Evaluation method for effective temperature under double-flow cooling medium in rolling bearing bench test

Abstract

The invention discloses a rolling bearing bench test effective temperature evaluation method under a double-flow cooling medium. The method comprises the following steps: obtaining test basic parameters and test record parameters; calculating cooling air convection dissipation coefficients and cooling air convection heat dissipation power of the local test bed test at different environment temperatures when the local test bed test is compared with a nominal state; calculating the convection dissipation coefficient of the lubricating oil under the comparison between the local test bed test and the nominal state and the convection heat dissipation power of the lubricating oil during the local test bed test at different oil inlet temperatures; calculating the abrasion thermal power of the bearing in the nominal environment; according to a cooling air convection dissipation coefficient and a lubricating oil convection dissipation coefficient which are compared with a nominal state during a local test bed test, and the abrasion thermal power of the bearing in a nominal environment, the nominal state effective temperature of the bearing under the influence of real-time convection dissipation and lubricating medium fluid power loss is evaluated; and evaluating whether the nominal state effective temperature meets the existing standard. According to the invention, the defect that the effective temperature of the test bearing under the double-flow cooling medium (cooling air and lubricating oil) of the locomotive gearbox bearing test bed cannot be correctly evaluated according to the current domestic and international standards is overcome.

Description

Technical Field

[0001] This invention relates to the field of bearing testing technology, and in particular to a method for evaluating the effective temperature of rolling bearings under dual-flow cooling medium in a test bench. Background Technology

[0002] Since bearing temperature rise depends on the bearing's own frictional heat generation and the heat removed by external cooling conditions, in the field of bearing testing based on rolling bearing benches, the assessment of the wear and heat generation reliability of rolling bearings (such as axial force bearings) in railway locomotives and rolling stock typically involves simulating line operating conditions such as load and speed, as well as simulating the effect of running wind generated during train operation on bearing heat dissipation. The bearing temperature is measured to characterize the heat generation of the bearing, in order to identify the compatibility between the rolling bearing and the locomotive and rolling stock. However, because the simulated running wind conditions are relatively simple and the cooling capacity of the running wind is not measured in detail, this can lead to different bearing temperature rises under different ambient temperatures, resulting in inaccurate test results. Although domestic railway industry rolling bearing test method standards (such as the TB / T 3017.1-2016 series of standards) and international standards (such as BS EN 12082:2017 + A1:2021, UIC 515-5, NF F18-201, etc.) all equate the measured bearing temperature under different ambient temperatures to a standard effective temperature of 20 degrees Celsius to eliminate the influence of ambient temperature differences on bearing temperature measurement. This allows bearing temperature data under different operating conditions to be compared and analyzed under a unified benchmark, and provides calculation formulas for each. T Z20 = T zm –0.6×( T a –20) or i 有效 = i 实测 –( i 环境 -20℃), among which T Z20 and i 有效 Indicates the effective temperature after conversion. T zm and i 实测 This represents the actual measured bearing temperature. T a or i 环境The formula represents the actual ambient temperature, but it can be seen from the two formulas that there are differences in the methods of correcting the measured temperature in different standards. At the same time, the influence coefficient of 0.6 given in BS EN 12082:2017 + A1:2021 does not explain its source in depth.

[0003] Furthermore, existing standards for bearing testing primarily involve grease lubrication, where there is no heat exchange between the lubricating medium and the external environment. However, in gearbox testing, the lubricating medium is lubricating oil, which is continuously supplied by an external gear pump and requires cooling. Since the lubricating oil exchanges heat with the external environment, this inevitably affects the bearing's operating temperature. The working viscosity of the lubricating oil also significantly impacts bearing heating. However, existing gearbox bearing tests, when evaluating the effective temperature of bearing heating indicators, not only neglect the effects of lubricating oil heat exchange and working viscosity on bearing heating, but also struggle to determine the nominal effective temperature of the bearing under the input lubricating oil temperature and the ambient temperature of the cooling air. This leads to inconsistencies in bearing frictional heat generation and changes in the properties of the cooling fluid, ultimately resulting in unverifiable test results. Therefore, eliminating these two systematic errors in the test results is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This invention provides a method for evaluating the effective temperature of rolling bearings under dual-flow cooling medium in a test bench, in order to overcome the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A method for evaluating the effective temperature of rolling bearings under dual-flow cooling medium in a bench test, comprising the following steps: S1. Obtain basic test parameters and test record parameters based on bench tests of rolling bearings for gearboxes in locomotives and rolling stock; S2. Based on the basic test parameters and test record parameters, calculate the cooling air convection dissipation coefficient and cooling air convection heat dissipation power of the local test bench under different ambient temperatures, compared with the nominal state. S3. Based on the basic test parameters and test record parameters, calculate the lubricating oil convection dissipation coefficient and the lubricating oil convection heat dissipation power under different oil inlet temperatures, compared with the nominal state during the local test bench test; S4. Calculate the wear heat power of the bearing under the nominal environment based on the cooling air convection heat dissipation power and lubricating oil convection heat dissipation power during the test on the local test bench; S5. Evaluate the effective temperature of the bearing under nominal conditions based on the cooling air convection dissipation coefficient, lubricating oil convection dissipation coefficient, and bearing wear heat power under nominal conditions during the test on the local test bench compared with the nominal conditions, and assess the bearing's effective temperature under nominal conditions under real-time convection dissipation and the influence of fluid dynamic loss of lubricating medium, and give the evaluation result, namely whether the effective temperature of nominal conditions meets the existing standards.

[0006] Further, in S2, the cooling air convection dissipation coefficient is calculated based on the basic test parameters and test record parameters under different ambient temperatures, comparing the local test bench under the nominal conditions. The specific steps include: S21. Based on the ambient temperature at each moment T A ( t )Calculate each time point t air thermal conductivity The nominal air thermal conductivity at the nominal ambient temperature was calculated. The calculation formula is: , , in, This is the zero-point coefficient of the thermal conductivity of air. , and The units are all W / m·k; The slope of the air thermal conductivity as a function of ambient temperature, expressed in W / m·K. 2 ; The nominal ambient temperature, T A ( t )and All units are in °C; S22. Ambient temperature based on the ambient temperature at each moment. T A ( t )Calculate each time point t aerodynamic viscosity The nominal aerodynamic viscosity at the nominal ambient temperature was calculated. The calculation formula is: , , in, The zero-point coefficient of aerodynamic viscosity. , and The units are all kg / m·s. The slope of the aerodynamic viscosity as a function of ambient temperature is expressed in kg / m·s·k. S23. Based on the equivalent area of ​​the cooling airflow through the bearing housing of the local test bench. S A The equivalent diameter of the cooling air passing through the bearing housing was calculated. d A The calculation formula is: , in, d A The unit is m; S A The unit is m 2 ; S24. Based on the atmospheric pressure of the test site at each moment. P A ( t ), average molar mass coefficient of air M A The gas constant of air R A and the temperature of the cooling air passing through the bearing housing at each moment. T A,in ( t The cooling air density at each time point during the experiment was calculated. and based on the standard atmospheric pressure P A0 Average molar mass coefficient of air M A gas constant of air R A The cooling air density at the nominal ambient temperature was calculated. The calculation formula is: , , in, and The units are all kg / m³ 3 ; P A ( t )and P A0 The units are all N / m 2 ; M A The unit is g / mol; R A The unit is J / mol·k; T A,in ( t The unit is ℃; S25. Based on the cooling air density at each time point during the aforementioned experiment. r a ( t The average velocity of the cooling airflow through the bearing housing at each moment on the test bench. V A ( t The equivalent diameter of the cooling air passing through the bearing housing d A and aerodynamic viscosity at each point in time m a ( t The Reynolds coefficients of the cooling wind at each time point during the experiment were calculated. Re a ( t ), and based on the Reynolds coefficient of the cooling wind at each time point during the test. Re a ( t Obtain the Reynolds index at each time point. n A ( t The calculation formula is: , in, Re a ( t Dimensionless V A ( t The unit of ) is m / s; S26. Based on the cooling air density at each time point during the aforementioned experiment. r a ( t The average velocity of the cooling airflow through the bearing housing at each moment on the test bench. V A ( t The equivalent area of ​​the local test bench cooling airflow through the bearing housing S A The mass flow rate of cooling air passing through the bearing housing at each time point during the experiment was calculated. and cooling air density based on nominal ambient temperature. r a,0 The average velocity of the cooling airflow through the bearing housing as specified in the standard test bench V 0 and the equivalent area of ​​the cooling airflow over the bearing housing as specified in the standard test bench. S A0 The mass flow rate of cooling air passing through the bearing housing at the nominal ambient temperature was calculated. The calculation formula is: , , in, and The units are all kg / s; V The unit of 0 is m / s; S A0 The unit is m 2 ; S27. Based on the air thermal conductivity at each of the aforementioned time points Nominal thermal conductivity of air at nominal ambient temperature Mass flow rate of cooling air passing through the bearing housing at various time points during the test. Mass flow rate of cooling air passing through the bearing housing at nominal ambient temperature Reynolds Index n A ( t Aerodynamic viscosity at each time point and nominal aerodynamic viscosity at nominal ambient temperature The cooling air convection dissipation coefficient was calculated under the local test bench conditions compared with the nominal conditions. The calculation formula is: .

[0007] Further, in S2, the cooling air convection heat dissipation power during local test bench testing at different ambient temperatures is calculated based on the aforementioned basic test parameters and test record parameters. The specific steps include: Based on the temperature of the cooling air passing through the bearing housing at each given moment... T A,in ( t (and the outlet cooling air temperature of the cooling air after passing through the bearing housing under test at each moment) T A,out ( t The specific heat capacity of the cooling air convective heat during the local test bench test was calculated. ; , in, The specific heat capacity of air at zero temperature. and The units are all kJ / kg.k; Based on the convective heat specific volume of the cooling air during the test on the local test bench. C A (t) Mass flow rate of cooling air through the bearing housing at each time point during the test The temperature of the cooling air passing through the bearing housing at each moment. T A,in ( t (and the outlet cooling air temperature of the cooling air after passing through the bearing housing under test at each moment)T A,out ( t The cooling air convection heat dissipation power during the local test bench test was calculated using the following formula: .

[0008] Further, in S3, based on the aforementioned basic test parameters and test record parameters, the lubricating oil convection dissipation coefficient is calculated under different inlet temperatures, comparing the local test bench test conditions with the nominal conditions. The specific steps include: S31. Based on the brand of the tested lubricating oil and the heat exchange technical parameters, calculate the lubricating oil at the average operating temperature at each time point t. T O,in ( t )+ T O,out ( t Thermal conductivity at )] / 2 and the nominal average operating temperature of the lubricating oil [ T O,in ( t )+ T O,out ( t The nominal thermal conductivity at )] / 2 : S32. Based on the brand of the test lubricating oil and the heat exchange technical parameters, calculate the average operating temperature of the lubricating oil at each time point t. T O,in ( t )+ T O,out ( t Dynamic viscosity at )] / 2 Iterative calculation of nominal ambient lubricating oil outlet temperature T O,0,out ( t ) and the nominal average ambient operating temperature [ T O,in ( t )+ T O,out ( t The nominal dynamic viscosity of the lubricating oil at )] / 2 ; S33. Based on the brand of the test lubricating oil and the heat transfer technical parameters, calculate the density of the lubricating oil at each time point during the test. and the nominal ambient temperature of the lubricating oil T O0 The density of the lubricating oil below ; S34. Based on the lubricating oil density at each time point during the experiment. and the flow rate of lubricating oil through the bearing on the test bench at each moment Calculate the mass flow rate of lubricating oil through the bearing at each time point during the experiment. Based on the nominal ambient temperature of the lubricating oil T O0 The density of the lubricating oil below The flow rate of the lubricating oil through the bearing as specified in the nominal value. Calculate the nominal ambient temperature T O0 Mass flow rate of lubricating oil through the bearing The calculation formula is: , , S35. Based on each time point t The lubricating oil at the average operating temperature [ T O,in ( t )+ T O,out ( t Thermal conductivity at )] / 2 l O ( t ), nominal ambient temperature of lubricating oil T O0 The nominal thermal conductivity of the lubricating oil is as follows At each point in time t The average operating temperature of the lubricating oil [ T O,in ( t )+ T O,out ( t Dynamic viscosity at )] / 2 Nominal average ambient operating temperature T O0 + T O,0,out ( t The nominal dynamic viscosity of the lubricating oil at )] / 2 Mass flow rate of lubricating oil through the bearing at various time points during the test. and nominal ambient temperature T O0 Mass flow rate of lubricating oil through the bearing Calculate the lubricating oil convection dissipation coefficient under local test bench conditions compared to nominal conditions. f OT ( t The calculation formula is: , in, and The units are all W / m·k; and The units are all kg / s; and The units are all kg / m·s.

[0009] Furthermore, in S3, based on the aforementioned basic test parameters and test record parameters, the convective heat dissipation power of the lubricating oil during the local test bench test at different oil inlet temperatures is calculated. The specific steps include: Calculate the average operating temperature of the lubricating oil during local test bench testing. T O,in ( t )+ T O,out ( t ]] / 2 convective heat specific volume ; Based on the temperature of the inlet lubricating oil before it passes through the bearing under test at each moment. T O,in ( t (and the outlet lubricating oil temperature of the lubricating oil after passing through the tested bearing at each moment) T O,out ( t Mass flow rate of lubricating oil through the bearing at various time points during the test. and Calculate the lubricating oil convection heat dissipation power during local test bench testing. N O (t), the calculation formula is: , in, The unit is kJ / kg.k.

[0010] Further, in S4, the wear heat power of the bearing under nominal conditions is calculated based on the cooling air convection heat dissipation power and lubricating oil convection dissipation power during the local test bench test. The specific steps include: S41. Calculate the bearing at its average operating temperature. T O,in ( t )+ T O,out ( t Theoretical friction torque under )] / 2 M B (t), in N.mm, and the bearing's average operating temperature at the nominal ambient temperature. T O0 + T O,0,out ( t Theoretical friction torque under )] / 2 MB,0 (t), in N.mm; S42. Calculate the bearing's average operating temperature at the nominal ambient temperature. T O0 + T O,0,out ( t Wear heat power at )] / 2 N B,0 (t), the calculation formula is: , in, N B,0 The unit of (t) is kW.

[0011] Further, in S5, based on the cooling air convection dissipation coefficient, lubricating oil convection dissipation coefficient, and bearing wear heat power under nominal conditions compared with the local test bench test, the effective temperature of the bearing under nominal conditions is evaluated under real-time convection dissipation and the influence of lubricating medium hydrodynamic loss. The specific steps include: S51. Calculate the nominal effective temperature at each measuring point under dual-flow cooling medium during local test bench testing, under the influence of real-time convection dissipation and lubricating medium hydrodynamic losses. The calculation formula is: , in, The unit is ℃; S52. If the cooling state of the lubricating oil is set to standard conditions, then the changes in the cooling properties of the lubricating oil and the effects of hydrodynamic losses of the lubricating medium can be ignored. Therefore, the above formula can be simplified to: , S53. Determine the effective temperature of each measuring point under nominal conditions. Determine whether the value is lower than the specified value required by the standard, and provide the evaluation result.

[0012] Beneficial effects: This invention provides a method for evaluating the effective temperature of test bearings under dual-flow cooling media (cooling air and lubricating oil) on a locomotive and rolling stock gearbox bearing test bench. By comparing the bearing heating state under different ambient temperatures and lubricating fluids with the bearing heating under standard conditions, and comparing the cooling and heat dissipation under test conditions with the cooling and heat dissipation under standard conditions, the method uniformly converts the temperature to the test temperature under standard conditions, eliminating systematic errors in test conditions. Furthermore, based on the analysis of air cooling heat transfer and lubricating oil cooling, the method considers the influence of lubricating oil working viscosity on bearing heating, thus overcoming the shortcomings of current domestic and international standards that cannot accurately evaluate the effective temperature of test bearings under dual-flow cooling media (cooling air and lubricating oil) on a locomotive and rolling stock gearbox bearing test bench. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a method for evaluating the effective temperature of a rolling bearing under dual-flow cooling medium in a test bench according to the present invention; Figure 2 This is a schematic diagram of the test principle of the locomotive and rolling stock gearbox bearing test bench in an embodiment of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] This embodiment provides a method for evaluating the effective temperature of rolling bearings under dual-flow cooling medium in a bench test, such as... Figure 1 and Figure 2 As shown, the specific steps include: S1. Obtain basic test parameters and test record parameters based on bench tests of rolling bearings for gearboxes in locomotives and rolling stock; The basic parameters include the gas constant of air, the average molar mass coefficient of air, the standard atmospheric pressure, the equivalent area of ​​the local test bench cooling air flowing through the bearing housing, the equivalent area of ​​the test bench cooling air flowing through the bearing housing as specified in the standard, the nominal ambient temperature of the cooling air during the test, the specific heat capacity of air at the nominal ambient temperature, the nominal ambient temperature of the lubricating oil during the test, the specific heat capacity of the lubricating oil at the nominal ambient temperature, and the specified flow rate of the lubricating oil through the bearing at the nominal temperature. The test recording parameters include the temperature of each measuring point of the bearing at each moment, the temperature of the cooling air before passing through the bearing housing at each moment, the outlet temperature of the cooling air after passing through the bearing housing at each moment, the average speed of the cooling air flowing through the bearing housing at each moment, the average speed of the cooling air flowing through the bearing housing at each moment as specified in the standard, the atmospheric pressure of the test site at each moment, the temperature of the inlet lubricating oil before passing through the bearing at each moment, the outlet temperature of the lubricating oil after passing through the bearing at each moment, and the flow rate of the lubricating oil flowing through the bearing at each moment. S2. Based on the basic test parameters and test record parameters, calculate the cooling air convection dissipation coefficient and cooling air convection heat dissipation power of the local test bench under different ambient temperatures, compared with the nominal state. S3. Based on the basic test parameters and test record parameters, calculate the lubricating oil convection dissipation coefficient and the lubricating oil convection heat dissipation power under different oil inlet temperatures, compared with the nominal state during the local test bench test; S4. Calculate the wear heat power of the bearing under the nominal environment based on the cooling air convection heat dissipation power and lubricating oil convection dissipation power during the test on the local test bench; S5. Based on the cooling air convection dissipation coefficient, lubricating oil convection dissipation coefficient, and bearing wear heat power under nominal conditions compared with the test conditions on the local test bench, evaluate the nominal effective temperature of the bearing under real-time convection dissipation and the influence of fluid dynamic loss of the lubricating medium, and evaluate whether the nominal effective temperature meets the existing standards.

[0017] Specifically, this embodiment utilizes the fundamental principle that heat generation equals heat dissipation, and the relationship between temperature, heat generation, and heat transfer performance, to establish a corresponding calculation model to calculate the nominal effective temperature at each measurement point under dual-flow cooling media (cooling air and lubricating oil) during local test bench testing, under the influence of real-time convection dissipation and lubricating medium hydrodynamic losses. It also determines whether the nominal effective temperature is lower than the specified value required by the standard, thereby achieving an accurate evaluation of the bearing test.

[0018] In a specific embodiment, S2 involves calculating the cooling air convection dissipation coefficient under different ambient temperatures at the local test bench, compared to the nominal state, based on the basic test parameters and test record parameters. The specific steps include: S21. Based on the ambient temperature at each moment T A ( t )Calculate each time point t air thermal conductivity l a ( t The nominal air thermal conductivity at the nominal ambient temperature was calculated. l a,0 The calculation formula is: , , in, This is the zero-point coefficient of the thermal conductivity of air, with units of W / m·K, and a value of [value missing]. ; The slope of the air thermal conductivity as a function of ambient temperature, expressed in W / m·K. 2 The value is ; The nominal ambient temperature is set to 20. S22. Based on the ambient temperature at each moment T A ( t )Calculate each time point t aerodynamic viscosity m a ( t The nominal aerodynamic viscosity at the nominal ambient temperature was calculated. The calculation formula is: , , in, This is the zero-point coefficient of aerodynamic viscosity, with units of kg / m·s, and a value of [value missing]. ; The slope of aerodynamic viscosity as a function of ambient temperature, expressed in kg / m·s·k, is given by values ​​[value missing]. ; S23. Based on the equivalent area of ​​the cooling airflow through the bearing housing of the local test bench. S A The equivalent diameter of the cooling air passing through the bearing housing was calculated. d A The calculation formula is: , S24. Based on the atmospheric pressure of the test site at each moment. P A ( t ), average molar mass coefficient of air M A The gas constant of air R A and the temperature of the cooling air passing through the bearing housing at each moment. T A,in ( t The cooling air density at each time point during the experiment was calculated. r a ( t ), and based on the standard atmospheric pressure P A0 Average molar mass coefficient of air M A gas constant of air R A The cooling air density at the nominal ambient temperature was calculated. r a,0 The calculation formula is: , , S25. Based on the cooling air density at each time point during the aforementioned experiment. r a ( t The average velocity of the cooling airflow through the bearing housing at each moment on the test bench. V A ( t The equivalent diameter of the cooling air passing through the bearing housing d A and aerodynamic viscosity at each point in time m a ( t The Reynolds coefficients of the cooling wind at each time point during the experiment were calculated. Re a ( t ), and based on the Reynolds coefficient of the cooling wind at each time point during the test. Re a ( t Obtain the Reynolds index at each time point. n A ( t The calculation formula is: , Specifically, in this embodiment, when 10 3 ≤ Re a (t )<2×10 4 hour, n A ( t ) = 0.65; when 2 × 10 4 ≤ Re a ( t )<2×10 5 hour, n A ( t )=0.8; when Re a ( t )≥2×10 5 hour, n A ( t =0.95.

[0019] S26. Based on the cooling air density at each time point during the aforementioned experiment. r a ( t The average velocity of the cooling airflow through the bearing housing at each moment on the test bench. V A ( t The equivalent area of ​​the local test bench cooling airflow through the bearing housing S A The mass flow rate of cooling air passing through the bearing housing at each time point during the experiment was calculated. and cooling air density based on nominal ambient temperature. r a,0 The average velocity of the cooling airflow through the bearing housing as specified in the standard test bench V 0 and the equivalent area of ​​the cooling airflow over the bearing housing as specified in the standard test bench. S A0 The mass flow rate of cooling air passing through the bearing housing at the nominal ambient temperature was calculated. The calculation formula is: , , S27. Based on the air thermal conductivity at each of the aforementioned time points l a ( t Nominal thermal conductivity of air at nominal ambient temperature l a,0 Mass flow rate of cooling air passing through the bearing housing at various time points during the test. Mass flow rate of cooling air passing through the bearing housing at nominal ambient temperature Reynolds Index n A (t Aerodynamic viscosity at each time point m a ( t and nominal aerodynamic viscosity at nominal ambient temperature The cooling air convection dissipation coefficient under local test conditions compared to nominal conditions was calculated using the following formula: .

[0020] In a specific embodiment, S2 involves calculating the cooling air convection heat dissipation power during local test bench testing at different ambient temperatures based on the basic test parameters and test record parameters. The specific steps include: Based on the temperature of the cooling air passing through the bearing housing at each given moment... T A,in ( t (and the outlet cooling air temperature of the cooling air after passing through the bearing housing under test at each moment) T A,out ( t The specific heat capacity of the cooling air convective heat during the local test bench test was calculated. C A (t); , in, The specific heat capacity of air at zero temperature. The unit is kJ / kg.k, and the value is... ; Based on the convective heat specific volume of the cooling air during the test on the local test bench. C A (t) Mass flow rate of cooling air through the bearing housing at each time point during the test The temperature of the cooling air passing through the bearing housing at each moment. T A,in ( t (and the outlet cooling air temperature of the cooling air after passing through the bearing housing under test at each moment) T A,out ( t The cooling air convection heat dissipation power during the local test bench test was calculated using the following formula: .

[0021] Specifically, this embodiment calculates the convective scattering coefficient and convective heat dissipation power of the cooling air under the test conditions of the local test bench compared with the nominal conditions, thereby analyzing the impact of different ambient temperatures on the convective dissipation power of the cooling air.

[0022] In a specific embodiment, in S3, the lubricating oil convection dissipation coefficient is calculated based on the basic test parameters and test record parameters at different oil inlet temperatures, comparing the local test bench test with the nominal state. The specific steps include: S31. Based on the brand of the tested lubricating oil and the heat exchange technical parameters, calculate the lubricating oil at the average operating temperature at each time point t. T O,in ( t )+ T O,out ( t Thermal conductivity at )] / 2 and the nominal average operating temperature of the lubricating oil [ T O,in ( t )+ T O,out ( t The nominal thermal conductivity at )] / 2 : S32. Based on the brand of the test lubricating oil and the heat exchange technical parameters, calculate the average operating temperature of the lubricating oil at each time point t. T O,in ( t )+ T O,out ( t Dynamic viscosity at )] / 2 Iterative calculation of nominal ambient lubricating oil outlet temperature T O,0,out ( t ) and the nominal average ambient operating temperature [ T O,in ( t )+ T O,out ( t The nominal dynamic viscosity of the lubricating oil at )] / 2 ; S33. Based on the brand of the test lubricating oil and the heat transfer technical parameters, calculate the density of the lubricating oil at each time point during the test. and the nominal ambient temperature of the lubricating oil T O0 The density of the lubricating oil below ; Specifically, the above data on lubricating oil can be obtained from the respective lubricating oil manufacturers, and calculations are omitted here.

[0023] S34. Based on the lubricating oil density at each time point during the experiment. and the flow rate of lubricating oil through the bearing on the test bench at each moment Calculate the mass flow rate of lubricating oil through the bearing at each time point during the experiment. Based on the nominal ambient temperature of the lubricating oil T O0 The density of the lubricating oil below The flow rate of the lubricating oil through the bearing as specified in the nominal value. Calculate the nominal ambient temperature T O0 Mass flow rate of lubricating oil through the bearing The calculation formula is: , , S35. Based on each time point t The lubricating oil at the average operating temperature [ T O,in ( t )+ T O,out ( t Thermal conductivity at )] / 2 l O ( t ), nominal ambient temperature of lubricating oil T O0 The nominal thermal conductivity of the lubricating oil is as follows At each point in time t The average operating temperature of the lubricating oil [ T O,in ( t )+ T O,out ( t Dynamic viscosity at )] / 2 m O ( t ), nominal average ambient operating temperature[ T O0 + T O,0,out ( t The nominal dynamic viscosity of the lubricating oil at )] / 2 Mass flow rate of lubricating oil through the bearing at various time points during the test. and nominal ambient temperature T O0 Mass flow rate of lubricating oil through the bearing Calculate the lubricating oil convection dissipation coefficient under local test bench conditions compared to nominal conditions. f OT ( t The calculation formula is: .

[0024] In a specific embodiment, S3 involves calculating the lubricating oil convection cooling power under different inlet temperatures during local test bench testing, based on the basic test parameters and test record parameters. The specific steps include: Calculate the average operating temperature of the lubricating oil during local test bench testing. T O,in ( t )+ T O,out ( t ]] / 2 convective heat specific volume ; Based on the temperature of the inlet lubricating oil before it passes through the bearing under test at each moment. T O,in ( t (and the outlet lubricating oil temperature of the lubricating oil after passing through the tested bearing at each moment) T O,out ( t Mass flow rate of lubricating oil through the bearing at various time points during the test. and Calculate the lubricating oil convection heat dissipation power during local test bench testing. N O (t), the calculation formula is: .

[0025] Specifically, this embodiment calculates the convective heat dissipation power of the lubricating oil during local test bench testing, thereby analyzing the impact of different inlet temperatures on the cooling power of the lubricating oil.

[0026] In a specific embodiment, S4 involves calculating the wear heat power of the bearing under nominal conditions based on the cooling air convection heat dissipation power and lubricating oil convection dissipation power during the local test bench test. The specific steps include: S41. Calculate the bearing at its average operating temperature. T O,in ( t )+ T O,out ( t Theoretical friction torque under )] / 2 M B (t), and the bearing's average operating temperature at the nominal ambient temperature [ T O0 + T O,0,out ( t Theoretical friction torque under )] / 2 M B,0 (t); S42. Calculate the bearing's average operating temperature at the nominal ambient temperature. T O0 +T O,0,out ( t Wear heat power at )] / 2 N B,0 (t), the calculation formula is: .

[0027] Specifically, this embodiment considers different lubrication and heat dissipation conditions, calculates the theoretical frictional torque of the bearing under standard conditions, and analyzes how these factors affect the bearing's frictional torque (and frictional heat generation). It should be noted that... M B (t) and M B,0 The calculation method for (t) is a common method in the bearing industry, and will not be elaborated here.

[0028] In a specific embodiment, S5 involves evaluating the effective temperature of the bearing under nominal conditions based on the cooling air convection dissipation coefficient, lubricating oil convection dissipation coefficient, and the bearing wear heat power under nominal conditions, compared with the nominal conditions during the local test bench test. The evaluation also assesses whether the effective temperature of the nominal conditions meets existing standards. The specific steps include: S51. Calculate the nominal effective temperature at each measuring point under dual-flow cooling media (cooling air and lubricating oil) during local test bench testing, under the influence of real-time convection dissipation and lubricating medium hydrodynamic losses. The calculation formula is: , S52. Considering the complexity of iterative calculations, this embodiment sets the experiment so that if the cooling state of the lubricating oil can be controlled within the standard-specified state or permissible error, the changes in the cooling properties of the lubricating oil and the effects of hydrodynamic losses of the lubricating medium can be ignored. Therefore, the above formula can be simplified to: , S53. Determine the effective temperature of each measuring point under nominal conditions. Whether it is below the specified value required by the standard, thereby assessing the wear and temperature rise state during bearing testing.

[0029] Specifically, the parameter values ​​and units involved in this embodiment are shown in Tables 1 to 3; Table 1. Basic parameters for bench testing of rolling bearings for gearboxes in locomotives and rolling stock.

[0030] Table 2 Test Record Parameters for Rolling Bearings in Gearboxes of Locomotives and Rolling Stock

[0031] Table 3 Calculation parameters for bench tests of rolling bearings for locomotives and rolling stock gearboxes

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating an effective temperature under a dual flow cooling medium in a rolling bearing rig test, characterized by, The specific steps include: S1. Obtain test basic parameters and test record parameters based on a rolling bearing bench test for a gear box of a locomotive vehicle; S2. Calculate a cooling air convection dissipation coefficient under different ambient temperatures and a cooling air convection heat dissipation power under the local test bench test compared with a nominal state based on the test basic parameters and the test record parameters; S3. Calculate a lubricating oil convection dissipation coefficient under different oil inlet temperatures and a lubricating oil convection heat dissipation power under the local test bench test compared with the nominal state based on the test basic parameters and the test record parameters; S4. Calculate a wear heat power of the bearing under a nominal environment based on the cooling air convection heat dissipation power and the lubricating oil convection heat dissipation power under the local test bench test; S5. Evaluate a nominal state effective temperature of the bearing under real-time convection dissipation and influence of fluid dynamic loss of a lubricating medium according to the cooling air convection dissipation coefficient, the lubricating oil convection dissipation coefficient under the local test bench test compared with the nominal state, and the wear heat power of the bearing under the nominal environment, and give an evaluation result, that is, whether the nominal state effective temperature meets an existing standard.

2. The method of evaluating the effective temperature under the dual flow cooling medium in the rolling bearing rig test according to claim 1, characterized by, In S2, the cooling air convection dissipation coefficient under different ambient temperatures and the local test bench test compared with the nominal state is calculated based on the test basic parameters and the test record parameters, and the specific steps include: S21. Calculate the air heat transfer coefficient at each time point based on the ambient temperature at each time point T A ( t ) Calculate the air heat transfer coefficient at each time point t , and calculate the nominal air heat transfer coefficient at the nominal ambient temperature , the calculation formula is:​ ， ， wherein, is a zero point coefficient for the thermal conductivity of air, , and all have units of W / m-k; is a slope of the thermal conductivity of air as a function of ambient temperature, with units of W / m-k 2 ; is a nominal ambient temperature, T A ( t ) and all have units of °C; S22. Ambient temperature at each time point T A ( t ) Calculate the air dynamic viscosity at each time point t , and calculate the nominal air dynamic viscosity at the nominal ambient temperature , the calculation formula is:​ ， ， wherein is a zero point coefficient for the aerodynamic viscosity, , and all in kg / m-s, is a slope of the aerodynamic viscosity with respect to the ambient temperature in kg / m-s-k; S23. Equivalent area of the bearing housing through which the cooling air from the local test bench flows S A The equivalent diameter of the cooling air through the bearing housing is calculated d A The formula is: ， wherein d A in m; S A in m 2 ; S24. atmospheric pressure of the test site at each time point P A t , average molar mass coefficient of air M A , gas constant of air R A and temperature of cooling air before the bearing seat of the tested bearing at each time point T A,in t , cooling air density at each time point during the test is calculated , and cooling air density at the nominal ambient temperature is calculated based on the standard atmospheric pressure P A0 , average molar mass coefficient of air M A and gas constant of air R A , and the calculation formula is:​​​ ， ， wherein, and are each in kg / m 3 ; P A ( t ) and P A0 are each in N / m 2 ; M A is in g / mol; R A is in J / mol.k; T A,in ( t ) is in °C;​​ S25. calculating the cooling air Reynolds number at each time point during the test based on the cooling air density at each time point during the test ρ a ( t ), the average velocity of the cooling air flowing through the bearing housing at each time point during the test V A ( t ), the equivalent diameter of the cooling air through the bearing housing d A and the air dynamic viscosity at each time point μ a ( t ) Re a ( t ), and obtaining the Reynolds index at each time point according to the cooling air Reynolds number at each time point during the test Re a ( t ) n A ( t ), and the calculation formula is: ， wherein Re a ( t ) dimensionless, V A t in m / s;​ S26. cooling air density at each time point during the test ρ a ( t ) average velocity of the cooling air through the bearing housing at each time point during the test V A ( t ) and equivalent area of the cooling air through the bearing housing at each time point during the test S A S27. mass flow rate of the cooling air through the bearing housing at each time point during the test , calculated based on the cooling air density at each time point during the test ρ a,0 V 0 average velocity of the cooling air through the bearing housing at each time point during the test S A0 S28. mass flow rate of the cooling air through the bearing housing at each time point during the test , calculated based on the nominal ambient temperature, calculated formula:​ ， ， wherein, and all in kg / s; V 0 in m / s; S A0 in m 2 ; S27. air thermal conductivity at said each time point , nominal air thermal conductivity at nominal ambient temperature , mass flow rate of cooling air through the bearing housing at each time point during the test , mass flow rate of cooling air through the bearing housing at nominal ambient temperature , Reynolds number n A ( t ), air dynamic viscosity at said each time point and nominal air dynamic viscosity at nominal ambient temperature the cooling air convective dissipation coefficient at the local test bench during the test compared to the nominal state is calculated , according to the following formula: 。 3. The method of evaluating the effective temperature under the dual flow cooling medium of the rolling bearing test rig according to claim 2, characterized in that, In S2, the cooling air convection heat dissipation power under different ambient temperatures and the local test bench test is calculated based on the test basic parameters and the test record parameters, and the specific steps include: temperature of the cooling air after passing through the bearing housing of the test bearing at each time point T A,in ( t ) and the outlet cooling air temperature after the cooling air passing through the bearing housing of the test bearing at each time point T A,out ( t ) to calculate the local test bench test cooling air convective heat capacity ; ， wherein, Cp0is the specific heat capacity of air at zero temperature, and are expressed in kJ / kg.k; a cooling air convective heat capacity during the local test bench test based on the cooling air C A (t), a mass flow rate of the cooling air through the bearing housing at each time point during the test , a temperature of the cooling air before the test bearing housing at each time point during the test T A,in ( t ) and an outlet cooling air temperature after the test bearing housing at each time point during the test T A,out ( t ) a cooling air convective heat dissipation power during the local test bench test, and a calculation formula is: 。 4. The method of evaluating the effective temperature under the dual flow cooling medium of the rolling bearing test rig according to claim 3, characterized in that, In S3, the lubricating oil convection dissipation coefficient under different oil inlet temperatures and the local test bench test compared with the nominal state is calculated based on the test basic parameters and the test record parameters, and the specific steps include: S31. According to the brand of the test lubricating oil and the heat exchange technical parameter law, the heat conductivity coefficient of the lubricating oil at the average working temperature of the lubricating oil at each time point t is calculated T O,in ( t )+ T O,out ( t )] / 2 and the nominal heat conductivity coefficient of the lubricating oil at the nominal average working temperature of the lubricating oil of[ T O,in ( t )+ T O,out ( t )] / 2 : S32. Based on the brand of the test lubricating oil and the heat exchange technical parameters, calculate the average operating temperature of the lubricating oil at each time point t. T O,in ( t )+ T O,out ( t Dynamic viscosity at )] / 2 Iterative calculation of nominal ambient lubricating oil outlet temperature T O,0,out ( t ) and the nominal average ambient operating temperature [ T O,in ( t )+ T O,out ( t The nominal dynamic viscosity of the lubricating oil at )] / 2 ; S33. According to the brand of the test lubricating oil and the heat exchange technical parameter law, the lubricating oil density at each time point during the test is calculated and the lubricating oil density at the nominal ambient temperature of the lubricating oil T O0 ;​ S34. The density of the lubricating oil at each time point during the test and the flow rate of the lubricating oil through the bearing at each time point during the test The mass flow rate of the lubricating oil through the bearing at each time point during the test based on the nominal ambient temperature of the lubricating oil T O0 The density of the lubricating oil at the nominal ambient temperature and the flow rate of the lubricating oil through the bearing at the nominal ambient temperature The mass flow rate of the lubricating oil through the bearing at the nominal ambient temperature T O0 The mass flow rate of the lubricating oil through the bearing at the nominal ambient temperature The mass flow rate of the lubricating oil through the bearing at the nominal ambient temperature ， ， S35. Based on each time point t The lubricating oil at the average operating temperature [ T O,in ( t )+ T O,out ( t Thermal conductivity at )] / 2 λ O ( t ), nominal ambient temperature of lubricating oil T O0 The nominal thermal conductivity of the lubricating oil is as follows At each point in time t The average operating temperature of the lubricating oil [ T O,in ( t )+ T O,out ( t Dynamic viscosity at )] / 2 Nominal average ambient operating temperature T O0 + T O,0,out ( t The nominal dynamic viscosity of the lubricating oil at )] / 2 Mass flow rate of lubricating oil through the bearing at various time points during the test. and nominal ambient temperature T O0 Mass flow rate of lubricating oil through the bearing Calculate the lubricating oil convection dissipation coefficient under local test bench conditions compared to nominal conditions. f OT ( t The calculation formula is: ， wherein, and units are W / m·k; and units are kg / s; and units are kg / m·s.

5. The method of evaluating the effective temperature under the dual flow cooling medium of the rolling bearing test rig according to claim 4, characterized in that, In S3, the lubricating oil convection heat dissipation power under different oil inlet temperatures and the local test bench test is calculated based on the test basic parameters and the test record parameters, and the specific steps include: Average operating temperature of lubricating oil during calculation of the test on the local test bed T O,in ( t )+ T O,out ( t )] / 2 under the average operating temperature of lubricating oil during calculation of the test on the local test bed ; the temperature of the inlet lubricating oil before the passage of the lubricating oil through the bearing under test at each time instant T O,in ( t ) and the temperature of the outlet lubricating oil after the passage of the lubricating oil through the bearing under test at each time instant T O,out ( t ), the mass flow rate of the lubricating oil through the bearing at each time instant during the test and the convective heat dissipation power of the lubricating oil during the test on the local test bench N O (t), calculated according to the formula: ， wherein, in kJ / kg.k.

6. The method of evaluating the effective temperature under the dual flow cooling medium of the rolling bearing test rig according to claim 5, characterized in that, In S4, the wear heat power of the bearing under the nominal environment is calculated based on the cooling air convection heat dissipation power and the lubricating oil convection heat dissipation power under the local test bench test, and the specific steps include: S41. Calculate the bearing at the average operating temperature [ T O,in ( t )+ T O,out ( t Theoretical friction torque under )] / 2 M B (t), in N.mm, and the bearing's average operating temperature at the nominal ambient temperature. T O0 + T O,0,out ( t Theoretical friction torque under )] / 2 M B,0 (t), in N.mm; S42. Calculate the wear heat power of the bearing at the average working temperature of the bearing in the nominal environment T O0 + T O,0,out ( t )] / 2 N B,0 (t), the calculation formula is: ， wherein, N B,0 (t) is in kW.

7. The method of evaluating the effective temperature under the dual flow cooling medium of the rolling bearing test rig according to claim 6, characterized in that, In S5, the nominal state effective temperature of the bearing under real-time convection dissipation and influence of fluid dynamic loss of a lubricating medium is evaluated according to the cooling air convection dissipation coefficient, the lubricating oil convection dissipation coefficient under the local test bench test compared with the nominal state, and the wear heat power of the bearing under the nominal environment, and whether the nominal state effective temperature meets an existing standard is evaluated, and the specific steps include: S51. Calculate the effective temperature of each measuring point under the influence of real-time convection dissipation and lubricating medium fluid dynamic loss during the local test bench test under double-flow cooling medium The calculation formula is: ， wherein, in °C; S52. Set the cooling state of the lubricating oil under a standard state, so that the change of the cooling property of the lubricating oil and the influence of the fluid dynamic loss of the lubricating medium can be ignored, and therefore the above formula is simplified as: ， S53. Determine the effective temperature of each measuring point in the nominal state whether it is lower than the specified value required by the standard, and give the evaluation result.

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