Compressor pump body friction pair acceleration factor determination method based on accelerated wear model

Abstract

The invention provides a method for determining an acceleration factor of a friction pair of a compressor pump body based on an accelerated wear model. The method comprises the following steps: S1, collecting rated working conditions and structural parameters of a compressor; s2, determining a first acceleration working condition and a second acceleration working condition, and respectively determining suction pressure, exhaust pressure and rotation frequency of the first acceleration working condition and the second acceleration working condition; s3, a calculation model of the angle theta di of the cylinder compression cavity reaching the exhaust pressure is constructed, and a compression index m is solved; s4, the angles of the air cylinder compression cavity reaching the exhaust pressure under the first acceleration working condition and the second acceleration working condition are calculated correspondingly; s5, constructing a compressor pump body friction pair accelerated wear model and calculating an acceleration index kappa; and S6, based on the rated working condition and the experimental acceleration working condition, the accelerated wear model determined in the S5 is used for calculating the compressor pump body friction pair acceleration factor. According to the method, a large number of experimental samples are not needed, the calculation process is faster and more accurate, and the determined acceleration factor can be applied in multiple scenes.

Description

Technical Field

[0001] The invention relates to the field of compressor pump body reliability acceleration experiment, and in particular to a method for determining an acceleration factor of a compressor pump body friction pair based on an accelerated wear model. Background Art

[0002] One failure mode of compressor products is the wear failure of the friction pair of the pump body, and its wear life needs to be verified. During the product development process, the wear life of the product is generally verified through reliability experiments, but due to the problem of long experimental cycles, it is often necessary to carry out reliability acceleration experiments to improve verification efficiency.

[0003] The key to conducting reliability acceleration experiments is to establish an acceleration model and calculate the acceleration factor based on the failure time results under multiple high stress levels to evaluate the failure time under low stress levels. The current method of calculating the acceleration factor has two main problems. First, the required experimental sample size is too large. Generally, experiments need to be carried out under at least 3 stress levels, with at least 4 samples at each stress level, so at least 12 samples are required; second, the acceleration model is based on experimental data fitting and lacks a mechanistic explanation, which limits the applicability of the acceleration factor.

[0004] Therefore, there is an urgent need to provide a new method for determining the acceleration factor of the compressor pump body friction pair in order to solve the problems of the existing technology such as the large number of experiments and limited applicability. Summary of the invention

[0005] In order to address the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model, which can directly determine the acceleration factor of the compressor pump body friction pair through the mechanism model by determining the relevant fitting parameters. It does not require a large number of experimental samples during calculation, and the calculation process is faster and more accurate. At the same time, the compression index is determined by simulation analysis, and the acceleration index is determined by conducting wear experiments. Finally, the accurate acceleration factor can be applied in multiple scenarios.

[0006] Specifically, the present invention provides a method for determining the acceleration factor of a compressor pump body friction pair based on an accelerated wear model, which comprises the following steps:

[0007] S1. Collect the rated operating conditions and structural parameters of the compressor, wherein the rated operating conditions and structural parameters of the compressor include: rated operating suction pressure, rated operating exhaust pressure, rated operating rotation frequency, cylinder inner radius, roller sleeve outer radius, cylinder depth, and the angle between the lower edge of the suction port and the center line of the blade;

[0008] S2, determining a first acceleration operating condition and a second acceleration operating condition, and determining the intake pressure, exhaust pressure and rotation frequency of the first acceleration operating condition and the second acceleration operating condition respectively;

[0009] S3, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model and solving the compression index m specifically includes the following sub-steps:

[0010] S31, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model is:

[0011]

[0012] In the formula,

[0013]

[0014] in, is the suction pressure in the i-th working condition, is the exhaust pressure of the i-th working condition, R is the inner radius of the cylinder, r is the outer radius of the roller sleeve, H is the cylinder depth, β is the angle between the lower edge of the suction port and the center line of the blade, and m is the compression index;

[0015] S32. The calculation formula for constructing the compression index m is as follows:

[0016]

[0017] S33, performing simulation analysis to obtain the angle at which the cylinder compression chamber reaches the exhaust pressure and bringing it into the calculation formula of step S31 to obtain the value of the compression index m;

[0018] S4, using the calculation model in step S3, respectively calculate the angle θ at which the cylinder compression chamber reaches the exhaust pressure under the first acceleration condition and the second acceleration condition. d 1 and θ d 2 ;

[0019] S5, constructing a compressor pump body friction pair accelerated wear model and calculating the acceleration index κ, specifically including the following sub-steps:

[0020] S51. Construct the accelerated wear model of the compressor pump body friction pair as follows:

[0021]

[0022] Among them, F i 、F j are the maximum gas forces on the friction pair under the i-th and j-th working conditions, respectively, n i 、n j are the rotation frequencies of the compressor pump body under the i-th and j-th working conditions, respectively, and κ is the acceleration index;

[0023] S52, conducting a wear experiment to determine the acceleration index κ;

[0024] S6. Based on the parameters of the rated operating condition and the experimental accelerated operating condition, the compressor pump body friction pair accelerated wear model determined in step S5 is used to calculate the compressor pump body friction pair acceleration factor.

[0025] Preferably, the maximum gas force F exerted on the friction pair under condition i in step S51 is i The calculation formula is:

[0026]

[0027] Among them, P max i is the maximum pressure of the cylinder compression chamber under condition i, and b is the fitting parameter.

[0028] Preferably, the maximum pressure P of the cylinder compression chamber under condition i max i The calculation formula is:

[0029]

[0030] Preferably, the value of the compression index m is 1.6, the value of b is 0.18, and the value of the acceleration index κ is 9.67.

[0031] Preferably, in step S6, the compressor pump body friction pair acceleration factor A is calculated. PRE The specific calculation formula is:

[0032]

[0033] Among them, F 实 、F 额 are the maximum gas forces on the friction pair under experimental acceleration conditions and rated conditions, n 实 、n 额 They are the rotation frequencies of the compressor pump body under experimental acceleration conditions and rated conditions respectively.

[0034] Preferably, in step S2, the intake pressure of the first acceleration condition is the minimum limit value, and the intake pressure of the second acceleration condition is 1.05-1.1 times the intake pressure of the first acceleration condition;

[0035] The operating frequency of the second acceleration condition is the maximum limit value, and the operating frequency of the first acceleration condition is 0.75-0.8 times the operating frequency of the second acceleration condition;

[0036] The first acceleration condition exhaust pressure and the first acceleration condition exhaust pressure both take maximum limit values.

[0037] Preferably, step S52 specifically includes the following sub-steps:

[0038] S521, carrying out a compressor wear test under a first acceleration condition and a second acceleration condition respectively, selecting at least three samples for each acceleration condition, stopping the test when any performance of the compressor decays by more than 5%, and testing the wear amount of the friction pair of each sample after the test is completed;

[0039] S522, calculating the pseudo wear life of the friction pairs of each sample;

[0040] S523, respectively determining the wear life distribution of the friction pair under two acceleration conditions;

[0041] S524. Determine the acceleration index κ based on the wear life distribution of the friction pair under two acceleration conditions. The calculation formula is as follows:

[0042] Ln(n i t i )=Ln(C)-κLn(F i )

[0043] Among them, t i F is the time required for the friction pair to reach the expected wear state under the current working conditions. i is the maximum gas force on the friction pair under working condition i, and Ln(C) is the intercept.

[0044] Preferably, in step S522, the maximum wear amount of the friction pair among the multiple samples is selected as the reference wear amount. Based on the assumption that the wear volume in the stable wear stage is approximately linearly accumulated, the time for each friction pair of each experimental sample to reach the reference wear volume is calculated. As the pseudo failure life of the friction pair of each sample;

[0045] In step S523, based on the pseudo failure life of each sample, the maximum likelihood estimation method is used to estimate the life distribution of the sample under two acceleration conditions, that is, to determine the shape parameter and scale parameter of the Weibull distribution.

[0046] Preferably, in step S524, when the friction pair reaches the same wear state under multiple working conditions obtained by the accelerated wear model, there are:

[0047] (F 1 ) κ ×n×t0=(F 2 ) κ ×n′×t ALT =C

[0048] For the expression (F i ) κ ×n i ×t i =C Taking the logarithm of both sides we get:

[0049] Ln(ni ti)=Ln(C)-κLn(F i ).

[0050] Preferably, in step S5, the intake pressure, exhaust pressure and rotation frequency under the experimental acceleration condition are all obtained through experiments.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The present invention provides a method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model, which can directly calculate the compressor pump body friction pair acceleration factor through a calculation formula, and the acceleration index is obtained through simulation analysis. It does not require a large number of experimental samples, and the calculation process is faster and more accurate. In addition, the calculation formula of the compressor pump body friction pair acceleration factor takes into account the mechanism influence, and the determined acceleration factor can be applied in multiple scenarios.

[0053] (2) On the one hand, the present invention determines the value of the compression index m based on simulation analysis. Through verification, it can be seen that the starting exhaust angle calculated by the calculation model of the angle at which the cylinder compression chamber reaches the exhaust pressure is very close to the starting exhaust angle obtained by simulation, with almost no error, and can be accurately used in subsequent calculation processes. On the other hand, by carrying out wear experiments to determine the acceleration index κ, the accuracy of the accelerated wear model is guaranteed, thereby ensuring the accuracy of the acceleration factor value. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a flow chart of a method for determining acceleration factor of a compressor pump friction pair based on an accelerated wear model of the present invention;

[0055] Figure 2 A simulation model of the compressor working chamber of the present invention;

[0056] Figure 3 A schematic diagram of the grid division of the compressor working chamber of the present invention;

[0057] Figure 4a-4e It is a schematic diagram of the simulation of the working process of the compressor of the present invention;

[0058] Figure 5 This is a schematic diagram of the air pressure change curve output by the simulation;

[0059] Figure 6 To extract the schematic diagram of the compression chamber pressure variation curve within a single cycle;

[0060] Figure 7 A schematic diagram of an angle curve of exhaust pressure under the first acceleration condition is obtained for simulation;

[0061] Figure 8Schematic diagram of the angle curve of the exhaust pressure under the second acceleration condition obtained for simulation. DETAILED DESCRIPTION

[0062] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0063] Specifically, the present invention provides a method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model, such as Figure 1 As shown, it includes the following steps:

[0064] S1. Collect the rated operating conditions and structural parameters of the compressor, wherein the rated operating conditions and structural parameters of the compressor include: rated operating suction pressure, rated operating exhaust pressure, rated operating rotation frequency, cylinder inner radius, roller sleeve outer radius, cylinder depth, and the angle between the lower edge of the suction port and the center line of the blade.

[0065] S2. Determine a first acceleration operating condition and a second acceleration operating condition, and respectively determine the intake pressure, exhaust pressure, and rotation frequency of the first acceleration operating condition and the second acceleration operating condition.

[0066] The parameters of the acceleration condition are generally between the rated condition and the restricted condition. In a specific embodiment, the intake pressure of the first acceleration condition is the minimum limit value, and the intake pressure of the second acceleration condition is slightly larger than that of the first acceleration condition, generally 5%-10% larger, that is, 1.05-1.1 times the intake pressure of the first acceleration condition. The operating frequency of the second acceleration condition is the maximum limit value, and the operating frequency of the first acceleration condition is slightly lower than that of the second acceleration condition, generally reduced by 20% to 25%, that is, 0.75-0.8 times the operating frequency of the second acceleration condition. The exhaust pressure of the two acceleration conditions is in accordance with the restricted use conditions / overload use conditions, and the exhaust pressure takes the maximum limit value.

[0067] S3, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model and solving the compression index m specifically includes the following sub-steps:

[0068] S31, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model is:

[0069]

[0070] In the formula,

[0071]

[0072] in, is the suction pressure in the i-th working condition, is the exhaust pressure of the i-th working condition, R is the inner radius of the cylinder, r is the outer radius of the roller sleeve, H is the cylinder depth, β is the angle between the lower edge of the suction port and the center line of the blade, and m is the compression index. In a specific embodiment, the angle θ at which the cylinder compression chamber reaches the exhaust pressure under different working conditions can be solved based on the above formula. d i , which can ensure the accuracy of the calculation results and greatly reduce the workload.

[0073] S32. The calculation formula for constructing the compression index m is as follows:

[0074]

[0075] S33, performing simulation analysis to obtain the angle at which the cylinder compression chamber reaches the exhaust pressure and bringing it into the calculation formula of step S31 to obtain the value of the compression index m.

[0076] The specific simulation process is as follows:

[0077] Fluid simulation uses Simerics PumpLinx software to establish a CAD model of the structural fluid based on the structural dimensions and working principle. Figure 2 shown.

[0078] First, the fluid area and fluid boundary are divided according to the fluid inlet, fluid outlet, exhaust valve port, rotor, cylinder inner wall and other parts. The CAD model is divided into different blocks according to different types, and the fluid and dynamic grid settings are performed for different types of fluids and their boundary areas, such as Figure 3 shown.

[0079] The working parameters are set in the model, including suction pressure, exhaust pressure, rotation speed, gas parameters, gap, etc. After the working parameters are set, the fluid solution parameters are set. Since the gas flow in each gap and the compression chamber is turbulent during the rotation process, a two-parameter turbulence equation needs to be introduced in the simulation, and the difference format is a first-order upwind format.

[0080] After all parameters are set, the solution can be performed. The solution process is consistent with the actual working process. In one cycle, it rotates around the inner wall once and completes one compression and exhaust. The whole process is as follows: Figure 4a-4e shown.

[0081] The pressure change curve of the simulation output is as follows: Figure 5 As shown in the figure, the pressure variation curve of the compression chamber in a single cycle is extracted as follows: Figure 6 Based on the above curve, the exhaust start angle θ can be determined d, that is, the angle when the pressure reaches the specified exhaust pressure, the exhaust start angle is substituted into the formula for solving the compression index m, thereby solving for the value of the compression index m. In one embodiment, the final solved m value is 1.6, which is also the optimal value in a specific application.

[0082] S4, using the calculation model in step S3, respectively calculate the angle θ at which the cylinder compression chamber reaches the exhaust pressure under the first acceleration condition and the second acceleration condition. d 1 and θ d 2 .

[0083] S5, constructing a compressor pump body friction pair accelerated wear model and calculating the acceleration index κ, specifically including the following sub-steps:

[0084] S51. Construct the accelerated wear model of the compressor pump body friction pair as follows:

[0085]

[0086] Among them, F i 、F j are the maximum gas forces on the friction pair under the i-th and j-th working conditions, respectively, n i 、n j are the rotation frequencies of the compressor pump body under the i-th working condition and the j-th working condition respectively, and κ is the acceleration index.

[0087] The maximum gas force F acting on the friction pair under condition i i The calculation formula is:

[0088]

[0089] Among them, P max i is the maximum pressure of the cylinder compression chamber under condition i, b is a fitting parameter, and in one embodiment, the value of b is 0.18.

[0090] Among them, the maximum pressure of the cylinder compression chamber under condition i is P max i The calculation formula is:

[0091]

[0092] The construction process of the accelerated wear model is:

[0093] The general relationship between the amount of wear on the friction surface that undergoes adhesive wear per unit sliding distance and the contact pressure is:

[0094] I=KP κ

[0095] Where K is the wear coefficient, which is related to structural parameters and working conditions such as material hardness, surface roughness, lubrication state, etc. P is the surface contact pressure, which is determined by external load conditions; κ is related to the part structure and is generally determined through experiments.

[0096] Taking the same total wear amount as the equivalent basis for the accelerated test, we have:

[0097]

[0098] In the formula, K ALT , K0 represent the wear coefficients under accelerated working condition and normal working condition respectively; They represent the unit contact pressure under acceleration and normal conditions respectively; S represents the relative sliding displacement of the friction pair after one rotation of the pump body; t ALT , t0 represent the time required to achieve the same amount of wear under accelerated conditions and normal conditions respectively.

[0099] In the accelerated test, by constraining the range of pressure and temperature, the wear mechanism of the friction pair is ensured to be similar to the lubrication state. It can be considered that K ALT =K0, at the same time, S is only related to the structural size and has nothing to do with the working conditions, then:

[0100]

[0101] Right now:

[0102]

[0103] S52, conducting a wear experiment to determine the acceleration index κ, specifically including the following sub-steps:

[0104] S521. Carry out compressor wear experiments under the first acceleration condition and the second acceleration condition respectively. Select at least 3 samples for each acceleration condition. Stop the experiment when any performance of the compressor shows attenuation of more than 5%. After the experiment is completed, test the wear amount of the friction pair of each sample.

[0105] S522, calculate the pseudo wear life of the friction pair of each sample: select the maximum wear amount of the friction pair among multiple samples as the reference wear amount Based on the assumption that the wear volume in the stable wear stage is approximately linearly accumulated, the time for each friction pair of each experimental sample to reach the reference wear volume is calculated. As the pseudo failure life of the friction pair of each sample.

[0106] S523. Determine the wear life distribution of the friction pair under two acceleration conditions respectively: Based on the pseudo failure life of each sample, use the maximum likelihood estimation method to estimate the life distribution of the sample under two acceleration conditions, that is, determine the shape parameter and scale parameter of the Weibull distribution.

[0107] S524. Determine the acceleration index κ based on the characteristic life under two acceleration conditions. When the friction pair reaches the same wear state under multiple conditions, the following is obtained from the accelerated wear model:

[0108] (F 1 ) κ ×n×t0=(F 2 ) κ ×n′×t ALT =C.

[0109] For the expression (F i ) κ ×n i ×t i =C Taking the logarithm of both sides we get:

[0110] Ln(n i t i )=Ln(C)-κLn(F i ).

[0111] Among them, t i It is the time required for the friction pair to reach the expected wear state under the current working conditions.

[0112] In one embodiment, the calculated acceleration index κ=9.67, which is also the optimal value in a specific application.

[0113] S6. Based on the parameters of the rated operating condition and the experimental accelerated operating condition, the compressor pump body friction pair accelerated wear model determined in step S5 is used to calculate the compressor pump body friction pair acceleration factor.

[0114] In step S6, the compressor pump body friction pair acceleration factor A is calculated. PRE The specific calculation formula is:

[0115]

[0116] Among them, F 实 、F 额 are the maximum gas forces on the friction pair under experimental acceleration conditions and rated conditions, n 实 、n 额 They are the rotation frequencies of the compressor pump body under experimental acceleration conditions and rated conditions respectively.

[0117] In a specific embodiment, the intake pressure, exhaust pressure and rotation frequency under experimental acceleration conditions are obtained through experiments. Specific embodiment 1

[0119] S1. Collect the rated operating conditions and structural information of the compressor as shown in Table 1.

[0120] Table 1

[0121]

[0122] S2. Determine two acceleration conditions and the parameters of the two acceleration conditions as shown in Table 2.

[0123] Table 2

[0124] Condition No. Inspiratory pressure Exhaust pressure Frequency (Hz) 1 0.75 4.8 85 2 0.8 4.8 110

[0125] S3, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model and solving the compression index m specifically includes the following sub-steps:

[0126] S31, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The computational model.

[0127] S32, substituting the exhaust start angle obtained by simulation into the formula for solving the compression process index m:

[0128]

[0129] The compression index m was found to be 1.6.

[0130] The simulation data is shown in Table 3:

[0131]

[0132] The angle curve diagrams of the scheduling pressure of the two working conditions obtained by simulation are as follows: Figure 7 and Figure 8 As shown, Figure 7 A schematic diagram of an angle curve of exhaust pressure under the first acceleration condition is obtained for simulation; Figure 8 Schematic diagram of the angle curve of the exhaust pressure under the second acceleration condition obtained for simulation.

[0133] S4, using the calculation model in step S3, respectively calculate the angle θ at which the cylinder compression chamber reaches the exhaust pressure under the first acceleration condition and the second acceleration condition. d 1 and θ d 2 The theoretical values ​​of the exhaust angles calculated are shown in Table 4.

[0134] Table 4 Theoretical values ​​of exhaust angle

[0135]

[0136] It can be seen from the table that the angle θ at which the cylinder compression chamber reaches the exhaust pressure d iThe starting exhaust angle calculated by the calculation model is very close to the starting exhaust angle obtained by simulation, with almost no error, and can be accurately used in subsequent calculation processes.

[0137] S5, constructing a compressor pump body friction pair accelerated wear model and calculating the acceleration index κ, specifically including the following sub-steps:

[0138] S51. Construct the accelerated wear model of the compressor pump body friction pair as follows:

[0139]

[0140] Among them, F i 、F j are the maximum gas forces on the friction pair under the i-th and j-th working conditions, respectively, n i 、n j are the rotation frequencies of the compressor pump body under the i-th working condition and the j-th working condition respectively, and κ is the acceleration index.

[0141] The specific construction process is as follows:

[0142] Firstly, the general equation of the accelerated wear model of the compressor pump body friction pair is constructed based on the adhesive wear failure mechanism model.

[0143] The general relationship between the amount of wear on the friction surface that undergoes adhesive wear per unit sliding distance and the contact pressure is:

[0144] I=KP κ

[0145] Where K is the wear coefficient, which is related to structural parameters and working conditions such as material hardness, surface roughness, lubrication state, etc. P is the surface contact pressure, which is determined by external load conditions; κ is related to the part structure and is generally determined through experiments.

[0146] Secondly, taking the same total wear amount as the equivalent basis for the accelerated test, we have:

[0147]

[0148] In the formula, K ALT , K0 represent the wear coefficients under accelerated working condition and normal working condition respectively; They represent the unit contact pressure under acceleration and normal conditions respectively; S represents the relative sliding displacement of the friction pair after one rotation of the pump body; t ALT , t0 represent the time required to achieve the same amount of wear under accelerated conditions and normal conditions respectively.

[0149] Finally, in the accelerated experiment, by constraining the range of pressure and temperature, the wear mechanism of the friction pair is ensured to be similar to the lubrication state, and it can be considered that K ALT=K0, at the same time, S is only related to the structural size and has nothing to do with the working conditions, then:

[0150]

[0151] Right now:

[0152]

[0153] Based on the above formula, the accelerated wear model of the compressor pump body friction pair can be obtained.

[0154] S52, carrying out a wear experiment to determine the power exponent κ of the accelerated wear model, specifically comprising the following steps:

[0155] S521. Carry out the compressor wear test under two acceleration conditions, with at least three samples in each condition. Stop the test when any performance of the compressor decays by more than 5%. After the test, test the wear amount of the friction pair of each sample:

[0156] (1) Observe the worn area and find the worn edge.

[0157] (2) Observe the worn edge under an ultra-depth microscope to find the height step formed by the wear on the surface, and use the height difference as the wear amount at the current position. For those with unclear worn edges, use the height difference in the width direction of the worn area as the wear amount.

[0158] (3) Take 3 to 4 points along the wear edge, select the test points as shown in Table 5, and determine the average wear amount of the friction pair. The wear amount test diagram is shown in Table 6.

[0159] Table 5

[0160] Test point 1 Test point 2 Test point 3 Test point 4 average value 1.589 6.769 7.883 4.509 5.188

[0161] Table 6

[0162]

[0163]

[0164] S522. Calculation of pseudo wear life of friction pairs of various samples:

[0165] Select the maximum wear amount of the friction pair among multiple samples as the reference wear amount Based on the assumption that the wear volume accumulates approximately linearly in the stable wear stage, the time for each friction pair of each experimental sample to reach the reference wear volume is extrapolated and calculated. The pseudo failure life of the friction pair of each sample is shown in Table 7.

[0166] Table 7

[0167]

[0168] S523, respectively determine the wear life distribution of the friction pair under two acceleration conditions:

[0169] Based on historical data, the wear life distribution obeys the Weibull distribution. Based on the pseudo life data of each sample, the maximum likelihood estimation method is used to estimate the life distribution of the sample under two accelerated working conditions, that is, to determine the shape parameters and scale parameters of the Weibull distribution. The working conditions and characteristic life of the two accelerated working conditions are shown in Table 8.

[0170] Table 8

[0171]

[0172]

[0173] Specifically, the Van Montfort test method is used to test whether the life distribution obeys the Weibull distribution based on these r data. First, the null hypothesis is established:

[0174] H0: The life of the product follows a Weibull distribution.

[0175] W(β,η)

[0176] make

[0177]

[0178] They are the order statistics of extreme value distribution and standard extreme value distribution, where μ = lnη and σ = 1 / β are unknown parameters. Construct VanMontfort statistic:

[0179]

[0180] When the null hypothesis H0 is established, G i Asymptotically independent and asymptotically follows a standard exponential distribution, that is, a χ with 2 degrees of freedom 2 Distribution, G i If the two groups are equally divided, the statistics are:

[0181]

[0182] Asymptotically follows an F distribution with 2(rr′-1),2r′ degrees of freedom, where For a given significance level α, if:

[0183] F 1-α / 2 (2(rr′-1),2r′)<F<F α / 2 (2(rr′-1),2r′).

[0184] The null hypothesis H0 is considered to be valid, and the truncated sample comes from the Weibull distribution, where F α (f1, f2) is the α quantile of the F distribution with degrees of freedom f1 and f2. For α = 0.1, 0.05, 0.01, its value can be found in the "F distribution critical value table". The test results of each friction pair are shown in Table 9.

[0185] Table 9

[0186]

[0187] S524. Determine the wear life distribution of the friction pair under two acceleration conditions.

[0188] From the acceleration equation, we can know that when the friction pair reaches the same wear state under multiple working conditions, we have:

[0189] (F 1 ) κ ×n×t0=(F 2 ) κ ×n′×t ALT =C

[0190] For the expression (F i ) κ ×n i ×t i =C Taking the logarithm of both sides, we get:

[0191] Ln(n i t i )=Ln(C)-κLn(F i ).

[0192] It can be seen that the accelerated wear model is a linear function in double logarithmic coordinates, and the slope κ and intercept Ln(C) are unknown variables. At this time, we have obtained the time t required for the friction pair to reach the same wear state under at least two working conditions based on experimental data. i , and the contact force F of the friction pair under various working conditions is known i , rotation frequency n i , we can substitute into the expression to determine the acceleration exponent κ = 9.67.

[0193] S6. Calculate the acceleration factor. The specific steps of this embodiment are as follows:

[0194] Collect the rated operating conditions and structural parameters of the compressor, including the rated operating conditions and structural parameters of the compressor

[0195] Including: rated working condition suction pressure, rated working condition exhaust pressure, rated working condition rotation frequency, cylinder inner radius, roller sleeve outer radius, cylinder depth and the angle between the lower edge of the suction port and the center line of the blade. In this embodiment, the rated working conditions and structural parameters of the compressor are collected as shown in Table 10.

[0196] Table 10

[0197]

[0198]

[0199] Use the following formula to substitute the rated operating suction pressure P b =0.7Mpa, rated exhaust pressure P d =4.2Mpa, operating frequency 85Hz, and the values ​​of structural parameters R = 0.024m, r = 0.018m, H = 0.015m, β = 28°. Solve θ with the help of Matlab and other computing tools d =217.4°.

[0200]

[0201]

[0202] Calculate the maximum pressure P of the cylinder compression chamber under rated working conditions max In this embodiment, the following formula is used to calculate the result P max =7.5Mpa:

[0203]

[0204] The maximum gas force F on the friction pair under rated working conditions is calculated using the following formula: 额 (N):

[0205]

[0206] Determine the experimental acceleration condition parameters, including: acceleration condition suction pressure P b ', the unit is MPa. In this embodiment, according to the restricted use conditions / overload use conditions, under the condition of ensuring that the pressure ratio does not exceed the allowable value, the suction pressure takes the minimum limit value, which is 0.5 MPa in this embodiment.

[0207] Exhaust pressure P under acceleration d ', the unit is MPa. In this embodiment, according to the restricted use condition / overload use condition, the exhaust pressure takes the maximum limit value, which is 4.2 MPa in this embodiment.

[0208] The acceleration condition rotation frequency n' is in Hz. In this embodiment, the operating frequency takes the maximum limit value, which is 110 Hz in this embodiment.

[0209] Calculate the angle θ at which the cylinder compression chamber reaches the exhaust pressure under acceleration conditions d ′.

[0210] Calculate the maximum pressure P of the cylinder compression chamber under acceleration conditions max ′.

[0211]

[0212] Calculate the maximum gas force F on the friction pair of the compressor pump body under acceleration conditions 实 :

[0213]

[0214] Calculate the acceleration factor A of the pump friction pair using the following formula: PRE :

[0215]

[0216] It can be seen from the above embodiments that the present invention directly calculates the compressor pump body friction pair acceleration factor through a calculation formula, and the acceleration index is obtained through simulation analysis, which does not require a large number of experimental samples, and the calculation process is faster and more accurate. In addition, the calculation formula for the compressor pump body friction pair acceleration factor takes into account the mechanism influence, and the determined acceleration factor can be applied in multiple scenarios.

[0217] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for determining the acceleration factor of a compressor pump friction pair based on an accelerated wear model, characterized in that: It includes the following steps: S1. Collect the rated operating conditions and structural parameters of the compressor, wherein the rated operating conditions and structural parameters of the compressor include: rated operating suction pressure, rated operating exhaust pressure, rated operating rotation frequency, cylinder inner radius, roller sleeve outer radius, cylinder depth, and the angle between the lower edge of the suction port and the center line of the blade; S2, determining a first acceleration operating condition and a second acceleration operating condition, and determining the intake pressure, exhaust pressure and rotation frequency of the first acceleration operating condition and the second acceleration operating condition respectively; S3, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model and solving the compression index m specifically includes the following sub-steps: S31, construct the angle θ at which the cylinder compression chamber reaches the exhaust pressure d i The calculation model is: In the formula, in, is the suction pressure of the i-th working condition, is the exhaust pressure of the i-th working condition, R is the inner radius of the cylinder, r is the outer radius of the roller sleeve, H is the cylinder depth, β is the angle between the lower edge of the suction port and the center line of the blade, and m is the compression index; S32. The calculation formula for constructing the compression index m is as follows: S33, performing simulation analysis to obtain the angle at which the cylinder compression chamber reaches the exhaust pressure and bringing it into the calculation formula of step S31 to obtain the value of the compression index m; S4, using the calculation model in step S3, respectively calculate the angle θ at which the cylinder compression chamber reaches the exhaust pressure under the first acceleration condition and the second acceleration condition. d 1 and θ d 2 ; S5, constructing a compressor pump body friction pair accelerated wear model and calculating the acceleration index κ, specifically including the following sub-steps: S51. Construct the accelerated wear model of the compressor pump body friction pair as follows: Among them, F i 、F j are the maximum gas forces on the friction pair under the i-th and j-th working conditions, respectively. j is a working condition different from i, and n i 、n j are the rotation frequencies of the compressor pump body under the i-th and j-th working conditions, respectively, and κ is the acceleration index; S52, conducting a wear experiment to determine the acceleration index κ; S6. Based on the rated operating condition and the experimental accelerated operating condition, the compressor pump body friction pair accelerated wear model determined in step S5 is used to calculate the compressor pump body friction pair acceleration factor.

2. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 1 is characterized in that: The maximum gas force F exerted on the friction pair under condition i in step S51 i The calculation formula is: Among them, P max i is the maximum pressure of the cylinder compression chamber under condition i, and b is the fitting parameter.

3. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 2 is characterized in that: The maximum pressure of the cylinder compression chamber under condition i is P max i The calculation formula is:

4. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 1, characterized in that: The value of the compression index m is 1.6, the value of b is 0.18, and the value of the acceleration index κ is 9.

67.

5. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 1, characterized in that: In step S6, the compressor pump body friction pair acceleration factor A is calculated. PRE The specific calculation formula is: Among them, F 实 、F 额 are the maximum gas forces on the friction pair under experimental acceleration conditions and rated conditions, n 实 、n 额 They are the rotation frequencies of the compressor pump body under experimental acceleration conditions and rated conditions respectively.

6. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 1, characterized in that: In step S2, the intake pressure of the first acceleration condition is the minimum limit value, and the intake pressure of the second acceleration condition is 1.05-1.1 times the intake pressure of the first acceleration condition; The operating frequency of the second acceleration condition is the maximum limit value, and the operating frequency of the first acceleration condition is 0.75-0.8 times the operating frequency of the second acceleration condition; The first acceleration condition exhaust pressure and the first acceleration condition exhaust pressure both take maximum limit values.

7. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 1, characterized in that: Step S52 specifically includes the following sub-steps: S521, carrying out a compressor wear test under a first acceleration condition and a second acceleration condition respectively, selecting at least three samples for each acceleration condition, stopping the test when any performance of the compressor decays by more than 5%, and testing the wear amount of the friction pair of each sample after the test is completed; S522, calculating the pseudo wear life of the friction pairs of each sample; S523, respectively determining the wear life distribution of the friction pair under two acceleration conditions; S524. Determine the acceleration index κ based on the wear life distribution of the friction pair under two acceleration conditions. The calculation formula is as follows: Ln(n i t i )=Ln(C)-κLn(F i ) Among them, t i F is the time required for the friction pair to reach the expected wear state under the current working conditions. i is the maximum gas force on the friction pair under working condition i, and Ln(C) is the intercept.

8. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 1, characterized in that: In step S522, the maximum wear amount of the friction pair among the multiple samples is selected as the reference wear amount. Based on the assumption that the wear volume in the stable wear stage is approximately linearly accumulated, the time for each friction pair of each experimental sample to reach the reference wear volume is calculated. As the pseudo failure life of the friction pair of each sample; In step S523, based on the pseudo failure life of each sample, the maximum likelihood estimation method is used to estimate the life distribution of the sample under two acceleration conditions.

9. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 8, characterized in that: In step S524, when the friction pair reaches the same wear state under two acceleration conditions, the accelerated wear model is used to obtain: (F 1 ) κ ×n×t0=(F 2 ) κ ×n′×t ALT =C For the expression (F i ) κ ×n i ×t i =C Taking the logarithm of both sides, we get: Ln(n i t i )=Ln(C)-κLn(F i )。 10. The method for determining the acceleration factor of the compressor pump body friction pair based on the accelerated wear model according to claim 5, characterized in that: In step S6, the intake pressure, exhaust pressure and rotation frequency under the experimental acceleration condition are all obtained through experiments.

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