Convenient, practical and high-precision method for measuring uniform load and dynamic load coefficients of planetary transmission system

Abstract

The invention provides a convenient, practical and high-precision method for measuring the uniform load and dynamic load coefficients of the planetary transmission system and a corresponding strain bridge sensor design method, and the method has the advantages of superposition of tension and compression stress, temperature compensation, avoidance of tedious calibration and the like. And a technical approach is provided for solving the actual measurement of the uniform load and dynamic load performance of the planetary transmission system.

Description

Technical Field

[0001] The present invention relates to the technical field of planetary drive system performance testing, and particularly relates to a method for measuring the load sharing and dynamic load coefficients of a planetary drive system. Background Art

[0002] Planetary drive systems are widely used in many industrial fields, and their load sharing performance and dynamic load performance are important indicators for measuring the system performance. Accurately measuring the load sharing and dynamic load performance of a planetary drive system is an important means to verify the configuration parameter design and load sharing optimization scheme of the planetary drive system, and is also an effective means to clarify the influence law of incentives such as errors. However, there are some problems in the existing methods for measuring the load sharing and dynamic load coefficients of planetary drive systems.

[0003] Poor sensitivity and accuracy: In some measurement methods, due to unreasonable sensor design or strain gauge pasting method, the sensitivity of the obtained signal is not high, and the measurement accuracy is difficult to meet the requirements.

[0004] Lack of coefficient test algorithms: Many documents do not give the specific calculation methods for the load sharing coefficient and dynamic load coefficient in the planetary drive system test, making the measurement results lack accurate and effective evaluation criteria.

[0005] Incorrect test stress points: Some measurement methods have misunderstandings about the angle of the position with the maximum tooth root stress, resulting in inaccurate test stress points and affecting the accuracy of the measurement results.

[0006] Therefore, it is necessary to propose a convenient, practical, and high-precision method for measuring the load sharing and dynamic load coefficients of a planetary drive system, which provides an important theoretical basis and technical means for accurately measuring the load sharing and dynamic load performance of the planetary drive system. Summary of the Invention

[0007] The present invention proposes a convenient, practical, and high-precision method for measuring the load sharing and dynamic load coefficients of a planetary drive system. This method uses a strain gauge bridge measurement method to form a sensor, and through reasonable sensor design and determination of corresponding calculation methods, the purpose is to achieve accurate measurement of the load sharing and dynamic load coefficients of the planetary drive system.

[0008] In order to achieve the above purpose, the technical invention steps adopted by the present invention are as follows:

[0009] (1) Sensor design step:

[0010] Preferably, a convenient, practical, and high-precision method for measuring the load sharing and dynamic load coefficients of a planetary drive system. The strain gauges R1 and R2 are respectively pasted on the compression side and the tension side of the tooth root of the fixed non-rotating internal gear ring gear, pasted on the gear end face, the long axis direction of the strain gauge forms a 60° angle with the tooth center line, and is tangent to the tooth root transition curve, and forms a bridge with the external resistors R3 and R4, where the strain gauges R1 and R2 are adjacent sides of the bridge.

[0011] (2) Step for determining measurement principle:

[0012] Preferably, a method for measuring the load sharing coefficient and dynamic load coefficient of a planetary transmission system that is convenient, practical, and has high precision. According to the fact that the output signal of the sensor is proportional to the tooth root stress, the tooth root stress is proportional to the tooth surface load, and the load sharing coefficient is related to the ratio of the transmitted torques of each branch, and the dynamic load coefficient is related to the ratio of the maximum dynamic load coefficient and the average dynamic load (static load), it is determined that the specific load magnitude does not need to be measured.

[0013] Specifically, a method for measuring the load sharing coefficient and dynamic load coefficient of a planetary transmission system that is convenient, practical, and has high precision. Based on the variation law of the tooth root stress during the meshing process of the planetary gear and the internal gear ring, the tooth of the internal gear ring with the strain gauge attached is the current tooth. When the current tooth has not entered meshing and the previous pair of teeth of the current tooth are in the meshing state, the previous pair of meshing teeth have already generated stress at the strain gauge attachment position of the current tooth. At this time, R1 is in tension and R2 is in compression, which are the main stresses at the tooth root of the current tooth. Subsequently, the current tooth enters meshing. At this time, R1 is in compression and R2 is in tension, and the stress direction is opposite to that when the previous pair of teeth are meshing, and the tooth root stress generated by the current tooth is greater and becomes the main stress. As the planetary gear and the internal gear ring further mesh, the previous pair of teeth disengage from meshing, and the next pair of teeth of the current tooth enter meshing. At this time, the tooth root stress generated by the current tooth is still the main stress. As the meshing continues, the current tooth disengages from meshing, and then the stress generated by the next pair of teeth at the strain gauge becomes the main stress.

[0014] For the meshing pair of the planetary gear and the internal gear ring, the internal gear ring gear is the driven gear, that is, during the meshing process, the tooth tip of the internal gear ring gear first enters meshing and exits meshing from the tooth root. The tooth root stress is larger when the tooth tip meshes and smaller when the tooth root meshes. At the same time, adjust the positive and negative polarities of the sensor output signal so that the signal is positive when R1 is in tension and R2 is in compression.

[0015] Thus, the variation of the tooth root stress and the positive and negative characteristics of the sensor output signal when the current tooth enters meshing, does not enter meshing, and disengages from meshing are determined. Among them, the sensor outputs a negative signal when the tooth tip of the internal gear ring gear of the previous pair of teeth meshes, and the sensor outputs a positive signal and the amplitude is the largest when the current tooth meshes. Considering that the strain signal (stress value) is proportional to the tooth surface load. Therefore, 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.

[0016] (3) Step for analyzing the output signal of the test sensor:

[0017] For the test planetary gear train containing multiple planetary gears, determine the characteristic that the output signal waveform of the strain gauge sensor presents multiple waveforms (one revolution of the planet carrier) as one cycle.

[0018] Specifically, a method for measuring the load sharing and dynamic load coefficients of a planetary transmission system that is convenient, practical, and highly accurate. Calculate the signal amplitude U representing the torque transmitted by planet gear m m as and take the average value of (U m , U 5+m , …, U 5(m-1)+m ) as the signal amplitude of the torque transmitted by planet gear m.

[0019] (4) Calculation steps for the load sharing and dynamic load coefficients of the planetary gear train test:

[0020] Calculate the load sharing coefficient according to the definition of the load sharing coefficient of the planetary gear train

[0021] Calculate the dynamic load coefficient according to the definition of the dynamic load coefficient of the planetary gear train

[0022] Preferably, a method for measuring the load sharing and dynamic load coefficients of a planetary transmission system that is convenient, practical, and highly accurate. Select multiple teeth along the circumferential direction of the internal gear ring and paste multiple groups of strain gauges to form multiple sensors, which are used to approximately measure the worst load sharing coefficient and dynamic load coefficient during the entire transmission process.

[0023] Advantages of the present invention:

[0024] (1) Improve sensitivity and temperature compensation: By pasting strain gauges R1 and R2 on the compression side and tension side of the tooth root respectively and forming adjacent sides of the bridge, the compressive stress and tensile stress signals can be superimposed, thereby improving the sensitivity of the sensor. At the same time, since the positions of R1 and R2 are close, when the temperature changes, the signals of the two strain gauges can cancel each other out, achieving temperature compensation.

[0025] (2) Ensure measurement accuracy: Since the tooth root stress is proportional to the tooth surface load and the bridge signal is linearly related to the tooth surface load, the sensor can accurately measure the tooth surface load, ensuring the measurement accuracy.

[0026] (3) No need for calibration: Considering that the load sharing characteristics and dynamic characteristics of the transmission system are relative proportional relationships of the tooth surface load rather than absolute values, the output voltage of the sensor bridge can represent the relative relationship of the tooth surface load. Therefore, there is no need to calibrate the sensor, avoiding the cumbersome work and possible errors during the calibration process.

[0027] (4) Improve measurement accuracy: Since the internal gear ring is fixed and does not rotate, the signal of the sensor can be directly led out through the signal wire without the need for indirect derivation methods such as slip rings or frequency modulation transmitters, thereby greatly improving the measurement accuracy.

[0028] (5) Overcoming the influence of zero drift: The output signal of the sensor is characterized by the relative difference between the positive and negative maximum values. During the measurement process, due to factors such as environmental noise, zero drift of the signal is almost inevitable. However, the relative difference utilized in the present invention is independent of zero drift, thus overcoming the influence of zero drift. Description of the Drawings

[0029] Figure 1 Strain gauge bridge

[0030] Figure 2 Pasting position of strain gauges on the tooth root of the internal gear ring

[0031] Figure 3 Meshing process of the planet gear and the internal gear ring

[0032] (a) Meshing of the previous pair of teeth

[0033] (b) Meshing of the current tooth

[0034] Figure 4 Output signal of the sensor

[0035] Figure 5 Prediction of the output signal of the planetary transmission system sensor

[0036] Figure 6 Pasting diagram of the L-shaped flexible internal gear ring test piece

[0037] Figure 7 Schematic diagram of the test platform of the L-shaped flexible internal gear ring planetary gear train

[0038] Figure 8 Schematic diagram of the pasting position on the upper end face of the internal gear ring tooth

[0039] Figure 9 Schematic diagram of the pasting position on the back of the internal gear ring rim

[0040] Figure 10 Schematic diagram of the pasting position of the internal gear ring along the tooth width direction

[0041] (a) Position in the tooth width direction

[0042] (b) Position in the tooth profile direction

[0043] Figure 11 Schematic diagram of the pasting position on the planet carrier

[0044] (a) Overview of the overall pasting position

[0045] (b) Dimensions of the local pasting position

[0046] Figure 12 Comparison of the output signals of four pasting methods

[0047] (a) SMT method 1;

[0048] (b) SMT method 2;

[0049] (c) SMT method 3;

[0050] (d) SMT method 4;

[0051] Figure 13 Output signal of strain sensor under working condition 1;

[0052] (a) Signal of strain gauge 1;

[0053] (b) Signal of strain gauge 2;

[0054] (c) Signal of strain gauge 3;

[0055] (d) Signal of strain gauge 4;

[0056] (e) Signal of strain gauge 5;

[0057] Figure 14 Output signal of strain sensor under working condition 8;

[0058] (a) Signal of strain gauge 1;

[0059] (b) Signal of strain gauge 2;

[0060] (c) Signal of strain gauge 3;

[0061] (d) Signal of strain gauge 4;

[0062] (e) Signal of strain gauge 5; Specific implementation

[0063] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0064] The embodiment model provided by the present invention is a certain planetary transmission system, and the specific structural dimensions are as shown in Table 1 below

[0065] Table 1 Parameters of components of planetary transmission system

[0066]

[0067] (1) Sensor design steps:

[0068] A sensor is composed by using the strain gauge bridge measurement method as Figure 1As shown in the figure, strain gauges R1 and R2 are respectively pasted on the compression side and the tension side of the tooth root of the fixed non-rotating internal gear ring gear, pasted on the gear end face, and the long axis direction of the strain gauge forms an angle of 60° with the tooth center line as Figure 2 shown, and is tangent to the tooth root transition curve, and forms a bridge with external resistors R3 and R4, where strain gauges R1 and R2 are adjacent sides of the bridge.

[0069] (2) Steps to determine the measurement principle:

[0070] According to the fact that the output signal of the sensor is proportional to the tooth root stress, the tooth root stress is proportional to the tooth surface load, and the load sharing coefficient is related to the ratio of the transmitted torque of each branch, and the dynamic load coefficient is related to the ratio of the maximum dynamic load coefficient and the average dynamic (static) load, it is determined that there is no need to measure the specific load magnitude.

[0071] Based on the change law of the tooth root stress during the meshing process of the planet gear and the internal gear ring as Figure 3 shown, the tooth of the internal gear ring with the strain gauge pasted is the current tooth. When the current tooth has not entered meshing and the previous pair of teeth of the current tooth are already in the meshing state ( Figure 3 (a)), the previous pair of meshing teeth have already generated stress at the strain gauge pasting position of the current tooth. At this time, R1 is in tension and R2 is in compression, which are the main stresses of the current tooth root. Subsequently, the current tooth enters meshing. At this time, R1 is in compression and R2 is in tension, and the stress direction is opposite to that when the previous pair of teeth are meshing, and the tooth root stress generated by the current tooth is greater and becomes the main stress ( Figure 3 (b)). As the planet gear and the internal gear ring further mesh, the previous pair of teeth disengage from meshing, and the next pair of teeth of the current tooth enter meshing. At this time, the tooth root stress generated by the current tooth is still the main stress. As the meshing continues, the current tooth disengages from meshing, and the stress generated by the next pair of teeth at the strain gauge becomes the main stress.

[0072] For the meshing pair of the planet gear and the internal gear ring, the internal gear ring gear is the driven wheel, that is, during the meshing process, the tooth tip of the internal gear ring gear enters meshing first and exits from the tooth root. And the tooth root stress is larger when the tooth tip meshes and smaller when the tooth root meshes. At the same time, adjust the positive and negative polarities of the sensor output signal so that the signal is positive when R1 is in tension and R2 is in compression.

[0073] So far, the change of the tooth root stress and the positive and negative characteristics of the sensor output signal when the current tooth enters meshing, does not enter meshing, and disengages from meshing have been determined. Among them, when the tooth tip of the internal gear ring of the previous pair of teeth meshes, the sensor outputs a negative signal, and when the current tooth meshes, the sensor outputs a positive signal and the amplitude is the largest. Considering that the strain signal (stress value) is proportional to the tooth surface load, as Figure 4 shown. Therefore, 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.

[0074] (3) Steps to analyze the output signal of the test sensor:

[0075] For the test planetary gear train with five planet gears, the characteristic that the output signal waveform of the strain gauge sensor presents five waveforms (one revolution of the planet carrier) as a period is determined as follows Figure 5 shown;

[0076] Calculate the signal amplitude U representing the torque transmitted by planet gear m m as and take the average value of (U m , U 5+m , …, U 5(m-1)+m ) as the signal amplitude of the torque transmitted by planet gear m.

[0077] (4) Calculation steps for the load sharing coefficient and dynamic load coefficient of the planetary gear train test:

[0078] According to the definition of the load sharing coefficient of the planetary gear train, the load sharing coefficient is obtained

[0079] According to the definition of the dynamic load coefficient of the planetary gear train, the dynamic load coefficient is obtained

[0080] Select multiple teeth along the circumferential direction of the internal gear ring and paste multiple groups of strain gauges to form multiple sensors, which are used to approximately measure the worst load sharing coefficient and dynamic load coefficient during the entire transmission process.

[0081] (5) Comparison and verification of test measurement results:

[0082] In order to verify the rationality of the measurement method of the present invention, four strain gauge pasting methods are designed for comparison, Figure 6 is the strain gauge pasting diagram of the L-shaped flexible internal gear ring test piece in reality, Figure 7 is the schematic diagram of the test platform of the L-shaped flexible internal gear ring planetary gear train.

[0083] The method adopted by the present invention is to paste strain gauges at the upper end face position of the teeth of the internal gear ring (only the positions of strain gauges R1 and R2 are shown) as follows Figure 8 shown;

[0084] The second strain gauge pasting method is to paste strain gauges on the back of the rim of the internal gear ring as follows Figure 9 shown;

[0085] The third strain gauge pasting method is to paste strain gauges at the position near the tooth root along the tooth width direction of the teeth of the internal gear ring as follows Figure 10 shown;

[0086] The fourth strain gauge pasting method is to paste strain gauges on the planet carrier as follows Figure 11 shown.

[0087] (6) Comparative analysis of test signals:

[0088] The output signals of the sensors in four kinds of patch methods under the same working conditions were obtained through measurement. The comparison results are as Figure 12 shown. Among them, only the signal waveform measured by the first patch method (that is, the method of pasting strain gauges at the upper end face position of the teeth of the internal gear ring adopted in the present invention) has good regularity, and the signal waveform resolution that can clearly characterize the magnitude of the meshing force is high, meeting the test requirements. While the basic shapes of the signals obtained by the second patch method are the same, and the magnitude of the meshing force cannot be distinguished; there are more problems of high-frequency interference in the third and fourth patch methods, and it is difficult to distinguish the required signals. This further verifies the accuracy and rationality of the test method of the present invention.

[0089] (7) Comparison of measurement results under different working conditions:

[0090] To accurately obtain the load sharing and dynamic load performance of the planetary transmission system after adopting the L-shaped flexible internal gear ring, a variety of test conditions for transmitting torque and speed are designed as shown in Table 2 below. At least 20 tests and data samplings are carried out under each test condition, and it is necessary to ensure that the torque and speed of each test condition are kept as consistent as possible. At the same time, the signal sampling frequency and sampling time are reasonably adjusted according to the change of the speed.

[0091] Table 2 Design of test torque and speed

[0092]

[0093] It is known from the comparison of the measurement results of multiple groups of tests that at the same rotational speed, the output data of the strain gauge increases linearly with the increase of the torque. At the same torque, the data output by the strain gauge increases with the increase of the speed, which is due to the dynamic response of the system, but the increase is limited. In addition, for the need to obtain the dynamic load coefficient of the system, a very low input speed of 39.5 r / min is used to simulate the static working condition. Figure 13 、 Figure 14 are the output signals of the strain sensors in working condition 1 and working condition 8 respectively.

[0094] After observing and analyzing the output signals of each strain gauge, the signal stability and accuracy of strain gauge 1 are more prominent. Therefore, the output signal of strain gauge 1 is used as the standard for analyzing the load sharing coefficient and dynamic load coefficient of the planetary transmission system. The output test data of the strain gauge in the first five cycles of each planetary gear are selected as the analysis samples. According to the definitions of the load sharing coefficient and the dynamic load coefficient, the strain test results under two working conditions are given in Table 3 and Table 4. Then, according to the load sharing and dynamic load formula in step (4), dividing the strain of each planetary gear in Table 3 by the mean value of the strain can calculate the corresponding load sharing coefficient of the L-shaped flexible internal gear ring planetary transmission system, as shown in Table 5. Dividing the strain value obtained in working condition 8 by the strain value in working condition 1, the dynamic load coefficient of the planetary transmission system is finally obtained as shown in Table 6.

[0095] Table 3 Strain Test Data of Each Planet Gear (Operating Condition 1)

[0096]

[0097] Table 4 Strain Test Data of Each Planet Gear (Operating Condition 8)

[0098]

[0099] Table 5 Load Sharing Coefficient Data

[0100]

[0101] Table 6 Dynamic Load Coefficient Data

[0102]

[0103] As mentioned above, it is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the technical field, within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be within the protection scope of the present invention.

Claims

1. A method for measuring the load sharing and dynamic load coefficients of a planetary transmission system, which is convenient, practical, and has high precision, is characterized in that, Including the following steps: (1) Sensor design step: Paste strain gauges R1 and R2 on the compression side and the tension side of the tooth root of the fixed non-rotating internal gear ring respectively, paste them on the gear end face, the long axis direction of the strain gauge forms a 60° angle with the tooth center line, and is tangent to the tooth root transition curve, and form a bridge with external resistors R3 and R4, where strain gauges R1 and R2 are adjacent sides of the bridge; (2) Measurement principle determination step: Based on the fact that the sensor output signal is proportional to the tooth root stress, the tooth root stress is proportional to the tooth surface load, and the load sharing coefficient is related to the ratio of the transmitted torque of each branch, and the dynamic load coefficient is related to the ratio of the maximum dynamic load coefficient and the average dynamic load (static load), it is determined that there is no need to measure the specific load magnitude; According to the change law of the tooth root stress during the meshing process of the planet gear and the internal gear ring, determine the change of the tooth root stress and the positive and negative characteristics of the sensor output signal when the current tooth enters meshing, does not enter meshing, and disengages from meshing. Among them, when the tooth tip of the internal gear ring gear 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, and 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; (3) Test sensor output signal analysis step: For the test planetary gear train containing multiple planet gears, determine the characteristic that the output signal waveform of the strain gauge sensor presents multiple waveforms (one revolution of the planet carrier) as a cycle; Calculate the signal amplitude U representing the magnitude of the torque transmitted by planet gear m m For and take the average value of (U m , U 5+m , …, U 5(m-1)+m ) as the signal amplitude of the magnitude of the torque transmitted by planet gear m; (4) Planetary gear train test load sharing coefficient and dynamic load coefficient calculation step: Calculate the load sharing coefficient according to the definition of the load sharing coefficient of the planetary gear train Calculate the dynamic load factor according to the definition of the dynamic load factor of the planetary gear train Select multiple teeth along the circumference of the internal gear ring to paste multiple groups of strain gauges to form multiple sensors, which are used to approximately measure the worst load sharing coefficient and dynamic load coefficient during the entire transmission process.

2. The measurement method according to claim 1, characterized in that, The test planetary gear train contains five planet gears.

3. The measurement method according to claim 1, characterized in that, In the sensor design step, according to the ISO standard, the maximum tooth root stress of the internal gear ring is located at 60° of the tooth root transition curve.

4. The measurement method according to claim 1, characterized in that, In the calculation steps of the load sharing coefficient and the dynamic load coefficient of the planetary gear train, the amplitude U of the meshing tooth surface load signal of the planetary gear train under the working speed and load conditions dm and the amplitude U of the meshing tooth surface load signal between the same planetary gear and the internal gear ring of the planetary gear train under the quasi-static (extremely low speed) and the same load conditions sm are calculated according to the corresponding formulas, where the quasi-static means simulating the static working condition at an extremely low speed.

5. The measuring method according to claim 1, characterized in that, In the step of reflecting the advantages of the measurement method, temperature compensation means that when the temperature changes, the signals of the two strain gauges can cancel each other out.

6. The measurement method according to claim 1, characterized in that In the step of comparing and verifying the test measurement results, by comparing the sensor output signals of multiple patch methods, it is determined that there are problems such as the same basic signal shape and inability to distinguish the magnitude of the meshing force or extremely many high-frequency interferences and difficulty in distinguishing the required signals in the other three patch methods.

Images