Research Method for Thermal Field Characteristics in Lubricating Bearing Cavity under Roller Bearing Ring

Abstract

The present invention belongs to the technical field of bearing temperature field calculation, and particularly relates to a research method for the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring. An oil groove model of the bearing inner ring and a model of the bearing cavity are constructed; the oil supply amount and the bearing speed are changed. A certain oil supply amount and bearing speed are applied to the oil groove model of the bearing inner ring, and the frictional heat generation amount of the bearing is calculated by using the bearing speed. The frictional heat generation amount of the bearing is distributed to the heat generation amounts of the corresponding boundaries for simulation, so as to obtain the corresponding inlet flow rate and oil phase distribution data; the inlet flow rate and oil phase distribution data are applied to the bearing cavity model to conduct a thermal field simulation of the oil-gas two-phase flow in the bearing cavity, and various temperature rises in the bearing cavity are calculated to obtain the total temperature rise situation in the bearing cavity under different oil supply amounts and bearing speeds, so as to study the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring. Therefore, the problem that the characteristics of the thermal field in the prior art cannot accurately analyze the thermal field characteristics in the lubricating bearing cavity under the ring is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of bearing temperature field calculation, and particularly relates to a research method for the thermal field characteristics in the bearing cavity of a roller bearing with under-ring lubrication. Background Art

[0002] As a common standard mechanical part, high-speed cylindrical roller bearings are widely used in aero-engines. In recent years, with the increasing rotational speed of aero-engines, the thermal load of the internal bearings has become higher and higher, which poses new challenges to the lubrication method and lubrication efficiency of the bearings. Under-ring lubrication is a lubrication method that uses the centrifugal force during the operation of the bearing to throw lubricating oil into the bearing interior by opening holes in the inner ring of the bearing. Compared with the traditional oil injection lubrication method, the oil consumption is relatively less, the lubricating oil is more likely to reach the lubrication position, and the lubrication and cooling effects are better. When under-ring lubrication is used, the temperature in the bearing cavity is affected by various factors, such as the under-ring oil groove, rotational speed, oil supply amount, etc., and they will affect the lubrication efficiency of the bearing and the temperature during operation in different ways. Therefore, carrying out research on the thermal field characteristics of the oil-gas two-phase flow in the bearing cavity of a cylindrical roller bearing with under-ring lubrication to improve the lubrication efficiency of the main shaft bearing of an aero-engine and to reduce the bearing heating is an important research work.

[0003] However, current domestic and foreign research mainly focuses on the calculation and experiment of the internal flow field and thermal field of conventional lubrication methods such as oil-gas lubrication and oil injection lubrication, and the design and experiment of the under-ring oil supply channel, etc. However, these experimental methods are not completely applicable to under-ring lubrication, and it is impossible to realize the research on the thermal field characteristics in the bearing cavity of under-ring lubrication; moreover, the temperature distribution characteristics, influencing factors, and laws in the bearing cavity of under-ring lubrication bearings are not yet clear, and there is no effective method to realize the research on the thermal field characteristics in the bearing cavity of under-ring lubrication bearings, so it is impossible to accurately analyze its thermal field characteristics and provide effective guidance for the design of under-ring lubrication of high-speed cylindrical roller bearings. Summary of the Invention

[0004] The purpose of the present invention is to provide a research method for the thermal field characteristics in the bearing cavity of a roller bearing with under-ring lubrication, so as to solve the problem that the existing research methods cannot accurately analyze the thermal field characteristics in the bearing cavity of under-ring lubrication bearings.

[0005] To solve the above technical problems, the technical solutions provided by the present invention and the corresponding beneficial effects are as follows:

[0006] A research method for the thermal field characteristics in the bearing cavity of a roller bearing with under-ring lubrication of the present invention includes the following steps:

[0007] S1. Construct a bearing inner ring oil groove model with N cycle periods. The bearing inner ring oil groove model includes an oil inlet and an oil supply port. The boundary at the oil inlet is set as a pressure outlet, and the oil supply port of the bearing inner ring oil groove model is set as a velocity inlet. Construct a bearing cavity model with the same cycle angle as the bearing inner ring oil groove model, including an oil inlet. The oil inlet of the bearing cavity model corresponds to the oil inlet of the bearing inner ring oil groove model, and the oil inlet of the bearing cavity model is a velocity inlet. The cycle period is a single period of the periodic distribution of the oil groove.

[0008] S2. Apply a certain oil supply amount and bearing speed to the bearing inner ring oil groove model. Calculate the heat generated by friction of the bearing using the bearing speed, and distribute the heat generated by friction of the bearing to the heat generated at the corresponding boundary for simulation, so as to obtain the corresponding oil inlet flow rate and oil phase distribution data.

[0009] S3. Apply the oil inlet flow rate and oil phase distribution data to the bearing cavity model for thermal field simulation of the oil-gas two-phase flow in the bearing cavity, and calculate various temperature rises in the bearing cavity.

[0010] S4. Change the oil supply amount and / or bearing speed, and repeat steps S2 - S3 to obtain the total temperature rise situation in the bearing cavity under different oil supply amounts and bearing speeds, so as to study the thermal field characteristics of the lubricating bearing cavity under the roller bearing ring.

[0011] The beneficial effects of the above technical solutions are as follows: In the present invention, a bearing inner ring oil groove model and a bearing cavity model of a cylindrical roller bearing are established respectively. By changing the speed or oil supply amount respectively, a certain oil supply amount and bearing speed are applied to the bearing inner ring oil groove model. Calculate the heat generated by friction of the bearing using the bearing speed, and distribute the heat generated by friction of the bearing to the heat generated at the corresponding boundary for simulation to obtain the oil inlet flow rate and oil phase distribution data, and bring these data into the bearing cavity model for thermal field simulation of the oil-gas two-phase flow in the bearing cavity, and the temperature rise result in the bearing cavity will be obtained. The present invention calculates the influence of the speed and oil supply amount on the total temperature rise in the bearing cavity, and further analyzes the influence law of the bearing speed and oil supply amount on the temperature rise in the bearing cavity, reflecting the actual characteristics in the bearing cavity and having a simple model structure. Therefore, the present invention provides a reference basis for the lubrication design under the high-speed cylindrical roller bearing ring. On the other hand, since the present invention mainly obtains a more accurate oil inlet amount in the bearing cavity, the entire oil supply flow path of the lubrication under the ring is no longer modeled, and only the bearing inner ring oil groove is modeled and calculated, thus simplifying the model structure while ensuring the research effect.

[0012] Further, the various temperature rises include: total temperature rise, bearing friction temperature rise, and viscous shear temperature rise of the lubricating oil between the rings.

[0013] The beneficial effects of the above technical solution are as follows: The present invention calculates the effects of rotational speed and fuel supply on the total temperature rise in the bearing cavity, and separately calculates the bearing friction temperature rise and the viscous shear temperature rise of the lubricating oil between the rings, as well as the influence laws and degrees of the two on the total bearing temperature rise. The results show that when the bearing fuel supply is constant, the higher the bearing rotational speed, the more intense the friction of the internal components of the bearing, the greater the viscous shear force on the lubricating oil in the bearing cavity, and both the friction and viscous temperature rises increase; when the bearing rotational speed is constant, due to the increase in the viscous shear temperature rise of the lubricating oil caused by the increase in the oil volume and the improvement of the cooling effect, the former is higher than the latter when the oil volume is low, and then the two gradually level off. The viscous temperature rise first decreases and then remains at a certain level, and the bearing friction temperature rise decreases. This research provides a reference basis for the lubrication design under the ring of high-speed cylindrical roller bearings.

[0014] Further, the total temperature rise = the bearing friction temperature rise + the viscous shear temperature rise of the lubricating oil between the rings.

[0015] Further, the heat generated at the corresponding boundary in step S2 includes the heat generated separately distributed to the contact surfaces of the inner ring, outer ring and rollers of the bearing, and the frictional heat generated is distributed to the contact surfaces of the inner ring, outer ring and rollers of the bearing in a ratio of 1:1:2.

[0016] Further, N = 1; one cycle period is 48°, the bearing inner ring oil groove model includes 1 oil supply port and 2 oil inlet ports, and the bearing cavity model also takes 48° as a period.

[0017] Further, the number of degrees of the angle through which the oil inlet port completely passes through one rotation of the roller is recorded as one rotation period, and the corresponding range passed through is divided into multiple rotation ranges. A temperature measurement position is set in each rotation range, the temperature of the oil inlet port at each temperature measurement position is obtained, and finally the multiple obtained temperatures are weighted and averaged to obtain the temperature in the bearing cavity.

[0018] The beneficial effects of the above technical solution are as follows: For the bearing cavity fluid calculation model, since the relative position between the oil inlet port and the roller is constantly changing during under-ring lubrication, by calculating the temperatures at multiple different positions and weighting and averaging the obtained results as the final temperature result, more accurate temperature data can be obtained.

[0019] Further, the multiple rotation ranges are 3 rotation ranges, and the temperature T in the bearing cavity is:

[0020]

[0021] Among them, T1 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a1, T2 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a2, T3 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a3, a1, a2, and a3 are the angles corresponding to the three rotation ranges respectively, and A = a1 + a2 + a3.

[0022] Furthermore, during the simulation of the thermal field of the oil-gas two-phase flow in the bearing cavity, the contact surfaces of the bearing rollers and the inner and outer rings need to be set as heat sources, and corresponding convective heat transfer coefficients are set for the remaining walls.

[0023] Furthermore, boundary conditions need to be set before the simulation of the thermal field of the oil-gas two-phase flow in the bearing cavity; the boundary conditions include the boundary heat flux densities of the inner ring, outer ring, and rollers of the bearing; the inner ring heat flux density q i , the outer ring heat flux density q o , and the roller heat flux density q r can be obtained from the following formulas respectively:

[0024]

[0025]

[0026]

[0027] In the formulas: S i , S o , S r are the contact areas of the inner ring, outer ring, and rollers respectively, N is the frictional heat generation of the bearing, and C is the number of rollers.

[0028] Furthermore, the remaining walls of the oil groove model of the bearing inner ring are set as rotating walls, and the rotation speed of the rotating walls is the inner ring rotation speed; in the model of the bearing cavity, the outer ring is set as a stationary wall, the inner ring is set as a rotating wall, the rolling elements are set as rotating walls and their self-rotation is considered, and the cage is set as a rotating wall. Brief Description of the Drawings

[0029] Figure 1-1 is a schematic diagram of the modeling area of the inner ring oil groove in the method embodiment of the present invention;

[0030] Figure 1-2 is a three-dimensional perspective view of the modeling area of the inner ring oil groove in the method embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of the inner ring oil groove model in the method embodiment of the present invention;

[0032] Figure 3-1 is a three-dimensional schematic diagram of the model in the bearing cavity in the method embodiment of the present invention;

[0033] Figure 3-2 It is a schematic cross-sectional view of the model in the bearing cavity in the embodiment of the method of the present invention;

[0034] Figure 4 It is a schematic diagram of the calculation position in the embodiment of the method of the present invention;

[0035] Figure 5 It is a calculated contour map of the inner ring oil groove at different rotational speeds when the oil supply amount is 9.7 L / min in the embodiment of the method of the present invention;

[0036] Figure 6-1 It is a schematic diagram of the oil phase distribution of the inner and outer rings and rollers of the bearing under the oil supply amount of 5.7 L / min in the embodiment of the method of the present invention;

[0037] Figure 6-2 It is a schematic diagram of the oil phase distribution of the inner and outer rings and rollers of the bearing under the oil supply amount of 9.7 L / min in the embodiment of the method of the present invention;

[0038] Figure 6-3 It is a schematic diagram of the oil phase distribution of the inner and outer rings and rollers of the bearing under the oil supply amount of 13.7 L / min in the embodiment of the method of the present invention;

[0039] Figure 7-1 It is a streamline diagram of the lubricating oil temperature in the bearing cavity under the oil supply amount of 5.7 L / min in the embodiment of the method of the present invention;

[0040] Figure 7-2 It is a streamline diagram of the lubricating oil temperature in the bearing cavity under the oil supply amount of 9.7 L / min in the embodiment of the method of the present invention;

[0041] Figure 7-3 It is a streamline diagram of the lubricating oil temperature in the bearing cavity under the oil supply amount of 13.7 L / min in the embodiment of the method of the present invention;

[0042] Figure 8 It is a schematic diagram of the influence of the oil supply amount on the temperature rise in the bearing cavity in the embodiment of the method of the present invention;

[0043] Figure 9 It is a schematic diagram of the influence of the oil supply amount on the proportion of the viscous and frictional temperature rise in the total temperature rise in the embodiment of the method of the present invention;

[0044] Figure 10-1 It is a schematic diagram of the oil phase distribution of the inner and outer rings and rollers of the bearing at a rotational speed of 10000 r / min in the embodiment of the method of the present invention;

[0045] Figure 10-2 It is a schematic diagram of the oil phase distribution of the inner and outer rings and rollers of the bearing at a rotational speed of 14000 r / min in the embodiment of the method of the present invention;

[0046] Figure 10-3It is a schematic diagram of the oil phase distribution of the inner and outer rings and rollers of the bearing at a rotational speed of 18,000 r / min in the method embodiment of the present invention;

[0047] Figure 11 It is a schematic diagram of the influence of rotational speed on the temperature rise in the bearing cavity in the method embodiment of the present invention;

[0048] Figure 12 It is a schematic diagram of the influence of rotational speed on the proportion of viscous and frictional temperature rise in the total temperature rise in the method embodiment of the present invention.

[0049] In the figure: 1. Modeling area of the bearing cavity; 2. Modeling area of the oil groove on the inner ring of the bearing; 3. Roller; 4. Oil groove; 5. Outer ring; 6. Inner ring; 7. Inlet of the oil groove model on the inner ring of the bearing; 8. Oil supply port of the oil groove model on the inner ring of the bearing; 9. Periodic boundary; 101. First temperature measurement position; 102. Second temperature measurement position; 103. Third temperature measurement position; 11. Inlet of the model in the bearing cavity. Detailed implementation manners

[0050] Based on the data measured by experiments as boundary conditions, the present invention numerically simulates the temperature rise in the bearing cavity. Specifically, the present invention respectively establishes an oil groove model of the inner ring of a cylindrical roller bearing and an oil-gas two-phase flow model in the bearing cavity (bearing cavity model). The inlet flow rate and oil phase distribution are obtained through the oil groove model of the inner ring of the bearing, and these data are brought into the bearing cavity model for calculation. For the bearing cavity model, since the relative positions of the inlet and the rollers change continuously during under-ring lubrication, calculations are performed at multiple different positions, and the obtained results are weighted and averaged as the final result. The present invention calculates the influence of rotational speed and oil supply amount on the total temperature rise in the bearing cavity, and respectively calculates the bearing frictional temperature rise and the viscous shear temperature rise of the lubricating oil between the rings, as well as the influence laws and degrees of the two on the total temperature rise of the bearing.

[0051] The present invention will be described in detail below with reference to the embodiments.

[0052] Method embodiment:

[0053] First, the heat generation and heat transfer of the bearing in the simulation experiment of the present invention will be analyzed below.

[0054] 1. Calculation of bearing heat generation.

[0055] The calculation of bearing heat generation will be described below in combination with bearing heat generation.

[0056] The temperature rise of the bearing mainly comes from the heat generated by friction of the internal components of the bearing and the viscous shear heat generation of the lubricating oil between the rings. Without considering wear, for the frictional heat generation of the bearing, the overall method is adopted in the present invention for calculation. The overall method is derived by the Swedish engineer Palmgern based on a large amount of experimental data. The heat generation of the bearing is obtained by calculating the frictional torque of the entire bearing and multiplying it by the rotational speed. Table 1 shows the basic parameters of the cylindrical roller bearing.

[0057] Table 1 Basic parameters of cylindrical roller bearing

[0058] Parameter Value Outer diameter 194mm Inner diameter 144mm Number of rollers 30 Roller length 12mm Roller diameter 12mm

[0059] The calculation of the frictional heat generation of the bearing is as follows:

[0060] 1) Frictional torque generated by lubrication

[0061] When vn≥2000,

[0062] When vn≤2000,

[0063] In the formula: M0 is the frictional torque generated by lubrication, with the unit of N·mm; f0 is the coefficient related to the bearing lubrication method; v is the kinematic viscosity of the lubricating oil, with the unit of mm2 / s; D m is the pitch diameter of the bearing, with the unit of mm.

[0064] 2) Frictional torque generated by load

[0065] M1 = f1P1D m (3)

[0066] In the formula: f1 is the coefficient related to the bearing structure and the relative acting load of the bearing; P1 is the calculated load of the frictional torque.

[0067] The total frictional torque can be calculated as:

[0068] M = M0 + M1 (4)

[0069] The frictional heat generation of the bearing is:

[0070] N = 1.05×10 -4 nM (5)

[0071] In the formula: n is the rotational speed of the bearing, r / min.

[0072] When using FLUENT software to analyze the thermal field of the oil-gas two-phase flow in the bearing cavity, it is necessary to calculate the heat generation amount corresponding to the boundary. Since the overall method is adopted for heat generation calculation in this invention, the calculated frictional heat generation amount is distributed to the inner ring, outer ring, and roller contact surfaces with a relatively higher heat generation amount compared to other parts of the bearing at a ratio of 1:1, and then divided by the corresponding area to obtain. For parts with less heat generation, such as the friction between the cage and the roller and the friction between the cage and the inner and outer rings of the bearing, heat generation is not applied separately. The boundary heat flux density can be obtained from the following formula:

[0073]

[0074]

[0075]

[0076] In the formula: q i 、q o and q r are the heat flux densities of the inner ring, outer ring, and roller respectively; S i 、S o and S r are the contact areas of the inner ring, outer ring, and roller respectively, and C is the number of rollers.

[0077] Since the cylindrical roller bearing can only bear radial force, this invention calculates the heat generation state of the bearing at different rotational speeds when bearing a radial force of 5000 N, as shown in Table 2:

[0078] Table 2 Heat generation state of the bearing at different rotational speeds

[0079]

[0080] The following is an explanation in combination with the bearing heat transfer analysis.

[0081] 2. Bearing heat transfer analysis.

[0082] The temperature distribution in the flow field of the bearing cavity is uneven. According to the second law of thermodynamics, due to the existence of temperature difference, there must be heat transfer, and the temperature always transfers from the high-temperature object to the low-temperature object. The temperature transfer in the bearing cavity is mainly divided into three parts: thermal radiation, heat conduction, and heat convection. Since the distances between the components in the bearing cavity are very close, the heat transferred by thermal radiation can be ignored.

[0083] 1) Heat conduction:

[0084] In rolling bearings, heat conduction mainly occurs in each component of the bearing and between components. The heat conduction of rolling bearings satisfies Fourier's law, and the heat flux density q:

[0085]

[0086] Where: K is the thermal conductivity, with the unit of w / (m·K); is the temperature gradient.

[0087] 2) Heat convection:

[0088] When the rolling bearing is working, convective heat transfer mainly occurs between each component of the bearing and the air and lubricating oil in contact with it. The convective heat transfer coefficient between the bearing component and the lubricating oil in contact with it is:

[0089] α1 = 0.025Re 1 / 2 Pr 1 / 3 (10)

[0090] Where: Re is the Reynolds number of the lubricating oil; Pr is the Prandtl number of the lubricating oil.

[0091] The convective heat transfer coefficient between the bearing component and the surrounding air can be fitted with a polynomial:

[0092] α2 = 9.7 + 5.33u 0.8 (11)

[0093] Where: u is the rotational linear velocity, with the unit of m / s.

[0094] According to the boundary heat flux density, heat flux density, convective heat transfer coefficient between the bearing component and the surrounding air, and convective heat transfer coefficient between the bearing component and the lubricating oil in contact with it calculated above, the boundary conditions are set correspondingly in the fluent software. The heat flux density is the heat generation amount, which is applied to the contact surfaces of the rollers, inner and outer rings and the rollers; the convective heat transfer coefficient is applied to the contact part of the inner ring and the outside air.

[0095] The overall processing flow of the present invention is as follows: First, use solid works for modeling, and secondly, use space claim for pre-processing; then use fluent meshing to draw grids; finally, import into fluent for calculation.

[0096] The present invention will be described in detail below in conjunction with the attached drawings and steps.

[0097] S1. Construct an oil groove model of the bearing inner ring for N cycle periods. The oil groove model of the bearing inner ring includes the oil inlet 7 and the oil supply port 8 of the oil groove model of the bearing inner ring. The boundary at the oil inlet 7 of the oil groove model of the bearing inner ring is set as a pressure outlet, and the oil supply port 8 of the oil groove model of the bearing inner ring is set as a velocity inlet; construct a bearing cavity model with the same cycle angle as the oil groove model of the bearing inner ring, including the oil inlet 11 of the bearing cavity model. The oil inlet 11 of the bearing cavity model corresponds to the oil inlet 7 of the oil groove model of the bearing inner ring, and the oil inlet 11 of the bearing cavity model is a velocity inlet; the cycle period is a single period of the periodic distribution of the oil groove.

[0098] Specifically, for under-ring lubrication, the oil inflow at the under-ring oil inlet is determined by various factors and cannot be accurately controlled like in traditional lubrication methods. Therefore, it is very necessary to model the bearing oil supply channel to calculate the oil inflow at the under-ring oil inlet and the oil phase distribution under the action of centrifugal force. Since the present invention mainly aims to obtain a more accurate oil inflow in the bearing cavity, the entire oil supply channel for under-ring lubrication is not modeled, and only the oil groove on the inner ring of the bearing is modeled and calculated. The modeling region selected in the present invention includes the bearing cavity modeling region 1 and the inner ring oil groove modeling region 2 of the bearing, as follows Figure 1-1 , Figure 1-2 As shown, the present invention mainly analyzes the fluid domain in the bearing cavity and the inner ring oil groove. Therefore, the modeling region only includes the fluid domain and does not include the solid domain.

[0099] Since the oil grooves 4 are periodically distributed along the circumferential direction of the bearing, a single cycle is selected for modeling. The bearing contains 30 rollers and 15 oil inlets. Therefore, 4 rollers 3 and 2 oil supply ports are taken as a cycle. One cycle is 48°, and periodic boundary 9 is set for calculation. The model of the inner ring oil groove of the bearing is as follows Figure 2 As shown. The boundary at the oil inlet 7 of the inner ring oil groove model of the bearing is set as a pressure outlet and is kept continuous with the pressure in the bearing cavity; the oil supply port 8 of the inner ring oil groove model is set as a velocity inlet, and the oil supply is distributed periodically; the remaining walls are set as rotating walls, and their rotational speed is the rotational speed of the inner ring. The relevant calculation parameters are shown in Table 3.

[0100] Table 3 Calculation Parameters

[0101]

[0102] Correspondingly, the model in the bearing cavity also takes 48° as a cycle. Considering the complexity of the movement of the rotating components in the bearing, the multiple reference frame model is used for calculation. The model in the bearing cavity is as Figure 3-1 , Figure 3-2As shown, the oil inlet 11 of the model in the bearing cavity corresponds to the oil inlet 7 of the oil groove model of the bearing inner ring. The outer ring 5 is set as a stationary wall surface, the inner ring 6 is set as a rotating wall surface, the oil inlet 11 of the model in the bearing cavity is a velocity inlet, the rolling elements are set as rotating wall surfaces and their self-rotation is considered, the cage is a rotating wall surface, and the contact parts on both sides of the bearing cavity with the outside are set as pressure outlets. The contact surfaces between the rollers 3 and the inner and outer rings are respectively set as heat sources, and the corresponding convective heat transfer coefficients are set for the other wall surfaces. Regarding the relative position between the oil inlet 11 of the model in the bearing cavity and the roller 3 constantly changing during under-ring lubrication, considering the oil inlet 11 of the model in the bearing cavity completely passing by a roller as one rotation period, when the oil inlet 11 of the model in the bearing cavity completely passes by a roller 3, it rotates 12°. According to the relative position between the roller 3 and the oil inlet 11 of the model in the bearing cavity and the time required to pass through, this rotation period is divided into three parts (rotation ranges), which are 5°, 2°, and 5° respectively, as Figure 4 shown. A temperature measurement position is set for each part. The temperatures of the oil inlet 11 of the model in the bearing cavity at these three positions are calculated respectively. The three positions are the first temperature measurement position 101, the second temperature measurement position 102, and the third temperature measurement position 103. Finally, the three obtained temperatures are weighted and averaged to obtain the final temperature. The final temperature calculation expression is:

[0103]

[0104] In the formula: T is the temperature in the bearing cavity (final temperature), unit: K; T1 is the temperature at position 1, unit: K; T2 is the temperature at position 2, unit: K; T3 is the temperature at position 3, unit: K.

[0105] In summary, the number of degrees of rotation when the oil inlet 11 of the model in the bearing cavity completely passes by a roller 3 is recorded as one rotation period, and the corresponding passed range is divided into multiple rotation ranges. A temperature measurement position is set within each rotation range, the temperature of the oil inlet at each temperature measurement position is obtained, and finally the multiple obtained temperatures are weighted and averaged to obtain the temperature in the bearing cavity. In other embodiments, this rotation period can also be divided into three parts such as 4°, 4°, 4° or 4°, 5°, 3° respectively. In short, there are 3 measurement positions, and the temperature T in the bearing cavity is:

[0106]

[0107] Among them, T1 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a1, T2 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a2, T3 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a3, a1, a2, and a3 are the angles corresponding to the 3 rotation ranges respectively, and A = a1 + a2 + a3.

[0108] In other embodiments, according to the relative positions of the rollers and the oil supply ports and the time required, this rotation period can also be divided into four parts, and 4 measurement positions are set. The temperature T in the bearing cavity is as follows:

[0109]

[0110] Wherein, T1 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a1, T2 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a2, T3 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a3, T4 is the temperature obtained at the temperature measurement position set within the rotation range corresponding to a4, a1, a2, a3, and a4 are the angles corresponding to the 4 rotation ranges respectively, and A = a1 + a2 + a3 + a4.

[0111] S2. Apply a certain oil supply amount and bearing speed to the oil groove model of the bearing inner ring, calculate the frictional heat generation of the bearing using the bearing speed, and distribute the frictional heat generation of the bearing to the heat generation of the corresponding boundary for simulation, so as to obtain the corresponding inlet flow rate and oil phase distribution data; change the oil supply amount or the bearing speed, repeat the simulation experiment, and obtain different inlet flow rates and oil phase distribution data.

[0112] Figure 5 Figure 13 is the calculation nephogram of the inner ring oil groove at different speeds when the oil supply amount is 9.7 L / min. Table 4 shows the oil phase distribution (oil phase volume fraction) and oil flow velocity of oil supply ports 1 and 2 after conversion. Table 5 shows the oil phase distribution and oil flow velocity of oil supply ports 1 and 2 at different oil supply amounts when the speed is 14000 r / min. As the speed increases, the lubricating oil distribution in the inner ring oil groove becomes more uneven, and the lubricating oil becomes more concentrated on one side of the oil supply port. This phenomenon is improved with the increase of the oil supply amount. This is because due to inertia, the rotation of the lubricating oil lags behind the rotation of the inner ring. When the inner ring speed is faster, this lag is more obvious, resulting in the lubricating oil concentrating on one side of the oil supply port. And when the speed is faster, the thrust of the inner ring oil groove wall on the lubricating oil is also greater. Therefore, the lubricating oil will quickly flow out from the oil supply port closer to the direction opposite to the rotation of the inner ring. And due to the existence of the unilateral circumferential oil groove, the flow direction of the lubricating oil is more inclined to be close to the oil supply port of the unilateral circumferential oil groove, thus causing this phenomenon. However, the flow rate of one oil supply port is limited. When the oil supply amount increases, more oil will flow to the next oil supply port, thereby improving this phenomenon.

[0113] Table 4 Oil flow velocity and oil phase table of oil supply ports when the oil supply amount is 9.7 L / min

[0114]

[0115]

[0116] Table 5 Flow velocity at the oil supply port and oil phase table at a rotational speed of 14,000 r / min

[0117]

[0118] S3. Apply the inlet oil flow rate and oil phase distribution data to the model in the bearing cavity to conduct a thermal field simulation of the oil-gas two-phase flow in the bearing cavity, and calculate various temperature rises in the bearing cavity.

[0119] S4. Use the inlet oil flow rate and oil phase distribution data at different oil supply amounts and different bearing rotational speeds in S2, repeat step S3, and obtain the total temperature rise conditions in the bearing cavity at different oil supply amounts and bearing rotational speeds, so as to study the thermal field characteristics in the lubricated bearing cavity under the roller bearing ring.

[0120] Take the temperature measured under the current experimental conditions as the boundary condition. According to the calculated flow velocity and oil phase at the oil supply port obtained from the inner ring oil groove, apply them to the model in the bearing cavity, and calculate the total temperature rise, frictional temperature rise, and viscous shear temperature rise of the lubricating oil of the bearing at different rotational speeds and different oil supply amounts. Total temperature rise = bearing frictional temperature rise + viscous shear temperature rise of the lubricating oil between the rings; Bearing frictional temperature rise: obtained by subtracting the model without applying frictional heat and viscous heat from the model with applied frictional heat and without applied viscous heat; Viscous shear temperature rise of the lubricating oil between the rings: obtained by subtracting the model with applied frictional heat and without applied viscous heat from the model with applied frictional heat and applied viscous heat.

[0121] The oil phase distributions of the inner and outer rings and rollers of the bearing at different oil supply amounts when the rotational speed is 14,000 r / min are as Figure 6-1 、 Figure 6-2 、 Figure 6-3 shown. The left scale represents the oil phase volume fraction. To more easily see the situation in the bearing cavity, only partial oil phase distributions of the inner and outer rings and rollers are shown in the contour map. When the oil supply amount is at a low level, the oil fluid distributions at the two inlet oil ports are uneven, resulting in uneven distribution of the lubricating oil in the bearing cavity and aggregation on one side. This phenomenon improves with the increase in the oil supply amount, and with the increase in the oil supply amount, the lubricating oil is more likely to reach the lubrication position. When the oil supply amount is above 9.7 L / min, there is already a certain amount of lubricating oil distributed at the lubrication position of the bearing. The temperature streamline diagram of the lubricating oil in the bearing cavity is as Figure 7-1 、 Figure 7-2 、 Figure 7-3 shown. When the oil supply amount is lower than 9.7 L / min, with the increase in the oil supply amount, the oil fluid streamlines in the bearing cavity are significantly changed from sparse to dense, the oil fluid volume fraction in the bearing cavity is significantly increased, and the temperature is significantly decreased; when it is above 9.7 L / min, the oil fluid volume fraction in the bearing cavity does not increase significantly, and the temperature does not decrease significantly, indicating that increasing the oil supply amount after the ring-under lubrication oil supply amount reaches a certain level cannot significantly improve the lubrication and cooling performance of the bearing. From Figure 7-1 、 Figure 7-2 、Figure 7-3 It can be seen that when the fuel supply is low, for the heat generation due to viscous shearing of the lubricating oil, the areas with higher lubricating oil temperatures are mainly distributed in the areas with less oil around the rollers. This is because the lubricating oil flow rate around the rollers is higher, and the viscous shear force on the lubricating oil is greater. With the improvement of the cooling effect brought about by the increase in the oil volume, these high-temperature areas gradually decrease.

[0122] The influence of the fuel supply on the temperature rise in the bearing cavity when the rotational speed is 14,000 r / min is as Figure 8 . With the increase in the fuel supply, the cooling effect improves, and the total temperature rise in the bearing cavity decreases; with the rotational speed remaining unchanged, the heat generated by bearing friction remains unchanged. Since increasing the fuel supply above 9.7 L / min has little effect on improving the cooling effect of the bearing, the frictional temperature rise decreases and the decreasing speed becomes slower; the viscous shear temperature rise of the lubricating oil first decreases and then remains at a certain level; this is because when the fuel supply is at a low level, the viscous temperature rise caused by the shear force on the lubricating oil is the main factor, and when the fuel supply gradually increases, the two gradually balance out.

[0123] The ratio between the viscous shear temperature rise and the frictional temperature rise of the lubricating oil is as Figure 9 shown. For the total temperature rise, the viscous shear temperature rise of the lubricating oil still accounts for the main part. Since the viscous shear temperature rise of the lubricating oil remains at a certain level with the increase in the fuel supply, the frictional temperature rise decreases and the decreasing speed slows down, and the proportions of the two in the total temperature rise gradually tend to a fixed value.

[0124] The oil phase distributions of the inner and outer rings and the rollers of the bearing at different rotational speeds when the fuel supply is 9.7 L / min are as Figure 10-1 , Figure 10-2 and Figure 10-3 shown. When the fuel supply is constant, with the increase in the rotational speed, the airflow movement in the bearing cavity intensifies, the pressure distribution is uneven, and coupled with the influence of the roller rotation on the lubricating oil, it becomes more difficult for the lubricating oil to reach the lubrication positions. The influence of the rotational speed on the temperature rise in the bearing cavity when the fuel supply is 9.7 L / min is as Figure 11 . With the increase in the rotational speed, the lubricating oil attached to the outer ring and the roller surfaces gradually decreases, the lubrication and cooling effects decrease, so the frictional temperature rise increases. In addition, the increase in the rotational speed makes the viscous shear force on the lubricating oil increase, the viscous shear heat generation of the lubricating oil increases, and the corresponding total temperature rise increases.

[0125] For the total temperature rise, the proportion of the viscous shear temperature rise of the lubricating oil is greater than that of the frictional temperature rise, as Figure 12 shown, and this proportion becomes larger and larger with the increase in the rotational speed. Combining Figure 10-1 , Figure 10-2 and Figure 10-3It can be seen that this is because as the rotational speed increases, it becomes more difficult for the lubricating oil to reach the lubrication positions, the lubricating oil at the contact positions between the rollers and the inner and outer rings decreases, and the cooling effect is reduced. Combining with the conclusion obtained from the previous text that when the oil volume is at a low level, the viscous temperature rise caused by the shear force of the lubricating oil is the main factor while the temperature drop caused by the cooling of the lubricating oil is secondary, it can be known that the viscous shear temperature rise of the lubricating oil increases faster.

[0126] The following conclusions can be obtained through the thermal analysis of the inner ring oil groove and cavity model of the under-ring lubricated cylindrical roller bearing:

[0127] (1) The lubricating oil flow rates at the under-ring oil supply ports on both sides of the under-ring lubricated cylindrical roller bearing are uneven. When the oil supply amount is fixed, the higher the rotational speed, the more uneven the distribution. Moreover, when the flow rate at the oil supply port is uneven, the oil phase distribution at the corresponding positions in the bearing cavity is also uneven, and this phenomenon improves with the increase in the oil supply amount.

[0128] (2) When the oil supply amount of the bearing is fixed, as the rotational speed increases, it is difficult for the lubricating oil to reach the lubrication positions, and the total temperature rise in the bearing cavity increases; when the rotational speed of the bearing is fixed, when the oil supply amount is below 9.7 L / min, as the oil supply amount increases, the oil volume fraction in the bearing cavity increases rapidly and the total temperature rise decreases significantly. When the oil supply amount is above 9.7 L / min, as the oil supply amount increases, the increase in the oil volume fraction in the bearing cavity slows down and the decrease in the total temperature rise slows down.

[0129] (3) The total temperature rise in the bearing cavity is affected by the frictional temperature rise and the viscous shear temperature rise of the lubricating oil. When the oil supply amount is fixed, both the frictional temperature rise and the viscous temperature rise increase with the increase in the rotational speed; when the rotational speed is fixed, the frictional temperature rise decreases with the increase in the oil supply amount, and the viscous temperature rise first decreases and then remains at a certain level.

[0130] (4) Among the total temperature rise in the bearing cavity, the viscous shear temperature rise of the lubricating oil accounts for the main part, and the proportion of the viscous temperature rise in the total temperature rise increases with the increase in the rotational speed and the oil supply amount, while the frictional temperature rise is the opposite.

[0131] In the present invention, an oil groove model of the inner ring of a cylindrical roller bearing and a model of the bearing cavity are respectively established. By changing the rotational speed or the oil supply amount separately, a certain oil supply amount and a bearing rotational speed are applied to the oil groove model of the bearing inner ring. The frictional heat generation of the bearing is calculated using the bearing rotational speed, and the frictional heat generation of the bearing is distributed to the heat generation of the corresponding boundary for simulation to obtain the oil inlet flow rate and oil phase distribution data. These data are then brought into the bearing cavity model for thermal field simulation of the oil-gas two-phase flow in the bearing cavity, and the temperature rise result in the bearing cavity is obtained. The present invention calculates the influence of the rotational speed and the oil supply amount on the total temperature rise in the bearing cavity, and further analyzes the influence law of the bearing rotational speed and the oil supply amount on the temperature rise in the bearing cavity, reflecting the actual characteristics in the bearing cavity and having a simple model structure. Therefore, the present invention provides a reference basis for the lubrication design under the ring of high-speed cylindrical roller bearings. On the other hand, since the present invention mainly aims to obtain a relatively accurate oil inlet amount in the bearing cavity, the entire oil supply flow path of the lubrication under the ring is not modeled, and only the oil groove of the bearing inner ring is modeled and calculated, thereby simplifying the model structure while ensuring the research effect. Since it is difficult to measure the temperature in the bearing cavity experimentally, the present invention performs a numerical simulation of the temperature rise in the bearing cavity using the data that can be measured experimentally as boundary conditions, which has great reference value.

Claims

1. A research method for the thermal field characteristics in the lubricating bearing cavity under a roller bearing ring, characterized in that: It includes the following steps: S1. Construct a bearing inner ring oil groove model with N cycle periods. The bearing inner ring oil groove model includes an oil inlet and an oil supply port. The boundary at the oil inlet of the bearing inner ring oil groove model is set as a pressure outlet, and the oil supply port of the bearing inner ring oil groove model is set as a velocity inlet; construct a bearing cavity model with the same cycle period angle as the bearing inner ring oil groove model. The bearing cavity model includes an oil inlet, and the oil inlet of the bearing cavity model corresponds to the oil inlet of the bearing inner ring oil groove model. The oil inlet of the bearing cavity model is a velocity inlet; the cycle period is a single period of the periodic distribution of the oil groove. S2. Apply a certain oil supply amount and bearing speed to the bearing inner ring oil groove model, calculate the heat generated by friction of the bearing using the bearing speed, and distribute the heat generated by friction of the bearing to the heat generated on the contact surfaces of the bearing inner ring, outer ring, and rollers corresponding to the boundaries for simulation, so as to obtain the corresponding oil inlet flow rate and oil phase distribution data. S3. Apply the oil inlet flow rate and oil phase distribution data to the bearing cavity model for thermal field simulation of the oil-gas two-phase flow in the bearing cavity, and calculate various temperature rises in the bearing cavity including the total temperature rise, bearing friction temperature rise, and viscous shear temperature rise of the lubricating oil between rings; moreover, record the number of degrees of the angle that the oil inlet completely passes through during one rotation of a roller as one rotation period, and divide the corresponding range into multiple rotation ranges. Set a temperature measurement position in each rotation range, obtain the temperature of the oil inlet at each temperature measurement position, and finally perform a weighted average on the obtained multiple temperatures to obtain the temperature in the bearing cavity. S4. Change the oil supply amount and / or bearing speed, repeat steps S2 to S3, and obtain the total temperature rise situation in the bearing cavity under different oil supply amounts and bearing speeds to study the thermal field characteristics of the lubricating bearing cavity under the roller bearing ring.

2. The research method for the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring according to claim 1, characterized in that: The total temperature rise = the bearing friction temperature rise + the viscous shear temperature rise of the lubricating oil between rings.

3. The research method for the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring according to claim 1, wherein: Distribute the heat generated by friction in a ratio of 1:1:2 to the contact surfaces of the bearing inner ring, outer ring, and rollers.

4. The research method for the thermal field characteristics in the lubrication bearing cavity under the roller bearing ring according to claim 1, characterized in that: N = 1; one cycle period is 48°, the bearing inner ring oil groove model includes 1 oil supply port and 2 oil inlets, and the bearing cavity model also takes 48° as one period.

5. The research method for the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring according to claim 1, wherein: The multiple rotation ranges are 3 rotation ranges, and the temperature T in the bearing cavity is: T= Wherein, T1 is the temperature obtained at the temperature measurement position set in the rotation range corresponding to a1, T2 is the temperature obtained at the temperature measurement position set in the rotation range corresponding to a2, T3 is the temperature obtained at the temperature measurement position set in the rotation range corresponding to a3, a1, a2, and a3 are the angles corresponding to the 3 rotation ranges respectively, and A = a1 + a2 + a3.

6. The research method for the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring according to claim 1, characterized in that: During the process of simulating the thermal field of the oil-gas two-phase flow in the bearing cavity, it is necessary to set the contact surfaces of the bearing rollers and the inner and outer rings as heat sources, and set the corresponding convective heat transfer coefficients for the remaining walls.

7. The research method for the thermal field characteristics in the lubricating bearing cavity under the roller bearing ring according to any one of claims 1-6, characterized in that: Before conducting thermal field simulation of oil-gas two-phase flow in the bearing cavity, boundary conditions need to be set; the boundary conditions include the boundary heat flux density of the bearing inner ring, outer ring and roller; the heat flux density of the inner ring q i , outer ring heat flux density q o , roller heat flux q r They can be derived from the following formulas: q i = q o = q r = Where: S i , S o , S r are the contact areas of the inner ring, outer ring, and rollers respectively, N is the heat generated by friction of the bearing, and C is the number of rollers.

8. The research method for the thermal field characteristics in the lubrication bearing cavity under the roller bearing ring according to any one of claims 1-6, characterized in that: The remaining walls of the bearing inner ring oil groove model are set as rotating walls, and the rotation speed of the rotating walls is the inner ring speed. In the bearing cavity model, the outer ring is set as a stationary wall, the inner ring is set as a rotating wall, the rolling elements are set as rotating walls and their self-rotation is considered, and the cage is set as a rotating wall.

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