Gear meshing impact test extraction method

Abstract

The invention discloses a gear meshing impact test extraction method, and belongs to the technical field of gear transmission system testing. For the gear transmission system, firstly, tooth surface loads of all branches of the gear transmission system are measured by adopting a strain gauge bridge adhered to the tooth root of a driven wheel, then engagement impact signals of all the branches of the gear transmission system are separated and extracted by combining Hilbert-Huang transform, wavelet noise reduction and instantaneous frequency theories, and the advanced engagement occurrence position is judged; and thus, the system engagement impact is obtained. According to the method, analysis and research on test signals are carried out by means of Hilbert-Huang transform, wavelet noise reduction and an instantaneous frequency theory, gear teeth with meshing impact in the operation process can be accurately judged, and a basis is provided for real-time modification design and dynamic performance evaluation of a complex transmission system.

Description

Technical Field

[0001] The present invention relates to the technical field of gear transmission system testing, and specifically to a method for extracting gear meshing impact test. Background Art

[0002] In a gear transmission system, due to factors such as installation error, manufacturing error, and tooth load deformation, the gears will deviate from the theoretical meshing trajectory during the meshing process, resulting in meshing impact. Existing research mostly focuses on single pairs of gear pairs, but the actual transmission system contains multiple pairs of internal and external meshing gear pairs, there is a correlation between each branch, and the eccentric error and installation error of each gear are different, resulting in significant differences in the meshing impact position points and meshing impact forces of each internal and external gear pair in each meshing cycle. Therefore, it is unreasonable to simply divide the system into independent internal and external meshing pairs to analyze the influence of meshing impact on the load sharing and dynamic load characteristics of the transmission system.

[0003] Since the strain signals obtained in the experiment contain various signal components, the presence of noise and interference increases the difficulty of obtaining the meshing impact signal. It is necessary to use signal analysis and processing methods to obtain the required meshing impact test signal. Existing signal analysis and processing methods usually use Fourier analysis theory. Fourier transform is a pure frequency domain analysis method, and its positioning in the frequency domain is completely accurate, but the disadvantage is that it has no positioning resolution ability in the time domain and cannot provide the frequency domain properties of any local time period.

[0004] Meshing impact is a key factor determining the transmission quality of a gear system. It is of great significance to accurately determine the meshing impact in evaluating the transmission performance and gear modification. Therefore, it is necessary to propose a method for extracting gear meshing impact test that considers multiple internal and external meshing gears and uses a new signal processing method to accurately obtain the required meshing impact information. Summary of the Invention

[0005] The present invention aims to provide a method for extracting gear meshing impact test, which considers multiple internal and external meshing gears and uses a new signal processing method to separate and extract the measured tooth surface load, thereby obtaining accurate meshing impact information.

[0006] To achieve the above object, the design scheme of the present invention is as follows:

[0007] For a gear transmission system, first, the tooth surface loads of each branch of the gear transmission system are measured by using a strain gauge bridge pasted on the tooth root of the driven gear, and then, combined with the Hilbert-Huang transform, wavelet denoising, and instantaneous frequency theory, the meshing impact signals of each branch of the gear transmission system are separated and extracted, and the position where early meshing occurs is determined, so as to obtain the system meshing impact.

[0008] Further, the test method is as follows: First, a sensor is formed by using a strain gauge bridge measurement method. Strain gauges R1 and R2 are respectively pasted on the compressed side and the tensile side of the root of the driven wheel tooth, and form a bridge with external resistors R3 and R4. Then, a test and measurement platform for the gear transmission system is built, and the output signals of the sensor are measured under various transmission torque and rotational speed conditions.

[0009] Further, the steps for extracting the meshing signal are as follows:

[0010] Step 1: Demodulate the strain signal data sampled in the test by using the Hilbert-Huang transform, and obtain the default threshold by means of wavelet theory to remove the high-frequency clutter signals existing in the strain test signals.

[0011] Step 2: According to the meshing impact characteristics, the advance of the tooth tip meshing will cause changes in the original tooth root stress, resulting in a sudden change in the instantaneous frequency of the signal. By using the instantaneous frequency theory to analyze the time-domain waveform of the strain, the position of the abnormal frequency fluctuation point can be determined, and the position point and time point of the meshing impact generation can be judged. From the occurrence point of the meshing collision to the point where the relative speed is zero, the period is the energy consumption process of the meshing impact, that is, the action time of the meshing impact, and it is the process of the meshing impact causing the bearing deformation of the tooth surface. Thus, the required meshing impact information can be obtained.

[0012] Advantages of the present invention:

[0013] The strain gauge bridge pasted on the root of the internal gear ring has the functions of superimposing tensile and compressive stresses and temperature compensation; the measured tooth root stress is proportional to the tooth surface load, ensuring the linear relationship between the sensor measurement signal and the tooth surface load, and guaranteeing the measurement sensitivity and accuracy.

[0014] By means of the Hilbert-Huang transform, wavelet noise reduction and instantaneous frequency theory, the meshing impact signals of each branch of the planetary transmission system are successfully separated and extracted, and the tooth engaged with meshing impact during the operation can be accurately judged, providing a basis for real-time modification design and dynamic performance evaluation of complex transmission systems. Description of the Drawings

[0015] Figure 1 is the strain gauge bridge;

[0016] Figure 2 is the strain gauge pasting position;

[0017] Figure 3 is the meshing process of the planetary gear and the internal gear ring;

[0018] (a) is the meshing of the previous pair of teeth;

[0019] (b) is the meshing of the next pair of teeth;

[0020] Figure 4 is the output signal of the sensor;

[0021] Figure 5 is a test platform for planetary gear transmission system;

[0022] Figure 6 is the patch map of the internal gear ring test piece;

[0023] Figure 7 is the wavelet denoising of strain signal and determination of meshing impact signal (39.5 r / min); Specific implementation scheme

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Taking a 5 - planet gear transmission system as an example, the parameters of each component of the system are shown in Table 1. For the meshing pair of planetary gears and internal gear rings, the internal gear ring is the driven gear.

[0026] Table 1

[0027]

[0028] 1. The present invention uses a strain gauge bridge measurement method to form a sensor. As Figure 1 shown, strain gauges R 1 , R 2 are respectively pasted on the compression side and the tension side of the tooth root of the fixed non - rotating internal gear ring gear, and are combined with external resistors R 3 , R 4 to form a bridge. The long axis direction of the strain gauge is set at an angle of 60° with the tooth center line (as Figure 2 shown), and is tangent to the tooth root transition curve.

[0029] 2. Figure 3 shows the meshing process of the planetary gear and the internal gear ring. Among them, the tooth of the internal gear ring with the strain gauge is the current tooth. When the current tooth has not entered the meshing state while the previous pair of teeth is in the meshing state, the stress direction is that R1 is in tension and R2 is in compression at this time; when the current tooth enters the meshing state, R1 is in compression and R2 is in tension.

[0030] Furthermore, adjust the positive and negative polarities of the sensor output signal, with the signal being positive when R 1 is in tension and R 2 is in compression. When the top of the internal gear ring tooth of the previous pair of teeth meshes, the sensor outputs a negative signal; when the current tooth meshes, the sensor outputs a positive signal and the amplitude is the largest. As Figure 4As shown, the signal output by the sensor is proportional to the tooth root stress, and the tooth root stress is proportional to the tooth surface load of the tooth. The difference between the negative amplitude of the previous pair of teeth and the positive amplitude of the current tooth is used as a measure of the tooth surface load.

[0031] 3. Build a test platform for the planetary transmission system, as Figure 5 shown, measure the experimental data of the strain gauge under various working conditions. Figure 6 It is the patch diagram of the internal gear ring test piece.

[0032] 4. First, use Hilbert-Huang to demodulate the strain signal data sampled in the experiment. Since the acquired strain test signal contains various high-frequency clutter signals, the wavelet theory is used to obtain the default threshold to remove the high-frequency clutter signals. The obtained result diagram is as Figure 7 shown, (a) and (b) are respectively the strain signal of the tooth root stress and the strain signal after wavelet noise reduction processing of the strain gauge at a rotational speed of 39.5 r / min; (c) is the instantaneous frequency change of the signal in (b); (d) represents the meshing impact position point and the action time, etc.

[0033] Furthermore, by obtaining the instantaneous frequency of the strain signal after filtering and noise reduction, the abnormal frequency change of the strain signal waveform at any moment is determined. According to the meshing impact characteristics, the premature engagement of the tooth tip will cause a change in the original tooth root stress, resulting in a sudden change in the instantaneous frequency of the signal. When the tooth tip of the current tooth engages prematurely, the tooth root strain gauge R1 is compressed, causing a positive signal jump in the original negative signal; when the tooth tip of the next pair of gear pairs engages prematurely and impacts, it will cause the original positive signal in the strain gauge to turn into a negative signal. Combining the tooth root stress analysis, the collision point of the meshing impact can be obtained.

[0034] Furthermore, the section from the initial meshing impact collision point to the point where the meshing relative speed drops to zero is the tooth surface force deformation stage. This stage will cause a sharp increase in the original signal, and the increased part is the strain generated by the meshing impact.

[0035] Furthermore, the maximum strain wave peak value is the deformation caused by the normal meshing force after the tooth enters the correct meshing position, not caused by the meshing impact force. By comparing with the tooth root stress fluctuation amplitude and combining the normal meshing force amplitude of the internal meshing gear pair in the planetary transmission system, the magnitude of the meshing impact force can be further determined.

[0036] Due to the differences in the manufacturing and installation errors of each component, the meshing impact position points and the magnitudes of the meshing impact forces of different internal meshing pairs are also different. This situation is consistent with the meshing impact characteristics of the planetary transmission system under real working conditions, as shown in Table 2 specifically.

[0037] Table 2

[0038]

[0039] The series of detailed descriptions listed above are only specific descriptions of the feasible implementation manners of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation manners or modifications made without departing from the technical spirit of the present invention should be included within the protection scope of the present invention.

Claims

1. A gear meshing impact test extraction method, characterized in that: Firstly, the tooth surface load of each branch of the gear transmission system is measured by using a strain gauge bridge attached to the root of the driven wheel tooth. Then, the meshing impact signals of each branch of the gear transmission system are separated and extracted by combining Hilbert-Huang transform, wavelet denoising and instantaneous frequency theory, and the position where the early meshing occurs is determined, thereby obtaining the system meshing impact.

2. A gear meshing impact test extraction method according to claim 1, characterized in that: The test method is as follows: first, a strain gauge bridge measurement method is used to form a sensor, and strain gauges R1 and R2 are respectively attached to the compression side and tension side of the tooth root of the fixed inner ring gear, and form a bridge with external resistors R3 and R4. Then, a gear transmission system test platform is built to measure the sensor output signal under various torque and speed test conditions.

3. The gear meshing impact test extraction method according to claim 1, characterized in that: The meshing signal extraction steps are as follows: Step 1: Demodulate the strain signal data sampled by the test by using Hilbert-Huang transform, and use the wavelet theory to obtain the default threshold to remove the high-frequency clutter signal in the strain test signal; Step 2: According to the characteristics of meshing impact, early tooth top meshing will cause changes in the original tooth root stress, resulting in a sudden change in the instantaneous frequency of the signal. The instantaneous frequency theory is used to analyze the time domain waveform of the strain to determine the location of the abnormal frequency fluctuation point and the location and time point of the meshing impact. From the point of occurrence of the meshing collision to the point where the relative speed is zero, the energy consumption process of the meshing impact, that is, the action time of the meshing impact, is the process in which the meshing impact causes the tooth surface to produce load-bearing deformation. At this point, the required meshing impact information can be obtained.

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