Wind turbine main shaft structure

Abstract

This invention relates to the field of wind turbine technology, specifically to a wind turbine main shaft structure. The wind turbine main shaft structure includes a hub, a transmission frame, a main shaft, a nacelle base, a main bearing, and a rear bearing. The hub and transmission frame are respectively connected to both ends of the main shaft. The nacelle base has a main bearing seat and a rear bearing seat at both ends along the axial direction of the main shaft, with the main bearing connected to the main bearing seat and the rear bearing connected to the rear bearing seat. The main shaft is rotatably connected to the nacelle base via the main bearing, and the transmission frame is rotatably connected to the nacelle base via the rear bearing. The transmission frame is used for transmission connection with the generator. This wind turbine main shaft structure reduces the weight and load of the unit components, and the segmented design of the main shaft reduces the difficulty of main shaft machining. The structural installation design of the front and rear bearings improves the rigidity of the entire transmission chain and eliminates the requirement for vibration-damping torque arms in independent shaft transmission chains.

Description

Technical Field

[0001] This invention relates to the field of wind turbine technology, and more specifically, to a main shaft structure for a wind turbine generator set. Background Technology

[0002] In the development of long-bladed, large-capacity wind turbine generators, adopting speed-increasing wind turbine generators is an important technical route to improve product economy and reduce manufacturing difficulty. For speed-increasing wind turbine generators, the core requirement is to design a main drivetrain structure that meets high reliability requirements. According to existing technology, for independent shaft drivetrains, the manufacturing difficulty is relatively low because the bearing housing is a separate structure. However, for integrated drivetrains, while existing TRB tapered roller bearings have high rigidity and load-bearing capacity, the interface size of these bearings is increasing with the application of large-megawatt offshore and onshore units. This increases the risk of bearing misalignment, as the increased size means larger bearing tolerances and increased unevenness in the bearing annular assembly interference area. Furthermore, the increased span and interface size of the front and rear bearings, along with the corresponding increase in the size of the main shaft and bearing housing, places significant demands on processing equipment. Therefore, in the development of large-megawatt wind turbine generator technology, the following problems exist: how to reduce the difficulty of manufacturing and processing, and how to provide high rigidity and load-bearing characteristics for the main drivetrain of the unit. Summary of the Invention

[0003] The present invention aims to provide a wind turbine generator main shaft structure that adopts a speed-increasing wind turbine generator, which can reduce the weight and load of the generator components. Moreover, the main shaft adopts a segmented design, which can reduce the difficulty of main shaft processing. The structural installation design of its front and rear bearings can improve the rigidity of the entire transmission chain and eliminate the requirement that the torque arm of the independent shaft transmission chain must be vibration-damping.

[0004] The embodiments of the present invention can be implemented as follows: This invention provides a wind turbine generator main shaft structure, which includes a hub, a transmission frame, a main shaft, a nacelle base, a main bearing, and a rear bearing. The hub and transmission frame are respectively connected to both ends of the main shaft; the engine compartment base is provided with a main bearing seat and a rear bearing seat at both ends along the axis of the main shaft, the main bearing is connected to the main bearing seat, and the rear bearing is connected to the rear bearing seat. The main shaft is rotatably connected to the engine room base via the main bearing, and the transmission frame is rotatably connected to the engine room base via the rear bearing; The transmission frame is used for transmission connection with the generator.

[0005] In an optional embodiment, the main bearing includes an outer ring, an inner ring, radial rollers, and two axial rollers; The outer ring is interference-fitted with the main bearing housing, the inner ring is connected to the main shaft, and the outer ring and the inner ring together form a radial raceway and two axial raceways. The radial raceway is located between the two axial raceways, and the extension direction of the radial raceway is perpendicular to the extension direction of the axial raceways. The radial rollers are mounted on the radial raceways, and the two axial rollers are mounted on the two axial raceways respectively.

[0006] In an optional embodiment, the outer ring includes a first ring and a second ring; The first raceway and the inner raceway form a radial raceway and one of the axial raceways, and the second raceway and the inner raceway form another axial raceway. The radial raceway portion of the first raceway is recessed towards the main bearing, while the radial raceway portion of the inner raceway protrudes towards the main bearing, and the axial raceway is located on both sides of the protruding portion of the inner raceway towards the main bearing.

[0007] In an optional embodiment, the wind turbine generator main shaft structure further includes a main bearing outer ring connector and a main bearing inner ring connector; Both the first and second races are connected to the main bearing housing via the main bearing outer race connector; The inner ring is connected to the main bearing via the main bearing inner ring connector, and the wheel hub is connected to the main bearing via the main bearing inner ring connector.

[0008] In an optional embodiment, one end of the main bearing outer ring connector is sequentially inserted into the main bearing housing, the second ring, and the first ring, while the other end is fixedly connected to a nut and located inside the engine compartment base. One end of the main bearing inner ring connector is inserted into the main shaft, inner ring and hub in sequence, and the other end is fixedly connected to the nut and located in the engine compartment base.

[0009] In an optional embodiment, the rear bearing includes a cylindrical roller bearing and a rear bearing end cap; The rear bearing end cover is connected to the rear bearing housing, and the rear bearing housing is equipped with an axial shoulder. The outer ring of the cylindrical roller bearing is connected to the rear bearing housing, and both ends of the outer ring abut against the rear bearing end cover and the axial shoulder, respectively; the inner ring of the cylindrical roller bearing is connected to the transmission frame.

[0010] In an optional implementation, the wind turbine main shaft structure also includes a transmission connection frame and a planetary gear system for the generator.

[0011] In an optional implementation, the planetary gear train includes a planetary ring gear, a sun gear, and multiple planetary gears; The planetary ring gear is connected to the rear bearing housing; multiple planetary gears are rotatably connected to the transmission frame, and the planetary ring gear is located on the outer periphery of the multiple planetary gears, and the multiple planetary gears mesh with the planetary ring gear; The sun gear is located inside multiple planet gears, and multiple planet gears mesh with the sun gear; The sun gear is used for transmission connection with the generator.

[0012] In an optional embodiment, the wind turbine generator main shaft structure further includes a speed-increasing gearbox and a parallel meshing gear. The speed-increasing gearbox is connected to the sun gear drive, and the parallel meshing gear drive connects the generator and the speed-increasing gearbox. The housing of the speed-increasing gearbox is connected to the planetary gear ring.

[0013] In an optional embodiment, the wind turbine generator main shaft structure further includes a secondary gear train; the secondary gear train drives and connects the sun gear and the generator; the housing of the secondary gear train is connected to the outer casing of the generator, and the housing of the secondary gear train is connected to the planetary gear ring.

[0014] The beneficial effects of the wind turbine generator main shaft structure provided in this embodiment of the invention include: The main shaft structure of the wind turbine generator set includes a hub, drive frame, main shaft, nacelle base, main bearing, and rear bearing. The hub and drive frame are respectively connected to both ends of the main shaft. The nacelle base has main bearing seats and rear bearing seats at both ends along the axis of the main shaft. The main bearing is connected to the main bearing seat, and the rear bearing is connected to the rear bearing seat. The main shaft is rotatably connected to the nacelle base via the main bearing, and the drive frame is rotatably connected to the nacelle base via the rear bearing. The drive frame is used for transmission connection with the generator. This wind turbine generator set's main shaft structure adopts a speed-increasing type, which can reduce the weight and load of the unit components. Furthermore, the segmented design of the main shaft reduces the difficulty of main shaft machining. The structural installation design of its front and rear bearings improves the rigidity of the entire transmission chain and eliminates the requirement for vibration-damping torque arms in independent shaft transmission chains. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the main shaft structure of the wind turbine generator provided in this embodiment; Figure 2 for Figure 1 A partial schematic diagram of point A in the middle; Figure 3 for Figure 1 A partial schematic diagram at point B in the middle; Figure 4This is a schematic diagram of the wind turbine generator main shaft structure provided in this embodiment when applied to a doubly fed wind turbine generator set. Figure 5 This is a schematic diagram of the wind turbine generator main shaft structure provided in this embodiment when applied to a medium-speed permanent magnet wind turbine generator.

[0017] Icons: 100 - Wind turbine main shaft structure; 110 - Hub; 120 - Drive frame; 130 - Main shaft; 140 - Nacelle base; 150 - Main bearing; 160 - Rear bearing; 170 - Main bearing housing; 180 - Rear bearing housing; 151 - Outer ring; 152 - Inner ring; 153 - Radial roller; 154 - Axial roller; 155 - First ring; 156 - Second ring; 157 - Main bearing outer ring connector; 158 - Main bearing inner ring connector; 161 - Cylindrical roller bearing; 162 - Rear bearing end cover; 163 - Axial shoulder; 190 - Planetary gear train; 191 - Planetary ring gear; 192 - Sun gear; 193 - Planetary gear; 210 - Speed-increasing gearbox; 220 - Parallel meshing gear; 230 - Generator; 240 - Secondary gear train. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0021] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0023] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0024] The inventors discovered through research that the main drive chain structure of large-megawatt wind turbine generator sets can be divided into permanent magnet direct-drive units and gearbox speed-increasing units. Among them, permanent magnet units are mainly divided into main drive chains supported by single main bearings and main drive chains supported by double main bearings, based on the bearing type. The bearing types of single main bearing support are mainly three-row column bearings and double-row tapered roller bearings, which are bolted to the corresponding moving and fixed shafts. The structure is relatively simple, and this type of bearing has high rigidity and high load-bearing characteristics. The main drive chain supported by double main bearings is basically composed of two single-row tapered roller bearings, which are connected to the corresponding moving and fixed shafts through interference fit. For gearbox speed-increasing units, depending on whether the main shaft system is integrated with the main gearbox, they can be divided into independent shaft drive chains and integrated drive chains. In the independent shaft drive chain, the stationary part (bearing housing) of the main shaft system is connected to the base separately, the main gearbox housing is connected to the base through a torque arm, and the rotating part of the main shaft is connected to the first-stage planetary carrier of the gearbox. This structure mainly uses a single SRB main bearing, and the matching gearbox torque arm must be connected to the base through a shock-absorbing pad. The integrated drive train means that the stationary ring (bearing housing) of the main shaft system is directly connected to the first-stage gear ring of the main gearbox, eliminating the torque arm and corresponding damping device, resulting in a more compact structure. The entire weight of the gearbox is suspended on the connecting flange at the end of the bearing housing (for medium-speed permanent magnet wind turbine generator sets, this also includes the generator, which is also suspended at the end of the bearing housing through the main gearbox housing). The bearing housing is then directly connected to the nacelle base. This type of shaft system structure is relatively compact, and its main shaft system main bearings must use TRB tapered roller bearings, and the front and rear main bearing assembly housings must use integrated bearing housings. For independent shaft drive chains, as the units develop towards larger megawatt capacities and longer blades, the axial load and bending moment of the units are also increasing exponentially. The single SRB bearing itself has a self-aligning function and can only bear radial loads and part of the axial loads. At the same time, it has a large positive clearance, which has a large impact on the axial operation of the SRB bearing, thus affecting the operation of the main gearbox. For integrated drive trains, with the application of large-megawatt units at sea and on land, the size of their TRB bearing interfaces is also increasing. This increases the risk of bearing misalignment, as the increased size means larger bearing size tolerances and increased unevenness of the bearing ring assembly interference area. On the other hand, the increase in the front and rear bearing span and interface size leads to an increase in the corresponding spindle and bearing housing size, which places great demands on the processing equipment. Using direct-drive generator sets will directly result in larger generator diameters and greater weight, leading to an increase in the diameter of the supporting main bearings, which severely restricts the processing and manufacturing capabilities of the supply chain. In the development of long-bladed, large-capacity wind turbine generators, adopting speed-increasing wind turbine generators is an important technical route to improve product economy and reduce the difficulty of product manufacturing. For speed-increasing wind turbine generators, the core requirement is how to design a main drive train structure that meets high reliability. According to existing technology, for independent shaft drive trains, the manufacturing difficulty is relatively low because the bearing housing is a separate structure. However, for integrated drive trains, although the existing TRB tapered roller bearings have high rigidity and load-bearing capacity, with the application of large-megawatt units at sea and onshore, the interface size of the TRB bearings is also increasing. This increases the risk of bearing misalignment, because the increase in size means a larger bearing dimensional tolerance and an increased unevenness of the bearing annular assembly interference area. On the other hand, the increase in the front and rear bearing span and interface size also increases the corresponding main shaft and bearing housing size, which places great demands on the processing equipment.

[0025] For the reasons mentioned above, please refer to Figures 1-3 This embodiment provides a wind turbine generator main shaft structure 100, which includes a hub 110, a transmission frame 120, a main shaft 130, a nacelle base 140, a main bearing 150, and a rear bearing 160. The hub 110 and the transmission frame 120 are respectively connected to the two ends of the main shaft 130; the engine compartment base 140 is provided with a main bearing seat 170 and a rear bearing seat 180 at both ends along the axial direction of the main shaft 130, the main bearing 150 is connected to the main bearing seat 170, and the rear bearing 160 is connected to the rear bearing seat 180. The main shaft 130 is rotatably connected to the nacelle base 140 via the main bearing 150, and the transmission frame 120 is rotatably connected to the nacelle base 140 via the rear bearing 160. The transmission frame 120 is used for transmission connection with the generator 230.

[0026] Please refer to Figures 1-3 The working principle of the main shaft structure 100 of the wind turbine generator is as follows: Compared to the main shaft 130 of the wind turbine generator 230 in the prior art, this embodiment forms a segmented structural design by configuring the hub 110, transmission frame 120 and main shaft 130. Moreover, when configuring the bearing connecting parts, a main bearing 150 and a rear bearing 160 are used. The main bearing 150 rotatably connects the main shaft 130 to the nacelle base 140, and the rear bearing 160 rotatably connects the transmission frame 120 to the nacelle base 140. The nacelle base 140 is equipped with independent main bearing seats 170 and rear bearing seats 180. Thus, based on the structural design of the main bearing 150, rear bearing 160, main bearing seats 170 and rear bearing seats 180, the installation requirements of the segmented structure can be met, while improving the overall rigidity and load-bearing capacity. In summary, the main shaft structure 100 of this wind turbine generator set adopts a speed-increasing wind turbine generator set 230, which can reduce the weight and load of the unit components. Moreover, the main shaft 130 adopts a segmented design, which can reduce the machining difficulty of the main shaft 130. The structural installation design of its front and rear bearings 160 can improve the rigidity of the entire transmission chain and eliminate the requirement that the torque arm of the independent shaft transmission chain must be vibration-damping.

[0027] Further, please refer to Figures 1-3 In this embodiment, when configuring the main bearing 150 and the rear bearing 160, the main bearing 150 is configured as a three-row column bearing, while the rear bearing 160 is configured as a cylindrical roller bearing 161. This method, by using a single-bearing three-row column main bearing 150, can significantly improve the load-bearing characteristics of the main shaft 130 system. At the same time, based on the three-row column single main bearing 150, an independent main bearing housing 170 is designed, which can significantly reduce the size requirements of the bearing housing for the existing integrated transmission chain. Furthermore, based on the three-row column main bearing 150, the shaft system stiffness characteristics are significantly improved. Moreover, the transmission frame 120 used to drive the generator 230 is connected to the nacelle base 140 through the rear bearing 160. In this way, it can improve the stiffness characteristics of the main transmission chain, sharing the load with the three-row column main bearing 150.

[0028] Therefore, the main shaft structure 100 of the wind turbine generator set adopts the speed-increasing wind turbine generator set 230, which can reduce the weight and load of the unit components. The bearing type of its main bearing 150 is a three-row column bearing, which is bolted to the corresponding moving and fixed shafts. The scheme adopts a single bearing three-row column main bearing 150, which can significantly improve the load-bearing characteristics of the main shaft 130 series. Meanwhile, based on the three-row column single main bearing 150, an independent bearing housing is designed, which significantly reduces the size requirements of the bearing housing in the existing integrated transmission chain and greatly improves the stiffness characteristics of the shaft system. The planetary gear train 190 connected to the main shaft 130 is directly rigidly connected to the engine compartment base 140. At the same time, in order to improve the stiffness characteristics of the main gearbox input shaft, the transmission frame 120 is connected to the rear bearing housing 180 through the cylindrical roller bearing 161, and together with the three-row column main bearing 150, it bears the stiffness characteristics of the main transmission chain. The internal main shaft 130 adopts a segmented design, which also reduces the machining difficulty of the main shaft 130. The rear bearing 160 adopts a traditional bearing structure with inner and outer rings. Its rear bearing housing 180 is connected to the planetary gear ring 191, and the inner ring shaft is integrated with the first-stage planetary gear train 190 of the main gearbox. The bearing housing and the engine compartment base 140 are rigidly connected, eliminating the requirement that the torque arm of the independent shaft transmission chain must be vibration damping, and improving the stiffness of the entire transmission chain.

[0029] For details, please refer to Figures 1-3 In this embodiment, the main bearing 150 includes an outer ring 151, an inner ring 152, radial rollers 153, and two axial rollers 154. The outer ring 151 is interference-fitted with the main bearing housing 170, and the inner ring 152 is connected to the main shaft 130. The outer ring 151 and the inner ring 152 together form a radial raceway and two axial raceways. The radial raceway is located between the two axial raceways, and the extension direction of the radial raceway is perpendicular to the extension direction of the axial raceways. The radial rollers 153 are mounted on the radial raceways, and the two axial rollers 154 are respectively mounted on the two axial raceways. Among them, the two axial rollers 154 mainly bear the axial force and bending moment transmitted by the hub 110, while the radial rollers 153 mainly bear the radial force transmitted by the hub 110. When configuring the outer ring 151, it is adopted that the outer ring 151 includes a first ring 155 and a second ring 156; the first ring 155 and the inner ring 152 form a radial raceway and one of the axial raceways, and the second ring 156 and the inner ring 152 form another axial raceway; in order to improve the load-bearing capacity of the radial roller 153, the portion of the radial raceway formed by the first ring 155 is recessed towards the main bearing 150, and the portion of the radial raceway formed by the inner ring 152 is recessed towards the main bearing 150. The axial raceway is located on both sides of the protruding portion of the inner ring 152 towards the main bearing 150. This arrangement allows the radial raceway design to have the outer ring 151 being concave and the inner ring 152 being convex. Compared to the existing industry practice of having the outer ring 151 being convex and the inner ring 152 being concave, this structural arrangement can increase the pitch circle diameter of the radial roller 153 and reduce the load on the radial roller 153. Furthermore, since the outer ring 151 includes a first ring 155 and a second ring 156, i.e., the outer ring 151 adopts a segmented design, it can meet the design requirements of the concave outer ring and increase the pitch circle diameter of the radial roller 153. After the outer ring 151 is segmented, the first ring 155 and the second ring 156 are connected by the main bearing outer ring connector 157. Under normal operation, after the end faces of the first ring 155 and the second ring 156 are pre-tightened by the main bearing outer ring connector 157, the mating surface is tensioned. However, after the bearing is subjected to bending moment load, due to structural deformation and bolt loosening, the mating surface may open, resulting in grease leakage. Therefore, the outer ring surfaces of the first ring 155 and the second ring 156 are fitted with the ring surface of the main bearing housing 170 by interference fit, which further improves the circumferential stiffness of the main bearing 150 and reduces the risk of the segmented bearing mating surface opening.

[0030] When installing the outer ring 151 and inner ring 152, please refer to... Figures 1-3 The wind turbine generator main shaft structure 100 includes a main bearing outer ring connector 157 and a main bearing inner ring connector 158; the first ring 155 and the second ring 156 are both connected to the main bearing housing 170 through the main bearing outer ring connector 157; the inner ring 152 is connected to the main bearing 150 through the main bearing inner ring connector 158, and the hub 110 is connected to the main bearing 150 through the main bearing inner ring connector 158; through this arrangement, the hub 110 can... The outer ring of the main bearing is connected to the front end face of the inner ring 152 via the outer ring connector 157. The inner ring 152 integrates the running raceways of the radial rollers 153 and two axial rollers 154, which transmit the bending moment load of the hub 110 to the first ring 155 and the second ring 156 through the inner ring 152, and to the engine compartment base 140 through the main bearing housing 170. The first ring 155 and the second ring 156 are connected and fixed to the main bearing housing 170 by the outer ring connector 157.

[0031] Furthermore, one end of the main bearing outer ring connector 157 is sequentially inserted into the main bearing housing 170, the second ring 156, and the first ring 155, while the other end is fixedly connected to a nut and located inside the engine compartment base 140; one end of the main bearing inner ring connector 158 is sequentially inserted into the main shaft 130, the inner ring 152, and the hub 110, while the other end is fixedly connected to a nut and located inside the engine compartment base 140. This allows one end of the main bearing outer ring connector 157 to pass through the first race 155 and the second race 156, while the other end is fixed with a nut, facilitating later operation and maintenance. Thus, the non-torsional load transmitted by the hub 110 can be transferred to the engine compartment base 140 through the three-row main bearing 150. One end of the inner race 152 is connected to the hub 110, and the other end is connected to the main shaft 130. The three components are connected and fixed through the main bearing outer ring connector 157. At the same time, one end of the main bearing outer ring connector 157 passes through the threaded hole of the hub 110, and the other end is fixed with a nut, ensuring that the bolts of the inner and outer races can be maintained simultaneously in the engine compartment.

[0032] Further, please refer to Figures 1-3 In this embodiment, the wind turbine generator main shaft structure 100 also includes a planetary gear train 190 that connects the transmission frame 120 and the generator 230. It should be noted that the wind turbine generator main shaft structure 100 uses a main gearbox to connect the main shaft 130 and the generator 230. In this embodiment, the planetary gear train 190 is installed in the main gearbox; that is, the planetary gear train 190 is part of the main gearbox. Furthermore, the transmission frame 120 is configured as a planetary carrier to facilitate connection with the planetary gear train 190. The main shaft 130 transmits the torque from the hub 110 to the planetary gear train 190. To ensure the reliability of the connection between the main shaft 130 and the transmission frame 120, the end of the main shaft 130 is connected to the transmission frame 120 by a pin to transmit torque. Specifically, the planetary gear train 190 includes a planetary ring gear 191, a sun gear 192, and multiple planetary gears 193; the planetary ring gear 191 is connected to the rear bearing housing 180; the multiple planetary gears 193 are rotatably connected to the transmission frame 120, and the planetary ring gear 191 is located on the outer periphery of the multiple planetary gears 193, and the multiple planetary gears 193 mesh with the planetary ring gear 191; the sun gear 192 is located on the inner side of the multiple planetary gears 193, and the multiple planetary gears 193 mesh with the sun gear 192; wherein, the sun gear 192 is used for transmission connection with the generator 230.

[0033] With this configuration, the inner ring 152, main shaft 130 and transmission frame 120 can be directly driven to rotate by the rotation of hub 110. Transmission frame 120 is a planetary carrier with multiple planetary gears 193 installed. Planetary gear ring 191, sun gear 192 and multiple planetary gears 193 form planetary gear train 190. During the rotation of transmission frame 120, the sun gear 192 is accelerated through planetary gear train 190 and transmitted to the next stage gear train or generator 230.

[0034] Based on the above, please refer to Figures 1-3 The high rigidity and high load-bearing capacity of the three-row main bearing 150 ensure that the rotation transmitted from the main shaft 130 to the transmission frame 120 is a pure torque load. To prevent axial movement of the main front bearing from being transmitted to the subsequent speed-increasing planetary gear train 190, the rear bearing housing 180 used to fix the planetary gear train 190 is directly rigidly connected to the engine room base 140. At the same time, to avoid the deformation of the end of the main shaft 130 affecting the meshing of the planetary gears 193 and the sun gear 192 of the planetary gear train 190, when the transmission frame 120 is used as a planetary carrier, the transmission frame 120 is connected to the engine room base 140 through a cylindrical roller bearing 161. This arrangement further improves the bearing support rigidity of the entire main drive chain. The inner ring of the cylindrical roller bearing 161 is fixed to the transmission frame 120, while the outer ring is fixed to the rear bearing housing 180.

[0035] Therefore, when configuring the rear bearing 160, the rear bearing 160 includes a cylindrical roller bearing 161 and a rear bearing end cover 162; the rear bearing end cover 162 is connected to the rear bearing housing 180, and the rear bearing housing 180 is provided with an axial shoulder 163; the outer ring of the cylindrical roller bearing 161 is connected to the rear bearing housing 180, and both ends of the outer ring abut against the rear bearing end cover 162 and the axial shoulder 163 respectively; the inner ring of the cylindrical roller bearing 161 is connected to the transmission frame 120. Moreover, since the cylindrical roller bearing 161 is a positive clearance bearing, in order to avoid the influence of axial movement, its outer ring needs to be fixed. Therefore, the outer ring is fixed to the rear bearing housing 180, and the axial shoulder 163 of the rear bearing housing 180 should be set at the leeward end. The outer ring is pressed against the mating end face by the rear bearing end cover 162, and it is necessary to ensure that the mating end face has a certain amount of pressing.

[0036] Based on the above structure, please refer to Figure 4 and combined Figures 1-3When the wind turbine main shaft structure 100 is applied to a doubly-fed wind turbine 230, the wind turbine main shaft structure 100 also includes a speed-increasing gearbox 210 and a parallel meshing gear 220. The speed-increasing gearbox 210 is connected to the sun gear 192, and the parallel meshing gear 220 is connected to the generator 230 and the speed-increasing gearbox 210. The housing of the speed-increasing gearbox 210 is connected to the planetary ring gear 191. Thus, the planetary gear train 190 is speed-increasing and outputs through the sun gear 192, and then transmits the speed to the next stage gear train. Finally, the speed-increasing output is achieved through the parallel meshing gear 220, enabling the doubly-fed motor to reach the required speed. The housing of the speed-increasing part of the main gearbox, namely the housing of the speed-increasing gearbox 210, is fixed to the planetary ring gear 191, so that the weight of all main gearboxes except the generator 230 is ultimately transmitted to the nacelle base 140 by the rear bearing housing 180.

[0037] Please refer to Figure 5 and combined Figures 1-3 Unlike the aforementioned speed-increasing gearbox 210 and parallel meshing gear 220, when the wind turbine generator main shaft structure 100 is applied to a medium-speed permanent magnet wind turbine generator 230, the wind turbine generator main shaft structure 100 also includes a secondary gear train 240; the secondary gear train 240 drives and connects the sun gear 192 and the generator 230; the housing of the secondary gear train 240 is connected to the housing of the generator 230, and the housing of the secondary gear train 240 is connected to the planetary gear ring 191.

[0038] Thus, after being accelerated, the planetary gear train 190 outputs power through the sun gear 192 and transmits it to the next secondary gear train 240. After being accelerated, the next secondary gear train 240 is directly connected to the rotor part of the generator 230. The housing of the generator 230 is rigidly connected to the housing of the secondary gear train 240. The housing of the secondary gear train 240 is fixed to the planetary ring gear 191, so that the weight of the entire planetary gear train 190, the secondary gear train 240 and the generator 230 is finally transmitted to the nacelle base 140 through the rear bearing housing 180.

[0039] Based on the above structural configuration, it should also be noted that since this embodiment adopts a split main shaft 130 structure, the appropriate lubrication method can be selected according to the actual load characteristics. For the lubrication of the rollers and raceways of the main bearing 150, due to the low speed and high torque characteristics of the large-megawatt wind turbine 230, grease is more likely to form a raceway oil film with a large oil film bearing capacity. Therefore, the grease lubrication seal of the main bearing 150 adopts a contact seal, which consists of the main bearing 150 sealing cover plate and the main bearing 150 sealing ring. The main bearing 150 sealing ring consists of two lips. The outer lip prevents external dust from entering, and the inner lip prevents grease leakage. The same structure is also applied to the gap between the downwind outer ring 151 and the inner ring 152 of the main bearing 150. As for the lubrication of the rear bearing 160, i.e. the cylindrical roller bearing 161, this bearing mainly bears torque load and is integrated with the gearbox. It uses thin oil lubrication shared with the gearbox and adopts contact seal. It consists of a rear bearing end cover 162, a rear bearing 160 sealing plate, and a rear bearing 160 sealing ring. The rear bearing end cover 162 not only increases the axial clamping amount of the outer ring of the cylindrical bearing, but also improves the fixation of the rear bearing 160 sealing plate. Similarly, the rear bearing 160 sealing ring consists of two lips. The outer lip prevents external dust from entering, and the inner lip prevents oil leakage.

[0040] In summary, please refer to Figures 1-3 The wind turbine generator main shaft structure 100 has the following advantages: The wind turbine generator main shaft structure 100 adopts a speed-increasing wind turbine generator 230, which can reduce the weight and load of the generator components. Its main bearing 150 is a three-row column bearing, which is bolted to the corresponding moving and fixed shafts. The scheme adopts a single bearing three-row column main bearing 150, which can significantly improve the load-bearing characteristics of the main shaft 130 series. A split bearing housing was adopted, with independent housings designed for the main bearing 150 and the rear bearing 160, significantly reducing the size requirements for the bearing housings. Furthermore, since the main bearing 150 bears both impeller end bending moment and torque, under large bending moment loading, structural deformation, coupled with uneven interference contact caused by large dimensional tolerances, easily leads to inner ring slippage. Therefore, a three-row column single main bearing 150 structure was adopted, eliminating the conventional thermal fitting between the main bearing 150 inner ring and the shaft, and using bolt connections to completely solve the inner ring slippage problem of the main bearing 150. The problem of slippage with the rotating shaft is solved, and the requirement for an integrated bearing housing for the tapered roller main bearing 150 is avoided, reducing the machining difficulty of the main shaft 130. A cylindrical roller bearing 161 is added to the planetary gear train 190 of the main gearbox, with axial fixed constraints, to further improve the transmission rigidity of the main drive chain. Its bearing housing is connected to the first-stage planetary gear ring 191, and the inner ring rotating shaft is integrated with the first-stage planetary gear train 190 of the main gearbox. The bearing housing is rigidly connected to the engine compartment base 140, eliminating the requirement that the torque arm of the independent shaft drive chain must be vibration damping, and improving the rigidity of the entire drive chain. The three-row column bearing structure features a radial roller 153 raceway design where the outer ring 151 is concave with an outer radial raceway, while the inner ring 152 has a convex inner radial raceway. This design, compared to existing industry designs where the outer ring 151 is convex and the inner ring 152 is concave, increases the pitch circle diameter of the radial roller 153 during circumferential motion and reduces the load on the radial roller 153. Furthermore, the outer ring surfaces of the outer and lower outer rings 151 are interference-fitted with the ring surface of the main bearing housing 170, further improving the circumferential stiffness of the main bearing 150 and reducing the risk of the segmented bearing mating surfaces opening. The 130 series main shaft adopts a split design, and the appropriate lubrication method can be selected according to the actual load characteristics. For the lubrication of the front main bearing 150, due to the low speed and high torque characteristics of the 230 series of large-megawatt wind turbines, grease is more likely to form a raceway oil film with a large oil film bearing capacity. Therefore, the grease lubrication seal of the front bearing adopts a contact seal. For the rear bearing 160, this bearing mainly bears the torque load and is integrated with the gearbox. It adopts thin oil lubrication shared with the gearbox. The main drive chain has a certain tilt angle, so the tilt angle characteristic can be utilized to adopt a combination of labyrinth seal and packing contact seal.

[0041] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A main shaft structure for a wind turbine generator set, characterized in that: The wind turbine generator main shaft structure includes a hub, a transmission frame, a main shaft, a nacelle base, a main bearing, and a rear bearing; The hub and the transmission frame are respectively connected to both ends of the main shaft; the engine compartment base is provided with a main bearing seat and a rear bearing seat at both ends along the axial direction of the main shaft, the main bearing is connected to the main bearing seat, and the rear bearing is connected to the rear bearing seat. The main shaft is rotatably connected to the engine compartment base via the main bearing, and the transmission frame is rotatably connected to the engine compartment base via the rear bearing; The transmission frame is used for transmission connection with the generator.

2. The wind turbine generator main shaft structure according to claim 1, characterized in that: The main bearing includes an outer ring, an inner ring, radial rollers, and two axial rollers; The outer ring is interference-fitted with the main bearing housing, the inner ring is connected to the main shaft, and the outer ring and the inner ring together form a radial raceway and two axial raceways. The radial raceway is located between the two axial raceways, and the extension direction of the radial raceway is perpendicular to the extension direction of the axial raceways. The radial rollers are mounted on the radial raceways, and the two axial rollers are respectively mounted on the two axial raceways.

3. The wind turbine generator main shaft structure according to claim 2, characterized in that: The outer ring includes a first ring and a second ring; The first collar and the inner collar form the radial raceway and one of the axial raceways, and the second collar and the inner collar form the other axial raceway; The portion of the first raceway forming the radial raceway is recessed toward the main bearing, the portion of the inner raceway forming the radial raceway protrudes toward the main bearing, and the axial raceway is located on both sides of the protruding portion of the inner raceway toward the main bearing.

4. The wind turbine generator main shaft structure according to claim 3, characterized in that: The wind turbine generator main shaft structure also includes a main bearing outer ring connector and a main bearing inner ring connector. Both the first and second races are connected to the main bearing housing via the main bearing outer race connector; The inner ring is connected to the main bearing via the main bearing inner ring connector, and the wheel hub is connected to the main bearing via the main bearing inner ring connector.

5. The wind turbine generator main shaft structure according to claim 4, characterized in that: One end of the main bearing outer ring connector is sequentially inserted into the main bearing housing, the second ring and the first ring, and the other end is fixedly connected to a nut and located inside the engine compartment base; One end of the main bearing inner ring connector is inserted sequentially into the main shaft, the inner ring, and the hub, while the other end is fixedly connected to a nut and located inside the engine compartment base.

6. The wind turbine generator main shaft structure according to claim 1, characterized in that: The rear bearing includes a cylindrical roller bearing and a rear bearing end cap; The rear bearing end cap is connected to the rear bearing housing, and the rear bearing housing is provided with an axial shoulder; The outer ring of the cylindrical roller bearing is connected to the rear bearing housing, and both ends of the outer ring abut against the rear bearing end cap and the axial shoulder, respectively; the inner ring of the cylindrical roller bearing is connected to the transmission frame.

7. The wind turbine generator main shaft structure according to any one of claims 1-6, characterized in that: The wind turbine generator main shaft structure also includes a planetary gear system that drives the transmission frame and the generator.

8. The wind turbine generator main shaft structure according to claim 7, characterized in that: The planetary gear train includes a planetary ring gear, a sun gear, and multiple planetary gears; The planetary ring gear is connected to the rear bearing housing; the plurality of planetary gears are rotatably connected to the transmission frame, and the planetary ring gear is located on the outer periphery of the plurality of planetary gears, and the plurality of planetary gears mesh with the planetary ring gear; The sun gear is located inside the plurality of planet gears, and the plurality of planet gears are all meshed with the sun gear; The sun gear is used for transmission connection with the generator.

9. The wind turbine generator main shaft structure according to claim 8, characterized in that: The wind turbine generator main shaft structure also includes a speed-increasing gearbox and a parallel meshing gear. The speed-increasing gearbox is connected to the sun gear, and the parallel meshing gear is connected to the generator and the speed-increasing gearbox. The housing of the speed-increasing gearbox is connected to the planetary gear ring.

10. The wind turbine generator main shaft structure according to claim 8, characterized in that: The wind turbine generator main shaft structure also includes a secondary gear train; the secondary gear train drives the sun gear and the generator; the housing of the secondary gear train is connected to the outer casing of the generator, and the housing of the secondary gear train is connected to the planetary gear ring.

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