Main shaft system of wind turbine

Abstract

A main shaft system of a wind turbine relates to the technical field of wind power generation, and comprises a stationary shaft (1), a rotating shaft (2) and two bearings (3), wherein the rotating shaft (2) is sleeved on the outer side of a shaft main body portion (9) of the stationary shaft (1); a disc I (7) and a disc II (8) are sleeved outside the rotating shaft (2); a reinforcing rib I (11) is provided between the disc I (7) and the disc II (8); a recessed structure (12) is provided at the transition between the shaft main body portion (9) and a disc flange portion (10) of the stationary shaft (1); a transition ring (13) is provided in the recessed structure (12), axially extends to the bearing (3) outside the recessed structure (12), and is in interference fit with the bearing (3); and the outer cylindrical surface of the transition ring (13) is in interference fit with the rotating shaft (2), and the inner cylindrical surface of the transition ring (13) is in clearance fit with the stationary shaft (1). The rotating shaft (2) is sleeved on the outer side of the shaft main body portion (9) of the stationary shaft (1), such that the bearing capacity is stronger; the rotating shaft (2) uses a structure where dual discs share a reinforcing rib, such that a shaft system structure has relatively strong overall rigidity, and features a simple structure, light weight and good economic efficiency; and the transition ring (13) is provided at the recessed structure (12), thereby greatly reducing the stress concentration factor of the stationary shaft (1) and meeting the usage requirements of a large MW-class unit on the basis of meeting the usage requirements of a structure.

Description

A wind turbine main shaft system Technical Field

[0001] This invention relates to the field of wind power generation technology, and more specifically to a wind turbine main shaft system. Background Technology

[0002] Wind turbine generators mainly consist of blades, hubs, generators, main frames, towers, and other components. They capture wind energy through blades, which are mounted on the hub at their roots. The rotation of the blades converts wind energy into kinetic energy, which is then transferred to the generator through the hub. Finally, the generator converts the kinetic energy into electrical energy.

[0003] A wind turbine generator mainly consists of a stator, rotor, shaft system, and auxiliary components. The stator and rotor convert mechanical energy into electrical energy. The shaft system is the primary load transmission path. During energy conversion, the shaft system not only bears the torque generated by the generator's rotational motion but also various complex alternating loads, such as radial loads, axial loads, and bending moments. These loads are affected by various factors during the operation of the wind turbine generator and are prone to various failures. Therefore, the safety performance of the shaft system plays a decisive role in the normal operation of the wind turbine generator.

[0004] Furthermore, as the power output of wind turbine generators gradually increases, the load on the shaft system also increases dramatically, leading to a corresponding increase in the structural dimensions of the shaft system. Simultaneously, intensified market competition demands increasingly lower unit costs for wind turbine generators while simultaneously raising reliability requirements. These factors all place higher demands on the design and manufacturing of the shaft system.

[0005] In summary, the function of the main shaft system of a wind turbine is not only to transmit torque, but also to withstand complex alternating loads. Therefore, the shaft system structure of a wind turbine faces the dual challenges of performance and manufacturing cost.

[0006] The utility model patent with publication number CN210343620U discloses a direct-drive wind turbine shaft system structure, including a fixed shaft mounted on the main frame and a rotating shaft mounted on the hub. The outer side of the fixed shaft is provided with an upper wind bearing and a lower wind bearing to support the rotation of the rotating shaft. The cross-section of the side wall of the rotating shaft is a "V" shaped structure. The upper wind bearing and the lower wind bearing are located at the two ends of the "V" shaped structure, respectively. The third end of the "V" shaped structure is mounted on the hub, and extends outward along the third end to form a disc structure located on the outer ring of the rotating shaft. The cross-section of the side wall of the fixed shaft is an L-shaped structure. The upper wind bearing is located at one end of the fixed shaft, and the other end of the fixed shaft is mounted on the main frame.

[0007] However, the aforementioned patents have the following problems:

[0008] 1. The above patent uses two tapered roller bearings of equal size to provide support for the unit. The bearings are installed using a heat-shrink method. The design of equal size brings higher requirements to the installation and increases the assembly difficulty. The bearing span is greater than or equal to twice the distance between the mating surface of the shaft and the hub and the mating surface of the fixed shaft and the main frame. The entire shaft system is very long, the overall size is large, and the weight is heavy.

[0009] 2. The above-mentioned patent uses a design of two small bearings of equal size. The bearing and shaft system have weak load-bearing capacity. As the wind load increases, the bearing and shaft structure cannot meet the usage requirements and is not suitable for large MW-level wind turbines.

[0010] 3. The shaft system design of the above patent has low integration, and only realizes the basic functions of the shaft system, providing support for the unit and bearing wind loads. Summary of the Invention

[0011] This invention aims to provide a wind turbine main shaft system. This system utilizes two large single-row tapered roller bearings of unequal size for support, employing an outer ring rotating structure. The bearings have high load-bearing capacity, meeting the requirements of large MW-level units. Furthermore, the unequal size of the two bearings facilitates installation and reduces assembly difficulty. The bearing span is small, approximately equal to the distance from the mating surface of the shaft and hub to the mating surface of the fixed shaft and main frame, resulting in a small overall size, compact structure, and light weight.

[0012] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0013] A wind turbine main shaft system includes a fixed shaft mounted on a main frame, a rotating shaft mounted on a hub, and two bearings providing support for the shaft system. The fixed shaft includes a shaft body and a disc flange. The rotating shaft is sleeved on the outside of the shaft body of the fixed shaft. Disc I and disc II are sleeved on the rotating shaft. Disc II is located at one end of the rotating shaft near the disc flange, and disc I is located in the middle of the rotating shaft. A reinforcing rib I is provided between disc I and disc II, penetrating between the two discs. The side of disc I without the reinforcing rib I engages with the hub. The end face of the disc flange 1 of the fixed shaft away from the shaft body engages with the main frame. The two bearings are respectively disposed on the inner diameters of the rotating shaft at both ends. The outer circular surface of the bearing is interference-fitted with the inner circular surface of the rotating shaft. The inner circular surface of the bearing is interference-fitted with the outer circular surfaces of both ends of the main body of the fixed shaft. The outer circular surface of the disc flange of the fixed shaft near the main body is fitted with a fixed shaft disc, which is engaged with the stator support. A concave structure is provided at the transition between the main body of the fixed shaft and the disc flange. The inner surface of the concave structure adopts multiple arcs with an inner radius R greater than 50°, and the multiple arcs are smoothly transitioned. A transition ring is provided in the concave structure. The transition ring extends axially to the bearing outside the concave structure. The transition ring is interference-fitted with the bearing. The outer circular surface of the transition ring is interference-fitted with the rotating shaft, and the inner circular surface of the transition ring is clearance-fitted with the fixed shaft.

[0014] The end face of the fixed shaft body away from the disc flange is provided with a multi-functional bearing pressure ring that fits into the flange of the fixed shaft end face. The bearing pressure ring provides axial preload for the bearing, ensuring the safe and stable operation of the bearing.

[0015] A brake disc is provided on the end face of the rotating shaft away from the disc II, and a brake that cooperates with the brake disc is provided on the bearing pressure ring to realize the braking function of the shaft system.

[0016] The bearing retainer ring is fitted with a brake guard, which provides protection for the brake and brake disc.

[0017] The fixed-axis disk is provided with reinforcing ribs II to increase rigidity;

[0018] Both bearings are single-row tapered roller bearings with an outer diameter greater than 3 meters. The two bearings are of different sizes, and the difference in their outer diameters is less than 100 mm. The bearing span is less than the outer diameter of either bearing. This shortens the axial dimension of the entire shaft system, resulting in a compact structure, light weight, and improved unit economy.

[0019] The inner diameter of the bearing on the side furthest from the fixed-axis disk is smaller than that on the side closest to the fixed-axis disk. When assembling the bearings, with the fixed-axis disk side facing the ground, the downwind bearing is installed first and then moved axially to the transition ring via the shaft end on the side furthest from the fixed-axis disk. This dimension design facilitates bearing installation and reduces assembly difficulty.

[0020] Both ends of the rotating shaft are provided with wedge-shaped seals for sealing bearing grease. The wedge-shaped seals are installed between the fixed shaft and the rotating shaft. When the bearing is working, good lubrication must be ensured. The wedge-shaped seals prevent the loss of bearing grease and provide a guarantee for good bearing lubrication.

[0021] The fixed shaft is provided with a grease removal and maintenance hole, and the rotating shaft is provided with a waist-shaped hole for bearing maintenance along the circumferential direction, and the waist-shaped hole is provided with an easily removable cover plate.

[0022] The beneficial effects of this invention are:

[0023] 1. In this invention, two large-sized but unequal single-row tapered roller bearings are selected, and an outer ring rotating structure is adopted. Compared with the traditional inner ring rotating structure, the outer ring rotating structure has a stronger load-bearing capacity for the same bearing size and bearing span. This not only meets the usage requirements of large MW units, but also further reduces costs and improves the safety and economy of the structure.

[0024] 2. In this invention, the shaft system structure near the rotating disk I is located inside the hub, which makes reasonable use of the internal space of the hub, making the unit structure more compact, greatly shortening the installation distance from the hub center to the main frame, reducing the force generated by the blade load on the yaw bearing, and making the entire unit structure more compact, lower in cost, and more economical.

[0025] 3. In this invention, the rotating shaft adopts a double-disc shared reinforcing rib I structure. This structure is simple, lightweight, and highly rigid. Under wind load, its deformation is small, ensuring the safe and stable operation of the bearing. Simultaneously, it reduces the air gap deformation of the generator, lowers the risk of stator-rotor rubbing, and improves the air gap stability. Furthermore, it increases the uniformity of the air gap, reducing the risk of generator vibration caused by air gap unevenness. Alternatively, during generator design, the air gap value can be further reduced while meeting electromagnetic performance requirements, decreasing the amount of effective materials such as copper and magnets used, thus improving the generator's economy.

[0026] 4. In this invention, the transition between the fixed shaft body and the flange disc structure adopts a concave structure with a multi-segment large-radius smooth arc transition, and a transition ring is set at the concave structure. Due to the sudden change in cross-section at the transition between the fixed shaft body and the flange disc structure, stress concentration will occur under wind load. A large stress concentration factor will lead to excessive stress in the shaft system. Traditional methods to reduce the stress concentration factor, such as using fillets and smooth transition curves, result in a smaller stress concentration factor with a larger fillet radius and a smoother transition. The ingenuity of this invention lies in the use of a concave multi-segment large-radius smooth arc transition structure with a transition ring, which reduces the stress concentration factor of the shaft system structure while providing axial support for the bearing, ensuring the basic function of the shaft system structure. Using only a concave multi-segment large-radius smooth arc transition structure can reduce the stress concentration factor of the shaft system, but it cannot provide axial support for the bearing, and cannot guarantee the stable operation of the bearing. Using a concave small-radius structure design can satisfy the function of providing axial support for the bearing, but it cannot effectively reduce the stress concentration factor. Therefore, the ingenious design of this structure not only ensures that the stress level of the shaft system meets the requirements, but also provides effective support for the bearings, thus meeting the usage requirements of large MW-class units.

[0027] 5. In this invention, the shaft system structure adopts a highly integrated design. A locking seat is designed on the second disc of the rotating shaft, and multiple locking seats are evenly arranged circumferentially on the second disc of the rotating shaft. Under the action of the hydraulic system, the locking pin extends axially to the locking seat, realizing the locking function of the unit. Simultaneously, a brake disc for braking the unit is provided on the side of the rotating shaft near the hub, along with a brake engaged on the bearing pressure ring. Under the action of the hydraulic system, the brake pads and brake disc engage through friction braking, realizing the braking function of the unit.

[0028] 6. The shaft system structure of this invention employs a two-large bearing design with an outer ring rotating structure, resulting in strong bearing load capacity and meeting the requirements of high-power units. The rotating shaft adopts a double-disc single-reinforcing-rib I structure, significantly improving the overall rigidity of the shaft system, reducing the deformation of the unit under wind loads, enhancing the air gap stability of the generator, reducing the risk of stator-rotor rubbing, and ensuring a more uniform air gap, thus reducing vibration risk. Furthermore, it reduces the use of effective materials such as generator magnets and copper, greatly improving the unit's economy. The stator shaft adopts a concave structure with a larger radius (R) in the transition ring, reducing the stress concentration factor of the shaft system and meeting the requirements of large MW-level units. Furthermore, locking and braking structures are centrally designed into the shaft system structure, resulting in a compact overall unit structure. Attached Figure Description

[0029] Figure 1 is a schematic diagram of the main shaft system of the wind turbine generator in this invention.

[0030] Figure 2 is a schematic diagram of the concave structure of the wind turbine main shaft system in this invention.

[0031] Figure 3 is a schematic diagram of the braking structure of the wind turbine main shaft system in this invention.

[0032] Among them, 1. fixed shaft; 2. rotating shaft; 3. bearing; 4. main frame; 5. hub; 6. stator support; 7. disc I; 8. disc II; 9. shaft body; 10. disc flange; 11. reinforcing rib I; 12. concave structure; 13. transition ring; 14. bearing pressure ring; 15. brake disc; 16. brake; 17. wedge seal; 18. brake guard. Embodiments of the present invention

[0033] 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.

[0034] Example 1

[0035] As shown in Figures 1-3, this embodiment provides a wind turbine main shaft system, including a fixed shaft 1 mounted on a main frame 4, a rotating shaft 2 mounted on a hub 5, and two bearings 3 providing support for the shaft system. The fixed shaft 1 includes a shaft body 9 and a disc flange 10. The rotating shaft 2 is sleeved on the outside of the shaft body 9 of the fixed shaft 1. The rotating shaft 2 is sleeved with a disc I7 and a disc II8. The disc II8 is located at one end of the rotating shaft 2 near the disc flange 10, and the disc I7 is located in the middle of the rotating shaft 2. A reinforcing rib I11 is provided between the disc I7 and the disc II8, penetrating between the two discs. The side of the disc I7 without the reinforcing rib I11 is engaged with the hub 5. The end face of the disc flange 10 of the fixed shaft 1 away from the shaft body 9 is engaged with the main frame 4. The two bearings 3 are respectively mounted on the rotating shaft 1. The inner circular surfaces at both ends of shaft 2 and the outer circular surface of bearing 3 are interference-fitted with the inner circular surface of shaft 2. The inner circular surface of bearing 3 is interference-fitted with the outer circular surfaces at both ends of the shaft body 9 of fixed shaft 1. The outer circular surface of the disc flange 10 of fixed shaft 1 near the shaft body 9 is fitted with a fixed shaft disc, which is engaged with stator bracket 6. A concave structure 12 is provided at the transition between the shaft body 9 of fixed shaft 1 and the disc flange 10. The inner surface of the concave structure 12 adopts multiple arcs with an inner radius R greater than 50°, and the multiple arcs are smoothly transitioned. A transition ring 13 is provided in the concave structure 12. The transition ring 13 extends axially to the bearing 3 outside the concave structure. The transition ring 13 is interference-fitted with bearing 3. The outer circular surface of the transition ring 13 is interference-fitted with shaft 2, and the inner circular surface of the transition ring 13 is clearance-fitted with fixed shaft 1.

[0036] In this embodiment, the main shaft system adopts an outer ring rotating structure. With the same main shaft dimensions and bearing span, the outer ring rotating structure has a stronger load-bearing capacity, meeting the requirements of large MW units. The rotating shaft 2 adopts a structure with two discs sharing a common reinforcing rib I11, resulting in a strong overall rigidity of the shaft system, a simple structure, light weight, and good economic efficiency. The transition between the main body of the fixed shaft 1 and the flange disc structure adopts a multi-segment large-R smooth arc transition concave structure 12, and a transition ring 13 is set at the concave structure 12. While meeting the structural requirements, this significantly reduces the stress concentration factor of the fixed shaft 1, meeting the requirements of large MW units.

[0037] The wind turbine main shaft system is a crucial component in converting wind energy into electrical energy. During operation, wind loads are transmitted through the blades and hub 5 to the rotating shaft 2, and then through bearings 3 to the fixed shaft 1 and main frame 4. The wind loads drive the rotating components of the generator, completing the conversion of mechanical energy into electrical energy at the air gap. The rotating shaft 2 provides support for the hub 5, rotor support, and other rotating components, while also bearing the wind load. The fixed shaft 1, mounted on the main frame 4, provides support for the generator stator support 6 and bearings 3. Two single-row tapered roller bearings are located between the fixed shaft 1 and the rotating shaft 2, ensuring the shaft's rotational accuracy and reducing friction and wear between the rotating and stationary components. The wind turbine main shaft system not only bears the wind load but also provides support for all generator components, making it a vital part of the wind turbine unit.

[0038] Example 2

[0039] Compared with Embodiment 1, the difference in this embodiment is that, in this embodiment, the end face of the main body 9 of the fixed shaft 1 away from the disc flange 10 is provided with a multi-functional bearing pressure ring 14 that fits into the end face flange of the fixed shaft 1, and the rest of the structure is the same as in Embodiment 1.

[0040] In this embodiment, the bearing pressure ring 14 provides axial preload for the bearing, ensuring the safe and stable operation of the bearing.

[0041] Example 3

[0042] Compared with Embodiment 1, the difference in this embodiment is that, as shown in Figure 3, the end face of the rotating shaft 2 away from the disc II 8 is provided with a brake disc 15 that engages with the rotating shaft 2, and a brake 16 that cooperates with the brake disc 15 is engaged on the bearing pressure ring 14. The rest of the structure is the same as in Embodiment 1.

[0043] In this embodiment, the braking function of the shaft system is realized by setting a brake disc 15 and a brake 16; thereby realizing the braking of the wind turbine generator set.

[0044] Example 4

[0045] Compared with Embodiment 1, the difference in this embodiment is that the fixed-axis disk is provided with a reinforcing rib II to increase rigidity; the rest of the structure is the same as in Embodiment 1.

[0046] In this embodiment, by setting reinforcing rib II on the fixed-axis disk, the rigidity of the fixed-axis disk is increased, thereby meeting the rigidity requirements of the generator set.

[0047] Example 5

[0048] Compared with Embodiment 1, the difference in this embodiment is that in this embodiment, all bearings 3 are single-row tapered roller bearings, the outer diameter of the two bearings 3 is greater than 3 meters, the two bearings 3 are different in size, and the difference in the outer diameter of the two bearings 3 is less than 100 mm, and the span of the bearings 3 is less than the outer diameter of any one of the bearings 3; the inner diameter of the bearing 3 on the side away from the fixed axis disk is smaller than the inner diameter of the bearing 3 on the side closer to the fixed axis disk, and the rest of the structure is the same as in Embodiment 1.

[0049] In this embodiment, the axial dimension of the entire shaft system is shortened by the structure of bearing 3, resulting in a compact structure and light weight, which improves the economic efficiency of the unit. When assembling bearing 3, the fixed shaft disk side faces the ground. First, the downwind bearing 3 is installed and then moved axially to the transition ring 13 by the shaft end away from the shaft disk side. This size design facilitates the installation of bearing 3 and reduces the assembly difficulty.

[0050] Example 6

[0051] The difference between this embodiment and Embodiment 1 is that, in this embodiment, wedge-shaped seals 17 for sealing bearing grease are provided at both ends of the rotating shaft 2, and the wedge-shaped seals 17 are installed between the fixed shaft 1 and the rotating shaft 2. The rest of the structure is the same as in Embodiment 1.

[0052] In this embodiment, when the bearing 3 is working, good lubrication must be ensured. By setting a wedge seal to prevent the loss of grease from the bearing 3, good lubrication of the bearing 3 is guaranteed.

[0053] Example 7

[0054] Compared with Embodiment 1, the difference in this embodiment is that the bearing pressure ring 14 is fitted with a brake protective cover 18, the fixed shaft 1 is provided with a grease removal and maintenance hole, the rotating shaft 2 is provided with a waist-shaped hole for the maintenance of the bearing 3 along the circumferential direction, and the waist-shaped hole is provided with an easily removable cover plate; the rest of the structure is the same as that in Embodiment 1.

[0055] In this embodiment, a brake guard 18 is provided to protect the brake 16 and brake disc 15, preventing foreign objects from entering and causing damage to the brake components and brake disc 15. The waist-shaped hole is located at the oil chamber baffle of the rotating shaft 2. By providing a grease removal maintenance hole and a waist-shaped hole, the maintenance of the shaft system is facilitated. An easily removable cover plate is provided on the waist-shaped hole, which is convenient to open and close during maintenance.

[0056] 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 wind turbine main shaft system, characterized in that: The shaft system includes a fixed shaft (1) mounted on the main frame (4), a rotating shaft (2) mounted on the hub (5), and two bearings (3) providing support for the shaft system. The fixed shaft (1) includes a shaft body (9) and a disc flange (10). The rotating shaft (2) is sleeved on the outside of the shaft body (9) of the fixed shaft (1). The rotating shaft (2) is sleeved with a disc I (7) and a disc II (8). The disc II (8) is located on the rotating shaft (2) near the disc flange (10). At one end, disk I (7) is located in the middle of the rotating shaft (2). A reinforcing rib I (11) is provided between disk I (7) and disk II (8) and passes through the two disks. The side of disk I (7) without the reinforcing rib I (11) is engaged with the hub (5). The end face of the disk flange (10) of the fixed shaft (1) away from the shaft body (9) is engaged with the main frame (4). Two bearings (3) are respectively set at the inner ends of the rotating shaft (2). The outer circular surface of the bearing (3) is press-fitted with the inner circular surface of the rotating shaft (2). The inner circular surface of the bearing (3) is press-fitted with the outer circular surfaces of both ends of the shaft body (9) of the fixed shaft (1). The outer circular surface of the disc flange (10) of the fixed shaft (1) near the shaft body (9) is fitted with a fixed shaft disc. The fixed shaft disc is engaged with the stator bracket (6). A concave structure is provided at the transition between the shaft body (9) and the disc flange (10) of the fixed shaft (1). 12) The inner surface of the concave structure (12) is made of multiple arcs with an inner radius R greater than 50°. The multiple arcs are smoothly transitioned. A transition ring (13) is provided in the concave structure (12). The transition ring (13) extends axially to the bearing (3) outside the concave structure. The transition ring (13) is interference-fitted with the bearing (3). The outer circle of the transition ring (13) is interference-fitted with the rotating shaft (2). The inner circle of the transition ring (13) is clearance-fitted with the fixed shaft (1).

2. The wind turbine main shaft system according to claim 1, characterized in that: The end face of the fixed shaft (1) main body (9) away from the disc flange (10) is provided with a bearing pressure ring (14) that engages with the flange of the fixed shaft (1) end face.

3. The wind turbine main shaft system according to claim 2, characterized in that: The end face of the rotating shaft (2) away from the disc II (8) is provided with a brake disc (15) that engages with the rotating shaft (2), and a brake (16) that cooperates with the brake disc (15) is engaged on the bearing pressure ring (14).

4. The wind turbine main shaft system according to claim 3, characterized in that: The bearing ring (14) is fitted with a brake guard (18).

5. The wind turbine main shaft system according to claim 1, characterized in that: The fixed-axis disk is provided with reinforcing ribs II to increase rigidity.

6. The wind turbine main shaft system according to claim 1, characterized in that: Both bearings (3) are single-row tapered roller bearings. The outer diameter of the two bearings (3) is greater than 3 meters. The two bearings (3) are different in size, and the difference in the outer diameter of the two bearings (3) is less than 100 mm. The span of the bearings (3) is less than the outer diameter of any one of the bearings (3).

7. A wind turbine main shaft system according to claim 6, characterized in that: The inner diameter of the bearing (3) on the side away from the fixed-axis disk is smaller than the inner diameter of the bearing (3) on the side closer to the fixed-axis disk.

8. The wind turbine main shaft system according to claim 1, characterized in that: Both ends of the rotating shaft (2) are provided with wedge-shaped seals (17) for sealing bearing grease, and the wedge-shaped seals (17) are installed between the fixed shaft (1) and the rotating shaft (2).

9. A wind turbine main shaft system according to claim 1, characterized in that: The fixed shaft (1) is provided with a grease removal and maintenance hole, and the rotating shaft (2) is provided with a waist-shaped hole for bearing (3) maintenance along the circumferential direction. The waist-shaped hole is provided with an easily removable cover plate.

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