Direct drive wind turbine three-row roller type slewing bearing and design method

Abstract

The application discloses a three-row roller type rotary disc bearing of a direct drive type wind turbine generator unit and a design method, and belongs to the technical field of wind turbine bearings. The rotary disc bearing adopts a three-row point contact structure of one row of radial spherical rollers and two rows of axial thrust ball rollers. The radial spherical rollers bear radial loads, and the two rows of axial thrust ball rollers jointly bear axial loads and overturning moments. Each row of rollers can be arranged in a single row or multiple rows in parallel. The application establishes an integrated design system including static strength checking, working contact angle solving and fatigue life prediction. A contact stress calculation model is established based on Hertz point contact theory. Dynamic contact angle distribution is solved by combining deformation geometric relationship under combined loads, and life evaluation is completed. The application can effectively reduce bearing sliding friction and edge stress concentration, improve operation stability and service life, and is suitable for high-power direct drive wind turbine generator unit main bearing scenes.

Description

Technical Field

[0001] This invention discloses a three-row roller turntable bearing for direct-drive wind turbine generator sets and its design method, relating to the field of wind turbine generator bearing technology. Background Technology

[0002] Three-row cylindrical roller bearings, as one of the main structural types of wind turbine generator main bearings, have the advantages of relatively simple processing and manufacturing and high load-bearing capacity. Their core structure and working method are as follows: they consist of an outer ring, an inner ring, and three rows of cylindrical rollers. The outer ring is connected to the motor rotor, and the inner ring is fixed to the motor stator / frame. The three rows of cylindrical rollers are divided into two rows of axial rollers and one row of radial rollers, forming three independent raceway systems, which respectively bear axial loads, overturning moments, and radial loads. The core purpose of this structural design is to bear the combined loads such as radial loads, axial loads, and overturning moments generated during the operation of the unit through the synergistic action of multiple rows of rollers, ensuring the stable operation of the transmission system. Line contact fit endows bearings with high rated dynamic and static load carrying capacity, but the contact stress is Gaussian distributed along the contact line, which easily forms stress concentration areas at the roller ends and raceway edges, inducing contact fatigue failure modes such as raceway surface peeling and roller wear. At the same time, the sliding friction component between the roller and the raceway is high in the line contact state, and it is highly dependent on the viscosity and extreme pressure performance of the lubricating medium. The failure of the lubrication system will directly lead to an aggravation of the temperature rise of the bearing friction pair, thereby causing nonlinear decay of bearing life. Summary of the Invention

[0003] This invention addresses the problems in the prior art by providing a three-row roller turntable bearing for direct-drive wind turbine generator sets and its design method. The proposed integrated design method for static strength and fatigue life establishes a dedicated stress calculation and life prediction model for the improved roller structure, which can accurately guide the optimization of bearing parameters and ensure that the improved bearing achieves the optimal balance between performance, reliability and economy.

[0004] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A three-row roller slewing bearing for a direct-drive wind turbine generator set includes an inner ring, an outer ring, and three rows of rolling elements disposed between the inner and outer rings. The three rows of rolling elements consist of one row of radial spherical rollers and two rows of axial thrust spherical rollers, wherein each row contains one or more rows of spherical roller structures. The one row of radial spherical rollers is used to bear radial loads, and the two rows of axial thrust spherical rollers are used to bear axial loads and overturning moments simultaneously.

[0005] The design method for three-row roller slewing bearings in direct-drive wind turbine generators includes static strength design, bearing working contact angle design, and fatigue life design. Static strength design involves establishing a ball-roller-raceway contact stress calculation model based on Hertzian point contact theory, solving for the maximum Hertzian contact stress at the contact point, and verifying the static strength safety factor in conjunction with the contact fatigue limit strength of the bearing material. Bearing working contact angle design involves determining the contact angle at any position of the bearing based on the deformation geometry of the bearing under combined loads. Fatigue life design involves calculating the reference rated life of the bearing based on its rated dynamic load and equivalent dynamic load, combined with a life correction factor.

[0006] Preferably, the static strength design includes: calculating the first maximum Hertz contact stress between the radial spherical roller and the raceway, and the second maximum Hertz contact stress between the axial thrust spherical roller and the raceway; calculating the static strength safety factor of the radial raceway based on the first maximum Hertz contact stress and the Vickers hardness of the raceway surface; and calculating the static strength safety factor of the axial raceway based on the second maximum Hertz contact stress and the Vickers hardness of the raceway surface.

[0007] Preferably, the calculation formulas for the first maximum Hertz contact stress between the radial spherical roller and the raceway and the second maximum Hertz contact stress between the axial thrust spherical roller and the raceway are both: ; ; ; in, Equivalent elastic modulus E 1 and E 2 represents the elastic modulus of the roller and raceway, respectively. n 1 and n 2 represents the Poisson's ratio of the roller and the raceway, respectively; , Let be the algebraic sum of the principal curvatures of the contact surfaces between the roller and the raceway; Q The normal force between the roller and the raceway; This is a complete elliptic integral of the second kind. e Let be the eccentricity of the ellipse.

[0008] Preferably, the first maximum Hertz contact stress is calculated separately. q rmax Second maximum Hertz contact stress q amax Substitute into the following formulas respectively q max In the calculation, the static strength safety factors for the radial raceway and the axial raceway are respectively calculated as follows: S r andS a : ; in, HV The Vickers hardness of the raceway surface, [ q [This represents the allowable Hertz contact stress for static strength.] q max This is the maximum pressure on the contact surface between the roller and the raceway.

[0009] Preferably, the geometric relationship after contact deformation is as follows: ; in, For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the inner and outer groove curvature coefficients, D. w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

[0010] Preferred, in The contact angle is largest at [location name], at [location name]. The contact angle is smallest at this location: ; ; in, For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the inner and outer groove curvature coefficients, D. w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing. Preferably, the bearing reference rated life L 10r Represented as: ; in, a isor This is the life correction factor for radial spherical rollers. Q rci The rated dynamic load for the radial spherical roller inner ring, Q rei The equivalent dynamic load on the radial spherical roller inner ring is...Q rce The rated dynamic load for the radial spherical roller outer ring, Q ree Equivalent dynamic load on the radial spherical roller outer ring; a isoa This is the life correction factor for axial thrust ball rollers. Q aci This represents the basic rated dynamic load between the inner ring and the rollers of an axial thrust ball roller bearing. Q ace This represents the basic rated dynamic load between the outer ring and rollers of an axial thrust ball roller bearing. Q aei For the first m Equivalent dynamic load between the inner ring and rollers of an axial thrust ball roller bearing. Q aee For the first m Equivalent dynamic load between the outer ring and rollers of an axial thrust ball roller bearing.

[0011] Preferably, the point contact load between the raceway and the ball roller is: ; in, K n The coefficients related to Hertzian contact. For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. D w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

[0012] Preferably, the simplified basic radial dynamic load rating of the bearing is calculated using the following formula: ; in, i For the number of columns of the rolling body, α The nominal contact angle of the bearing. Z For the number of single-column scroll bodies, D w The diameter of the rolling element, f c The following formula is used for calculation: ; in, l The reduction factor related to the quality of bearing manufacturing and installation. ,andD w The diameter of the rolling element, α The nominal contact angle of the bearing. d m The bearing pitch circle diameter, , These are the inner and outer raceway groove curvature radii, respectively. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively.

[0013] Preferably, according to the ISO / TS 16281 standard, the basic rated dynamic load between the inner ring, outer ring, and rollers of a radial spherical roller bearing is: ; ; in, C r This represents the basic radial dynamic load rating of the bearing. i For the number of rollers, Z The number of scroll bodies per column, α The nominal contact angle of the bearing. r i , r e These are the inner and outer raceway groove curvature radii, respectively. D w The diameter of the rolling element, , d m This is the diameter of the bearing pitch circle.

[0014] Preferably, the basic rated dynamic load of the bearing axial direction is calculated using the following formula: ; ; in, , D w The diameter of the rolling element, d m The diameter of the roller pitch circle. α The nominal contact angle of the bearing. Z The number of scroll bodies per column, l , or This is the bearing correction factor. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. F(D w ) This is a correction function whose value is determined by the roller diameter: ; The rated dynamic load for a thrust ball bearing with multiple rows of rollers is: ; in, i For the number of columns of the rolling body, C aj For the first j Axial dynamic load rating of rolling element ball bearings Z j The number of scroll elements in column j.

[0015] Preferably, the basic rated dynamic load between the inner ring, outer ring, and rollers of the axial thrust ball roller bearing is: ; ; in, C aD This represents the basic axial dynamic load rating of the bearing. Z The number of rollers per column, α The nominal contact angle of the bearing. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. r i , r e These are the inner and outer raceway groove curvature radii, respectively. D w The diameter of the rolling element.

[0016] Preferably, when the outer ring is fixed and the inner ring rotates relative to the load, the equivalent dynamic load between the inner ring, the outer ring, and the rollers is: ; in, Z The number of rollers per column, For the first j The load of each roller, F It can be a radial load or an axial load. Preferably, the raceway life correction factor for axial thrust ball roller bearings is defined according to ISO 281 and ISO / TS 16281 standards. a isoa The calculation formula is: ; Radial spherical roller bearing raceway life correction factor a isor The calculation formula is: ; in, kThis refers to the viscosity ratio of the lubricant. e c As a lubricant contaminant, C u For fatigue load life, P This is the equivalent dynamic load of the raceway.

[0017] The beneficial effects of this invention are: The direct-drive wind turbine generator set three-row roller slewing bearing provided by this invention adopts a point contact fit scheme, which changes the contact form between the roller and the inner and outer raceways from line contact to point contact; each row of ball rollers is evenly distributed in several rows along the circumferential direction, fundamentally changing the stress transmission path and mechanical response characteristics of the bearing friction pair, and reducing the wear and friction power consumption between the roller and the raceway.

[0018] II. The direct-drive wind turbine generator set three-row roller slewing bearing provided by this invention features optimized tribological performance: the point contact mating mode significantly reduces the sliding friction component between the rollers and raceways, resulting in a significant reduction in the bearing friction coefficient; under the same lubrication conditions, the temperature rise of the bearing friction pair is effectively controlled, improving the bearing operational stability of megawatt-level wind turbine generators under high-speed and high-load conditions, and reducing the frequency of lubrication maintenance. The contact stress field is homogenized: the point contact characteristics transform the contact stress from a Gaussian distribution of line contact to a hemispherical distribution of point contact, significantly reducing the stress concentration factor and drastically decreasing the peak stress at the roller edges. This mitigates the risk of failure such as raceway surface spalling and roller wear, resulting in a significant improvement in bearing fatigue life.

[0019] III. The design method of the three-row roller turntable bearing for direct-drive wind turbine generator provided by this invention constructs a ball-roller-raceway contact stress calculation model based on Hertzian point contact theory, solves the maximum contact stress at the contact point, completes static strength verification by combining the contact fatigue limit strength of the bearing material, and completes the bearing working contact angle design. At the same time, it combines fatigue life calculation and couples the influence of roller structure parameters on load distribution to improve the accuracy and reliability of bearing fatigue life prediction.

[0020] IV. The design method for the three-row roller slewing bearing of the direct-drive wind turbine generator set provided by this invention has a complete integrated design system and strong engineering applicability: it constructs a full-process design method that couples static strength verification, working contact angle solution and fatigue life prediction, and fully considers the dynamic influence of raceway elastic deformation on contact angle distribution under combined load, thus overcoming the limitations of traditional design methods that simplify the constant contact angle and have insufficient accuracy in load distribution calculation; the design model is adapted and modified for the service characteristics of low-speed heavy load and alternating load of the main bearing of the direct-drive wind turbine, and can efficiently support multi-objective optimization of core parameters such as roller diameter, groove curvature coefficient and raceway layout, quickly match the load requirements of units of different power levels, and effectively reduce product development cycle and test verification costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the radial cross-section of the bearing in this invention; Figure 2 This is a schematic diagram of the contact angle variation in this invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0023] Example 1 like Figure 1 As shown, the three-row roller slewing bearing of the direct-drive wind turbine generator set includes one row of radial spherical rollers and two rows of axial thrust spherical rollers, wherein each row contains one or more rows of spherical roller structures. The one row of radial spherical rollers is used to bear radial loads simultaneously, and the two rows of axial thrust spherical rollers are used to bear axial loads and overturning moments.

[0024] Example 2 The design method of the three-row roller slewing bearing for the direct-drive wind turbine generator set in Example 1 includes static strength design, bearing working contact angle design, and fatigue life design. Static strength design: Based on Hertzian point contact theory, a ball-roller-raceway contact stress calculation model is established to solve for the maximum Hertzian contact stress at the contact point, and the static strength safety factor is checked in conjunction with the contact fatigue limit strength of the bearing material. Bearing working contact angle design: Based on the deformation geometry of the bearing under combined load, the contact angle at any position of the bearing is determined. Fatigue life design: Based on the rated dynamic load and equivalent dynamic load of the bearing, the reference rated life of the bearing is calculated in conjunction with the life correction factor.

[0025] The static strength design includes: calculating the first maximum Hertz contact stress between the radial spherical roller and the raceway, and the second maximum Hertz contact stress between the axial thrust spherical roller and the raceway; calculating the static strength safety factor of the radial raceway based on the first maximum Hertz contact stress and the Vickers hardness of the raceway surface; and calculating the static strength safety factor of the axial raceway based on the second maximum Hertz contact stress and the Vickers hardness of the raceway surface.

[0026] According to Hertz point contact theory, the formulas for calculating the first maximum Hertz contact stress between the radial spherical roller and the raceway and the second maximum Hertz contact stress between the axial thrust spherical roller and the raceway are as follows: ; ; ; in, Equivalent elastic modulusE 1 and E 2 represents the elastic modulus of the roller and raceway, respectively. n 1 and n 2 represents the Poisson's ratio of the roller and the raceway, respectively; , Let be the algebraic sum of the principal curvatures of the contact surfaces between the roller and the raceway; Q The normal force between the roller and the raceway; This is a complete elliptic integral of the second kind. e Let be the eccentricity of the ellipse.

[0027] Among them, the first maximum Hertz contact stress will be calculated separately. q rmax Second maximum Hertz contact stress q amax Substitute into the following formulas respectively q max In the calculation, the static strength safety factors for the radial raceway and the axial raceway are respectively calculated as follows: S r and S a : ; in, HV The Vickers hardness of the raceway surface, [ q [This represents the allowable Hertz contact stress for static strength.] q max This is the maximum pressure on the contact surface between the roller and the raceway.

[0028] In particular, considering the low rotational speed of direct-drive wind turbines and the fact that the bearings are simultaneously subjected to combined axial and radial loads, the contact angle of each ball varies under these conditions. Figure 2 As shown, the geometric relationship after contact deformation is as follows: ; in, For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the inner and outer groove curvature coefficients, D. w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

[0029] From the above formulas and the geometric relationships in the figure, the formula for calculating the contact angle at any position of the bearing can be derived as follows: The contact angle is largest at [location name], at [location name]. The contact angle is smallest at this location: ; ; in, For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the inner and outer groove curvature coefficients, D. w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing. Among them, the bearing reference rated life L 10r Represented as: ; in, a isor This is the life correction factor for radial spherical rollers. Q rci The rated dynamic load for the radial spherical roller inner ring, Q rei The equivalent dynamic load on the radial spherical roller inner ring is... Q rce The rated dynamic load for the radial spherical roller outer ring, Q ree Equivalent dynamic load on the radial spherical roller outer ring; a isoa This is the life correction factor for axial thrust ball rollers. Q aci This represents the basic rated dynamic load between the inner ring and the rollers of an axial thrust ball roller bearing. Q ace This represents the basic rated dynamic load between the outer ring and rollers of an axial thrust ball roller bearing. Q aei For the first m Equivalent dynamic load between the inner ring and rollers of an axial thrust ball roller bearing. Q aee For the first m Equivalent dynamic load between the outer ring and rollers of an axial thrust ball roller bearing.

[0030] The point contact load between the raceway and the ball roller is: ; in, K n The coefficients related to Hertzian contact. For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. D w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

[0031] The simplified basic radial dynamic load rating of the bearing is calculated using the following formula: ; in, i For the number of columns of the rolling body, α The nominal contact angle of the bearing. Z For the number of single-column scroll bodies, D w The diameter of the rolling element, f c The following formula is used for calculation: ; in, l The reduction factor related to the quality of bearing manufacturing and installation. ,and D w The diameter of the rolling element, α The nominal contact angle of the bearing. d m The bearing pitch circle diameter, , These are the inner and outer raceway groove curvature radii, respectively. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively.

[0032] According to the ISO / TS 16281 standard, the basic rated dynamic load between the inner ring, outer ring, and rollers of a radial spherical roller bearing is: ; ; in, C r This represents the basic radial dynamic load rating of the bearing. i For the number of rollers, Z The number of scroll bodies per column, α The nominal contact angle of the bearing. r i , re These are the inner and outer raceway groove curvature radii, respectively. D w The diameter of the rolling element, , d m This refers to the bearing pitch circle diameter.

[0033] The basic rated dynamic load of the bearing axial direction is calculated using the following formula: ; ; in, , D w The diameter of the rolling element, d m The diameter of the roller pitch circle. α The nominal contact angle of the bearing. Z The number of scroll bodies per column, l , or This is the bearing correction factor. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. F(D w ) This is a correction function whose value is determined by the roller diameter: ; The rated dynamic load for a thrust ball bearing with multiple rows of rollers is: ; in, i For the number of columns of the rolling body, C aj For the first j Axial dynamic load rating of rolling element ball bearings Z j The number of scroll elements in column j.

[0034] The basic rated dynamic load between the inner ring, outer ring, and rollers of the axial thrust ball roller bearing is: ; ; in, C aD This represents the basic axial dynamic load rating of the bearing. Z The number of rollers per column, α The nominal contact angle of the bearing. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively.r i , r e These are the inner and outer raceway groove curvature radii, respectively. D w The diameter of the rolling element.

[0035] When the outer ring is fixed and the inner ring rotates relative to the load, the equivalent dynamic load between the inner ring, the outer ring, and the rollers is: ; in, Z The number of rollers per column, For the first j The load of each roller, F It can be a radial load or an axial load. The raceway life correction factor for axial thrust ball roller bearings is defined according to ISO 281 and ISO / TS 16281 standards. a isoa The calculation formula is: ; Radial spherical roller bearing raceway life correction factor a isor The calculation formula is: ; in, k This refers to the viscosity ratio of the lubricant. e c As a lubricant contaminant, C u For fatigue load life, P This is the equivalent dynamic load of the raceway.

[0036] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A three-row roller slewing bearing for a direct-drive wind turbine generator set, characterized in that: It includes an inner ring, an outer ring, and three rows of rolling elements disposed between the inner and outer rings. The three rows of rolling elements consist of a row of radial spherical rollers and two rows of axial thrust spherical rollers. Each row contains one or more rows of spherical roller structures. The row of radial spherical rollers is used to bear radial loads, and the two rows of axial thrust spherical rollers are used to bear axial loads and overturning moments simultaneously.

2. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 1, characterized in that: This includes static strength design, bearing working contact angle design, and fatigue life design. Static strength design: Based on Hertzian point contact theory, a ball-roller-raceway contact stress calculation model is established to solve for the maximum Hertzian contact stress at the contact point, and the static strength safety factor is checked in conjunction with the contact fatigue limit strength of the bearing material. Bearing working contact angle design: Based on the deformation geometry of the bearing under combined loads, the contact angle at any position of the bearing is determined. Fatigue life design: Based on the bearing's rated dynamic load and equivalent dynamic load, the reference rated life of the bearing is calculated in conjunction with the life correction factor.

3. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 2, characterized in that: The static strength design includes: calculating the first maximum Hertz contact stress between the radial spherical roller and the raceway, and the second maximum Hertz contact stress between the axial thrust spherical roller and the raceway; calculating the static strength safety factor of the radial raceway based on the first maximum Hertz contact stress and the Vickers hardness of the raceway surface; and calculating the static strength safety factor of the axial raceway based on the second maximum Hertz contact stress and the Vickers hardness of the raceway surface.

4. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 3, characterized in that: The formulas for calculating the first maximum Hertz contact stress between the radial spherical roller and the raceway and the second maximum Hertz contact stress between the axial thrust spherical roller and the raceway are both: ； ； ； in, Equivalent elastic modulus E 1 and E 2 represents the elastic modulus of the roller and raceway, respectively. ν 1 and ν 2 represents the Poisson's ratio of the roller and the raceway, respectively; , Let be the algebraic sum of the principal curvatures of the contact surfaces between the roller and the raceway; Q The normal force between the roller and the raceway; This is a complete elliptic integral of the second kind. e Let be the eccentricity of the ellipse.

5. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 4, characterized in that: The first maximum Hertz contact stress was calculated separately. q rmax Second maximum Hertz contact stress q amax Substitute into the following formulas respectively q max In the calculation, the static strength safety factors for the radial raceway and the axial raceway are respectively calculated as follows: S r and S a : ； in, HV The Vickers hardness of the raceway surface, [ q [This represents the allowable Hertz contact stress for static strength.] q max This is the maximum pressure on the contact surface between the roller and the raceway.

6. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 5, characterized in that: The geometric relationship after contact deformation is as follows: ； in, For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the inner and outer groove curvature coefficients, D. w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

7. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 6, characterized in that: exist The contact angle is largest at [location name], at [location name]. The contact angle is smallest at this location: ； ； in, For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the inner and outer groove curvature coefficients, D. w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

8. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 7, characterized in that: Bearing reference rated life L 10r Represented as: ； in, a isor This is the life correction factor for radial spherical rollers. Q rci The rated dynamic load for the radial spherical roller inner ring, Q rei The equivalent dynamic load on the radial spherical roller inner ring is... Q rce The rated dynamic load for the radial spherical roller outer ring, Q ree Equivalent dynamic load on the radial spherical roller outer ring; a isoa This is the life correction factor for axial thrust ball rollers. Q aci This represents the basic rated dynamic load between the inner ring and the rollers of an axial thrust ball roller bearing. Q ace This represents the basic rated dynamic load between the outer ring and rollers of an axial thrust ball roller bearing. Q aei For the first m Equivalent dynamic load between the inner ring and rollers of an axial thrust ball roller bearing. Q aee For the first m Equivalent dynamic load between the outer ring and rollers of an axial thrust ball roller bearing.

9. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 8, characterized in that: The point contact load between the raceway and the ball roller is: ； in, K n The coefficients related to Hertzian contact. For axial deformation at the contact point, For radial deformation at the contact point, The position angle of the ball, coefficient , f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. D w The diameter of the rolling element, α 0 represents the initial contact angle of the bearing.

10. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 9, characterized in that: The simplified basic radial dynamic load rating of the bearing is calculated using the following formula: ； in, i For the number of columns of the rolling body, α The nominal contact angle of the bearing. Z For the number of single-column scroll bodies, D w The diameter of the rolling element, f c The following formula is used for calculation: ； in, λ The reduction factor related to the quality of bearing manufacturing and installation. ,and D w The diameter of the rolling element, α The nominal contact angle of the bearing. d m The bearing pitch circle diameter, , These are the inner and outer raceway groove curvature radii, respectively. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively.

11. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 10, characterized in that: According to the ISO / TS 16281 standard, the basic rated dynamic load between the inner ring, outer ring, and rollers of a radial spherical roller bearing is: ； ； in, C r This represents the basic radial dynamic load rating of the bearing. i For the number of rollers, Z The number of scroll bodies per column, α The nominal contact angle of the bearing. r i , r e These are the inner and outer raceway groove curvature radii, respectively. D w The diameter of the rolling element, , d m This refers to the bearing pitch circle diameter.

12. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 11, characterized in that: The basic axial dynamic load rating of the bearing is calculated using the following formula: ； ； in, , D w The diameter of the rolling element, d m The diameter of the roller pitch circle. α The nominal contact angle of the bearing. Z The number of scroll bodies per column, λ , η This is the bearing correction factor. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. F(D w ) This is a correction function whose value is determined by the roller diameter: ； The rated dynamic load for a thrust ball bearing with multiple rows of rollers is: ； in, i For the number of columns of the rolling body, C aj For the first j Axial dynamic load rating of rolling element ball bearings Z j The number of scroll elements in column j.

13. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 12, characterized in that: The basic rated dynamic load between the inner ring, outer ring, and rollers of the axial thrust ball roller bearing is: ； ； in, C aD This represents the basic axial dynamic load rating of the bearing. Z The number of rollers per column, α The nominal contact angle of the bearing. f i , f e These are the curvature coefficients of the inner and outer grooves, respectively. r i , r e These are the inner and outer raceway groove curvature radii, respectively. D w The diameter of the rolling element.

14. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 13, characterized in that: When the outer ring is fixed and the inner ring rotates relative to the load, the equivalent dynamic load between the inner ring, the outer ring, and the rollers is: ； in, Z The number of rollers per column, For the first j The load of each roller, F It can be a radial load or an axial load.

15. The design method of the three-row roller slewing bearing for a direct-drive wind turbine generator set according to claim 14, characterized in that: The raceway life correction factor for axial thrust ball roller bearings is defined according to ISO 281 and ISO / TS 16281 standards. a isoa The calculation formula is: ； Radial spherical roller bearing raceway life correction factor a isor The calculation formula is: ； in, κ This refers to the viscosity ratio of the lubricant. e c As a lubricant contaminant, C u For fatigue load life, P This is the equivalent dynamic load of the raceway.

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