _ ratio; the first energy is the sum of the energy of one time of the meshing frequency and the energy of the side frequency of one time of the meshing frequency; the second energy is the sum of energy at twice the meshing frequency and energy at the side frequency at twice the meshing frequency. The calculation formula of the side-frequency energy rate ratio Sum _ side _ ratio is as follows:
step 105: and calculating the acceleration kurtosis according to the vibration acceleration signal. The calculation formula of the acceleration kurtosis Acc _ kurtosis is as follows:
wherein,acc_sig i representing the first of the vibration acceleration signals measured by the vibration acceleration sensor at a single timeiSampling values; n represents the number of sampling points, i.e., the sampling length of the vibration acceleration signal.
Step 106: carrying out fault diagnosis on the target gearbox according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result; the diagnosis results include a no gear fault, a gear meshing fault, a gear local abrasion fault and a gear local tooth breakage fault.
The step 106 specifically includes:
if the target gearbox meets a first judgment condition, determining that no gear fails; the first judgment condition is that the engagement frequency energy ratio is less than or equal to a first set threshold.
If the target gearbox meets a second judgment condition, determining that a gear meshing failure fault exists; the second judgment condition is that the engagement frequency energy ratio is greater than a first set threshold and the acceleration kurtosis is less than or equal to a second set threshold.
If the target gearbox meets a third judgment condition, determining that a first compound fault exists; the first compound fault is a fault of gear meshing failure and bearing damage compound; the third determination condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, and the modulation frequency flag is 0.
If the target gearbox meets a fourth judgment condition, determining that a second compound fault exists, wherein the second compound fault is a fault of gear meshing failure and bearing loosening combination; the fourth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, and the side frequency energy ratio is less than or equal to a third set threshold; the gear mesh failure includes the gear mesh failure, the first compound failure, and the second compound failure.
If the target gearbox meets a fifth judgment condition, determining that a gear local abrasion fault exists; the fifth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is less than or equal to a fourth set threshold.
If the target gearbox meets the sixth judgment condition, determining that a local gear breakage fault of the gear exists; the sixth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is greater than a fourth set threshold.
Wherein the first set threshold is 0.4; the second set threshold is 2.8; the third set threshold is 0.5; the fourth set threshold is 0.5.
In practical application, one specific implementation process of the automatic diagnosis method for gear faults of the gearbox is as follows:
in order to solve the problems that the manual diagnosis efficiency of the fault of the gearbox is low, the diagnosis conclusion is inconsistent due to the fact that manual experience is not uniform, and the like, the automatic diagnosis method for the fault of the gear of the gearbox of the embodiment is characterized in that firstly, a vibration acceleration sensor is installed at each shaft bearing position according to the structure of the gearbox, vibration signals of the gearbox are collected in real time, and the vibration signals at least comprise: velocity signal, acceleration, envelope signal; extracting corresponding characteristic indexes (gear fault identification indexes) in the time domain and the frequency domain of the collected signals by combining a gear fault mechanism and the typical characteristics of gear fault vibration; and finally, automatically identifying the gear fault of the gearbox through the characteristic indexes. The method comprises the following concrete implementation processes:
the method comprises the following steps: collecting vibration measuring point signals of the gear box and collecting static parameters of the gear box.
According to the monitoring requirement, a vibration acceleration sensor is arranged at the position of the gear shaft bearing to be monitored, and a vibration acceleration signal of the measuring point is collected in real timeacc_sig(ii) a Simultaneously obtain the frequency of the gear shaftrotate_freqAnd the number of gear teeth on the gear shaftGTnumAnd calculating the meshing frequency of the gears on the gear shaft according to the formula (1)f GMF (in the case where there are a plurality of pairs of gear shafts, the gear pair is selected for each gear shaftThe number of gear teeth of the gear pair calculates the corresponding meshing frequency, and the present embodiment takes one gear pair on the gear shaft as an example, and the gear fault diagnosis methods of other gear pairs are the same).
Step two: processing raw vibration acceleration signals
For original vibration acceleration signalacc_sigPerforming band-pass filtering, wherein the upper limit cut-off frequency of the filter is 1KHz and the lower limit cut-off frequency of the filter is 10Hz, and integrating the filtered signals to obtain speed signalsvel_sigAnd FFT is carried out on the speed signal to obtain a speed spectrum Vel _ f _ sig.
For original vibration acceleration signalacc_sigCarrying out high-pass filtering, wherein the lower limit cut-off frequency of the filter is 1KHz, and carrying out Hilbert conversion on the filtered signal to obtain an envelope signalEnve_sigAnd FFT is carried out on the speed signal to obtain an envelope spectrum Enve _ f _ sig.
Step three: and extracting corresponding gear fault identification indexes according to the gear fault mechanism and the vibration characteristics of the gearbox.
When a gear has tooth profile error, abrasion, pitting corrosion and broken teeth, the meshing frequency of the gear is obviously increased when the gear usually breaks down, and the edge frequency amplitude around the meshing frequency is very small or has no edge frequency component when the gear has tooth profile error and is uniformly abraded; when a gear has local faults such as local pitting corrosion and local abrasion, side frequency components usually appear around the meshing frequency, the side frequency components are the rotating frequency of the fault gear, and the side frequency amplitude is high but the number is small; when local broken teeth occur on the gear, side frequency components usually occur around the meshing frequency, the side frequency components are fault gear rotating frequency, and the side frequency amplitude is high and the number is large. For typical spectral characteristics of different gear faults, corresponding characteristic indexes can be extracted from the monitoring signals.
The first characteristic index is a modulation frequency identifier mod _ flag, and the calculation method is as follows:
in thatEnve_f_sigUsing slidingWnumObtaining the frequency component with the maximum energy of the sliding narrow-band window by the multiple narrow-band windowEnve_MaxFreq. Frequency conversion by gear shaftrotate_freqFrequency of engagementf GMF And the frequency component Enve _ MaxFreq with the largest energy in the envelope spectrum, determines the modulation frequency flag mod _ flag: when Enve _ MaxFreq is equal torotate_freqMod _ flag = 1; when in usef GMF Is an integer multiple of Enve _ MaxFreq and Enve _ MaxFreq is less than 0.5 timesrotate_freqMod _ flag = 1; when in usef GMF Mod _ flag =0 when not an integer multiple of Enve _ MaxFreq.
The calculation process of Enve _ MaxFreq is as follows:
frequency sequence of envelopesf_enve_listTo (1) anA frequency componentf n ，f n Is/are as followsmThe frequency sequence corresponding to the frequency in the narrow band window is set as [ 2 ]m*f n -2*∆f ：m*f n -2*∆f]Corresponding to frequencyf n The corresponding sliding narrow-band window energy calculation formula is as follows:
wherein, ΔfIs the spectral resolution of the envelope spectrum;Enve_f_sig(m*f n -j*∆f) For frequency of envelope spectrumm* f n -j*∆fThe amplitude of (d);mto representf n The coefficient of (a);jrepresent afThe coefficient of (a);Wnumdetermined by the calculation effect, generally set to 4; maximum sliding narrowband window energymax(Energy_f n ) The corresponding frequency isEnve_MaxFreq。
The second characteristic indicator is the engagement frequency energy ratio Gmf _ energy _ ratio, and the calculation formula is shown in formula (2).
And thirdly, the third characteristic index is the side frequency energy rate SER, and the calculation formula is shown as a formula (3).
And fourthly, the fourth characteristic index is the side frequency energy ratio Sum _ side _ ratio, and the calculation formula is shown as formula (4).
Fifthly, the fifth characteristic index is acceleration kurtosis Acc _ kurtosis, and the calculation formula is shown as formula (5).
Step four: and automatically identifying gear faults of the gearbox.
According to the characteristic index extracted from the gear box signal, the following fault judgment condition is formed according to the relation between the characteristic value and the threshold value thereof (wherein each characteristic value threshold value is obtained by counting the characteristic values of the accumulated case data, and the first set threshold valuethreshold1 is 0.4, the second set thresholdthreshold2 is 2.8, and the third setting thresholdthreshold3 value of 0.5, fourth set thresholdthreshold4, the value is 0.5), the operation condition of the gearbox is judged according to the final satisfied condition of each condition, and the following operation state and fault type of the gearbox can be judged:
1) no gear failure: if the gearbox box has no gear fault, the meshing frequency and harmonic frequency energy thereof are in normal level, so the judgment condition is as follows: a) engagement frequency energy ratioGmf_energy_ratioLess than or equal to a first set thresholdthreshold1；
2) Gear meshing failure: considering the gearbox compound fault situation, the gear meshing fault can be divided into the following three situations:
case 1: the gear meshing frequency and harmonic frequency energy are high, but the acceleration has no obvious impact, so that no compound fault is caused, and the simple poor meshing is caused (namely, the gear poor meshing fault), and the judgment conditions are as follows:
a) engagement frequency energy ratioGmf_energy_ratioGreater than a first set thresholdthreshold1；b)
Acceleration kurtosisAcc_kurtosisLess than or equal to a specified threshold value and a second set threshold valuethreshold2；
Case 2: the gear meshing frequency and the harmonic frequency energy thereof are high, but the acceleration has impact, the modulation frequency is a non-gear shaft frequency conversion component, the condition is a composite fault, and the modulation frequency is the non-gear shaft frequency conversion component, and the composite condition (a first composite fault) of gear meshing failure and bearing damage is possible, and the judgment condition is as follows:
a)1 to 2 times of meshing frequency energy ratio Gmf _ energy _ ratio is greater than a first set threshold valuethreshold1；b) The acceleration kurtosis Acc _ kurtosis is greater than a second set thresholdthreshold2; c) modulation frequency identification mod _ flag = = 0;
case 3: the gear meshing frequency and the harmonic frequency energy thereof are high, but the acceleration has impact, the modulation frequency is a gear shaft frequency rotation component, but no side frequency component of obvious gear shaft frequency rotation exists near the meshing frequency, the condition is a composite fault, the modulation frequency is the gear shaft frequency rotation component, the gear local fault or the bearing looseness can be caused, but no side frequency component of obvious gear shaft frequency rotation exists near the meshing frequency, therefore, the gear local fault is eliminated, the condition can be a composite condition (a second composite fault) of the gear meshing failure and the bearing looseness, and the judgment condition is as follows:
a)1 to 2 times of meshing frequency energy ratio Gmf _ energy _ ratio is greater than a first set threshold valuethreshold1; b) the acceleration kurtosis Acc _ kurtosis is greater than a second set thresholdthreshold2; c) modulation frequency identification mod _ flag = = 1; d) the side frequency energy rate ratio Sum _ side _ ratio is less than or equal to a third set thresholdthreshold3。
3) Local fretting failures (wear, pitting) of gears: the meshing frequency and harmonic frequency energy of the gear are high, the acceleration has impact, the modulation frequency is a gear shaft frequency rotation component, a side frequency component of the gear shaft frequency rotation exists near the meshing frequency, because the severity of the local fault of the gear is in direct proportion to the energy of the side frequency component of the meshing frequency, the meshing frequency energy is still dominant when the local fault occurs in the gear, the side frequency energy is lower than the meshing frequency energy, and the judgment condition is as follows:
a)1 to 2 times of the energy proportion Gmf _ energy _ ratio of the meshing frequency is greater than a first set threshold valuethreshold1; b) the acceleration kurtosis Acc _ kurtosis is greater than a second set thresholdthreshold2; c) modulation frequency identification mod _ flag = = 1; d) the side frequency energy rate ratio Sum _ side _ ratio is greater than a third set thresholdthreshold3; e) the side frequency energy rate SER is less than or equal to a third set threshold valuethreshold3。
4) Local broken tooth fault of the gear: the meshing frequency and harmonic frequency energy of the gear are high, the acceleration has impact, the modulation frequency is a gear shaft frequency rotation component, a side frequency component of the gear shaft frequency rotation exists near the meshing frequency, the severity of local fault of the gear is in direct proportion to the energy of the side frequency component of the meshing frequency, the side frequency energy of the gear is higher than the energy of the meshing frequency when local fault of the gear occurs, and the judgment condition is that the side frequency energy of the gear is higher than the energy of the meshing frequency
a)1 to 2 times of meshing frequency energy ratio Gmf _ energy _ ratio is greater than a first set threshold valuethreshold1; b) the acceleration kurtosis Acc _ kurtosis is greater than a second set thresholdthreshold2; c) modulation frequency identification mod _ flag = = 1; d) the side frequency energy rate ratio Sum _ side _ ratio is greater than a third set thresholdthreshold3; e) the side frequency energy rate SER is larger than a third set threshold valuethreshold3。
A flow chart of a specific implementation mode of the automatic diagnosis method for the gear fault of the gearbox is shown in FIG. 2. Firstly, mounting a vibration acceleration sensor at a bearing position of a gear box, acquiring a vibration acceleration signal of the gear box in real time, carrying out band-pass filtering and integration on an original vibration acceleration signal to obtain a speed signal, and carrying out FFT (fast Fourier transform) on the speed signal to obtain a speed spectrum; meanwhile, filtering and Hilbert transforming the original vibration acceleration signal to obtain an envelope signal, and performing FFT (fast Fourier transform) on the envelope signal to obtain an envelope spectrum; secondly, acquiring the rotation frequency rotate _ freq of the gear shaft and the gear tooth number GTnum on the gear shaft, and calculating the meshing frequency of the gears on the gear shaftf GMF (ii) a Thirdly, through information such as the gear shaft rotational frequency and the gear meshing frequency that acquire, extract gear box fault identification index in acceleration, speed, the envelope signal of gathering, include: an engagement frequency energy ratio Gmf _ energy _ ratio of 1 to 2 times of speed, an acceleration kurtosis Acc _ kurtosis, a modulation frequency identification mod _ flag, a side frequency energy ratio Sum _ side _ ratio and a side frequency energy ratio SER; finally, combining a gear fault mechanism and a typical gear box fault characteristic, forming a gear fault judgment condition according to the relationship between a gear box fault identification index and a threshold value thereof, achieving the purpose of automatic diagnosis of the gear box fault, wherein the fault identification comprises the following steps: gear mesh failure, gear local erosion failure (pitting, wear) and gear local tooth breakage failure.
A calculation method of the engagement frequency energy ratio Gmf _ energy _ ratio of 1 to 2 times is shown in fig. 3, specifically, Gmf _ energy _ ratio = (engagement frequency energy)/(energy of the entire band). The index represents the ratio of the energy of 1-fold and 2-fold meshing frequency to the energy of the entire frequency band, and may reflect the energy level of the meshing frequency.
Fig. 4 shows a method for calculating the side-frequency energy ratio Sum _ side _ ratio, specifically Sum _ side _ ratio = (or =) =: (or a ratio of side-frequency energy rates) in a method for calculating the side-frequency energy ratio Sum _ side _ ratiof GMF And its side frequency energy +2xf GMF And its side-band energy)/(whole-band energy). The index represents the ratio of the sum of the energy of 1-fold meshing frequency and its side-frequency components and the energy of 2-fold meshing frequency and its side-frequency components to the energy of the entire frequency band, and reflects the level of the side-frequency components present beside the meshing frequency of the gear box.
The calculation method of the side-frequency energy rate SER is shown in FIG. 5, and the index represents 1-fold meshing frequencyf GMF Side frequency energy andf GMF energy ratio Gmf _1_ SER and 2 times meshing frequency 2xf GMF Side frequency energy and 2xf GMF The largest ratio of the energy ratios Gmf _2_ SER, which is used to reflect the severity of the local gear failure. Specifically, Gmf _1_ SER = (Gmf _1_ SER =: (Gmf _1_ SER =) (Gmf))f GMF Side frequency energy)/(f GMF Energy); gmf _2_ SER = (2 ×) (ii)f GMF Side frequency energy)/(2 xf GMF Energy); SER =MAX（Gmf_1_SER，Gmf_2_SER）。
Gear mesh failure is manifested by higher gear mesh frequency and its harmonic energy, as shown in fig. 6A; local abrasion failure (abrasion, pitting) of the gear is represented by high meshing frequency of the gear and harmonic frequency energy thereof, and side frequency components of gear shaft rotation frequency exist near the meshing frequency, as shown in fig. 6B; the local tooth breakage fault of the gear is represented by that the gear meshing frequency and harmonic frequency energy thereof are high, a side frequency component of the gear shaft rotation frequency exists near the meshing frequency, the side frequency energy is high compared with the meshing frequency energy, and the number of side frequencies is large, as shown in fig. 6C.
The comparison results of the partial gear fault frequency spectrum, the fault identification indexes and the fault identification conditions are shown in table 1. The spectrograms of waveform 1, waveform 2, waveform 3 and waveform 4 in table 1 are shown in fig. 7A, 7B, 7C and 7D, respectively.
TABLE 1 comparative results
| Input shaft velocity waveform | Engagement frequency energy ratio | Acceleration kurtosis | Modulation frequency identification | Side frequency energy ratio | Side frequency energy rate | Type of |
| Wave form | ||||||
| 1 | 0.235 | 1.586 | 1 | 0.257 | 0.564 | Failure of |
| Wave form | ||||||
| 2 | 0.458 | 2.934 | 1 | 0.566 | 0.314 | Local wear failure of gears |
| Waveform 3 | 0.413 | 4.115 | 1 | 0.812 | 0.589 | Local tooth breakage fault of |
| Waveform | ||||||
| 4 | 0.718 | 1.223 | 0 | 0.738 | 0.223 | Gear mesh failure |
The comparison condition of the table 1 shows that the gear box fault identification method provided by the embodiment can effectively identify common fault types of the gear box and achieve a good effect.
The present invention also provides a gearbox gear fault automatic diagnostic system, see fig. 8, the system comprising:
and the data acquisition module 201 is used for acquiring a vibration acceleration signal of a gear shaft in the target gearbox and the meshing frequency of gears on the gear shaft.
And a speed spectrum envelope spectrum determination module 202 for determining a speed spectrum and an envelope spectrum of the gear shaft from the vibration acceleration signal.
A first index determining module 203, configured to determine a modulation frequency identifier according to the meshing frequency and a frequency component with the largest energy in the envelope spectrum.
And a second index determining module 204, configured to calculate an engagement frequency energy ratio, a side frequency energy ratio, and a side frequency energy ratio according to the frequency component with the largest energy in the velocity spectrum, the engagement frequency, and the envelope spectrum.
And a third index determining module 205, configured to calculate an acceleration kurtosis according to the vibration acceleration signal.
A fault diagnosis module 206, configured to perform fault diagnosis on the target gearbox according to the modulation frequency identifier, the meshing frequency energy ratio, the side frequency energy rate, the side frequency energy ratio, and the acceleration kurtosis, so as to obtain a diagnosis result; the diagnosis results include a no gear fault, a gear meshing fault, a gear local abrasion fault and a gear local tooth breakage fault.
In an example, the data obtaining module 201 specifically includes:
the vibration data acquisition unit is used for acquiring a vibration acceleration signal of the gear shaft by adopting a vibration acceleration sensor; the vibration acceleration sensor is arranged at the position of a gear shaft bearing in the target gear box.
And the static parameter acquisition unit is used for acquiring the rotation frequency of the gear shaft and the number of gear teeth on the gear shaft.
And the meshing frequency calculation unit is used for calculating the meshing frequency of the gears on the corresponding gear shafts according to the rotating frequency of the gear shafts and the number of the gear teeth.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (7)
1. A method for automatically diagnosing gear faults of a gearbox is characterized by comprising the following steps:
acquiring a vibration acceleration signal of a gear shaft in a target gear box and the meshing frequency of gears on the gear shaft;
determining a speed spectrum and an envelope spectrum of a gear shaft from the vibration acceleration signal;
determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum;
calculating an engagement frequency energy ratio, a side frequency energy ratio and a side frequency energy ratio according to the frequency component with the largest energy in the velocity spectrum, the engagement frequency and the envelope spectrum;
calculating an acceleration kurtosis according to the vibration acceleration signal;
carrying out fault diagnosis on the target gearbox according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result; the diagnosis results comprise a gear-free fault, a gear meshing fault, a gear local abrasion fault and a gear local tooth breakage fault;
the fault diagnosis of the target gearbox is performed according to the modulation frequency identifier, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result, and the fault diagnosis specifically includes:
if the target gearbox meets a first judgment condition, determining that no gear fails; the first judgment condition is that the engagement frequency energy ratio is less than or equal to a first set threshold;
if the target gearbox meets a second judgment condition, determining that a gear meshing failure fault exists; the second judgment condition is that the engagement frequency energy ratio is greater than a first set threshold and the acceleration kurtosis is less than or equal to a second set threshold;
if the target gearbox meets a third judgment condition, determining that a first compound fault exists; the first compound fault is a fault of gear meshing failure and bearing damage compound; the third judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, and the modulation frequency identification is 0;
if the target gearbox meets a fourth judgment condition, determining that a second compound fault exists, wherein the second compound fault is a fault of gear meshing failure and bearing loosening combination; the fourth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, and the side frequency energy ratio is less than or equal to a third set threshold; the gear mesh failure comprises the gear mesh failure, the first compound failure, and the second compound failure;
if the target gearbox meets a fifth judgment condition, determining that a gear local abrasion fault exists; the fifth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is less than or equal to a fourth set threshold;
if the target gearbox meets the sixth judgment condition, determining that a local gear breakage fault of the gear exists; the sixth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is greater than a fourth set threshold;
the determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum specifically includes:
calculating the frequency component with the maximum energy in the envelope spectrum by adopting a narrow-band window;
determining a modulation frequency identifier according to the relationship among the rotating frequency of the gear shaft, the meshing frequency and the frequency component with the maximum energy in the envelope spectrum;
the determining of the modulation frequency identifier by the relationship among the rotation frequency of the gear shaft, the meshing frequency and the frequency component with the maximum energy in the envelope spectrum specifically comprises:
when the frequency component with the maximum energy in the envelope spectrum is equal to the rotating frequency of the gear shaft, determining that the modulation frequency identifier is 1;
when the meshing frequency is an integral multiple of the frequency component with the largest energy in the envelope spectrum and the frequency conversion frequency of the gear shaft with the largest energy in the envelope spectrum is less than 0.5 time, determining that the modulation frequency is marked as 1;
when the meshing frequency is not an integral multiple of the frequency component with the largest energy in the envelope spectrum, the modulation frequency is determined to be 0.
2. The method for automatically diagnosing the gear fault of the gearbox according to claim 1, wherein the step of acquiring the vibration acceleration signal of the gear shaft in the target gearbox and the meshing frequency of the gears on the gear shaft comprises the following steps:
collecting a vibration acceleration signal of a gear shaft by adopting a vibration acceleration sensor; the vibration acceleration sensor is arranged at the position of a gear shaft bearing in the target gearbox;
acquiring the rotation frequency of a gear shaft and the number of gear teeth on the gear shaft;
and calculating the meshing frequency of the gears on the corresponding gear shafts according to the rotating frequency of the gear shafts and the number of the gear teeth.
3. The method for automatically diagnosing the gear fault of the gearbox according to claim 1, wherein the step of determining a speed spectrum and an envelope spectrum of a gear shaft by the vibration acceleration signal specifically comprises the following steps:
carrying out band-pass filtering on the vibration acceleration signal, and integrating the vibration acceleration signal subjected to band-pass filtering to obtain a speed signal;
carrying out fast Fourier transform on the speed signal to obtain a speed spectrum;
carrying out high-pass filtering on the vibration acceleration signal, and carrying out Hilbert transform on the vibration acceleration signal subjected to the high-pass filtering to obtain an envelope signal;
and carrying out fast Fourier transform on the envelope signal to obtain an envelope spectrum.
4. The method for automatically diagnosing the gear fault of the gearbox according to the claim 1, wherein the step of calculating the engagement frequency energy ratio, the side frequency energy ratio and the side frequency energy ratio according to the frequency component with the largest energy in the speed spectrum, the engagement frequency and the envelope spectrum specifically comprises the following steps:
calculating the proportion of the sum of the energy of one time of the meshing frequency and the energy of two times of the meshing frequency in the energy of the whole frequency band according to the speed spectrum and the meshing frequency to obtain the energy proportion of the meshing frequency;
calculating a first energy ratio and a second energy ratio according to the frequency component with the largest energy in the velocity spectrum, the meshing frequency and the envelope spectrum, and determining the maximum value of the first energy ratio and the second energy ratio as an edge frequency energy rate; the first energy ratio is the ratio of the energy of the side frequency of one time of the meshing frequency to the energy of one time of the meshing frequency; the second energy ratio is the ratio of the energy of the side frequency of twice the meshing frequency to the energy of twice the meshing frequency;
calculating the proportion of the sum of the first energy and the second energy in the energy of the whole frequency band according to the frequency component with the maximum energy in the velocity spectrum, the meshing frequency and the envelope spectrum to obtain the proportion of the side frequency energy rate; the first energy is the sum of the energy of one time of the meshing frequency and the energy of the side frequency of one time of the meshing frequency; the second energy is the sum of energy at twice the meshing frequency and energy at the side frequency at twice the meshing frequency.
5. A method of automatically diagnosing a gear fault in a gearbox according to claim 1 wherein said first set threshold is 0.4; the second set threshold is 2.8; the third set threshold is 0.5; the fourth setting threshold is 0.5.
6. An automatic diagnostic system for gear failure of a gearbox, comprising:
the data acquisition module is used for acquiring a vibration acceleration signal of a gear shaft in the target gear box and the meshing frequency of gears on the gear shaft;
the speed spectrum envelope spectrum determining module is used for determining a speed spectrum and an envelope spectrum of the gear shaft according to the vibration acceleration signal;
the first index determining module is used for determining a modulation frequency identifier according to the meshing frequency and the frequency component with the largest energy in the envelope spectrum;
the second index determining module is used for calculating an engagement frequency energy ratio, a side frequency energy ratio and a side frequency energy ratio according to the frequency component with the largest energy in the velocity spectrum, the engagement frequency and the envelope spectrum;
the third index determining module is used for calculating the acceleration kurtosis according to the vibration acceleration signal;
the fault diagnosis module is used for carrying out fault diagnosis on the target gearbox according to the modulation frequency identification, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result; the diagnosis result comprises a gear-free fault, a gear meshing fault, a gear local abrasion fault and a gear local broken tooth fault;
the fault diagnosis of the target gearbox is performed according to the modulation frequency identifier, the meshing frequency energy ratio, the side frequency energy rate ratio and the acceleration kurtosis to obtain a diagnosis result, and the fault diagnosis specifically includes:
if the target gearbox meets a first judgment condition, determining that no gear fails; the first judgment condition is that the engagement frequency energy ratio is less than or equal to a first set threshold;
if the target gearbox meets a second judgment condition, determining that a gear meshing failure fault exists; the second judgment condition is that the engagement frequency energy ratio is greater than a first set threshold and the acceleration kurtosis is less than or equal to a second set threshold;
if the target gearbox meets a third judgment condition, determining that a first compound fault exists; the first compound fault is a fault of gear meshing failure and bearing damage compound; the third judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, and the modulation frequency identification is 0;
if the target gearbox meets a fourth judgment condition, determining that a second compound fault exists, wherein the second compound fault is a fault of gear meshing failure and bearing loosening combination; the fourth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, and the side frequency energy ratio is less than or equal to a third set threshold; the gear mesh failure comprises the gear mesh failure, the first compound failure, and the second compound failure;
if the target gearbox meets a fifth judgment condition, determining that a gear local abrasion fault exists; the fifth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is less than or equal to a fourth set threshold;
if the target gearbox meets the sixth judgment condition, determining that a local gear breakage fault of the gear exists; the sixth judgment condition is that the engagement frequency energy ratio is greater than a first set threshold, the acceleration kurtosis is greater than a second set threshold, the modulation frequency identifier is 1, the side frequency energy ratio is greater than a third set threshold, and the side frequency energy ratio is greater than a fourth set threshold;
the automatic gearbox gear fault diagnosis system is used for realizing the automatic gearbox gear fault diagnosis method of any one of claims 1 to 5.
7. A gearbox gear fault automatic diagnostic system according to claim 6, characterized in that said data acquisition module specifically comprises:
the vibration data acquisition unit is used for acquiring a vibration acceleration signal of the gear shaft by adopting a vibration acceleration sensor; the vibration acceleration sensor is arranged at the bearing position of a gear shaft in the target gearbox;
the static parameter acquisition unit is used for acquiring the rotation frequency of the gear shaft and the number of gear teeth on the gear shaft;
and the meshing frequency calculation unit is used for calculating the meshing frequency of the gears on the corresponding gear shafts according to the rotating frequency of the gear shafts and the number of the gear teeth.
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