Wind turbine pitch reducer and its design method

Abstract

A wind turbine pitch reducer includes a housing, an input shaft housed within the housing, a multi-stage planetary reduction gear assembly housed within the housing and meshing with the input shaft, and an output shaft meshing with the output end of the multi-stage planetary reduction gear assembly. The output shaft extends from the housing. The invention is characterized by: multiple rows of ball bearings arranged axially from top to bottom between the output shaft and the housing, which axially position the output shaft on the housing and form a rotational connection between the output shaft and the housing; and a multi-layer sealing assembly that seals and separates the multi-stage planetary reduction gear assembly and the ball bearings, and seals the bottom end of the housing. This invention effectively reduces the size of the pitch reducer's output end, improves the load-bearing capacity and support rigidity of the output shaft, prevents overturning, reduces the wear rate of internal gears and bearings in the pitch reducer, extends service life, and improves the sealing effect of the reducer's output end. This invention also provides a design method for a wind turbine pitch reducer.

Description

Technical Field

[0001] This invention relates to a wind turbine pitch reducer, belonging to the technical field of wind turbine pitch reducers. Background Technology

[0002] In wind turbine generator sets, the pitch control system plays a crucial role in adjusting the blade angle of the wind turbine and ensuring stable and efficient operation of the unit under different wind speeds. The pitch reducer is a key transmission component in the pitch control system, converting the high-speed, low-torque of the drive motor into low-speed, high-torque driving the blade root bearings to adjust the direction and angle of the wind turbine blades. Currently, pitch reducers mostly employ multi-stage planetary gear transmissions, with the output shaft connected to the final stage planetary carrier. Double self-aligning roller bearings or double tapered roller bearings are arranged on the output shaft to form support between the output shaft and the reducer housing. Axial positioning of the output shaft is achieved through the cooperation of a round nut fastened to the output shaft and the roller bearings. The output shaft's transmission characteristics are low speed and high torque, requiring the output shaft and roller bearings to withstand axial and radial loads. However, the support and positioning structure of the output shaft has the following defects:

[0003] 1. Roller bearings have large axial and radial dimensions, occupy a large space in the wind turbine hub, have high requirements for hub assembly space, poor adaptability, and require clearance adjustment to ensure the bearing reaches the optimal working condition. This results in high processing and assembly requirements, leading to larger output dimensions and higher assembly costs for the pitch reducer.

[0004] 2. Roller bearings have high lubrication requirements, and the seal between the output end and the housing is weak. Iron filings formed by the wear of multi-stage planetary gears during operation can easily enter the upper roller bearings, affecting their performance and service life. The reducer also has the risk of oil leakage.

[0005] 3. Under harsh working conditions, the reducer is prone to shaking. Increased output shaft diameter and axial load can lead to misalignment. Due to insufficient load-bearing capacity, the output shaft will experience bending moment deformation and axial impact, which will affect the multi-stage planetary gears inside the reducer, accelerate gear wear, reduce the stability of the reducer, and even cause the reducer to overturn.

[0006] 4. The tightening torque of the round nut needs to be above 2500Nm, requiring special high-torque tightening tools and equipment. Moreover, the tightened round nut is at risk of loosening during the operation of the reducer. If the round nut is loose, it will move axially on the output shaft, affecting the stability of the axial positioning of the output shaft. Summary of the Invention

[0007] The wind turbine pitch reducer provided by this invention can effectively reduce the size of the pitch reducer output end, improve the compatibility between the pitch reducer output end and the impeller hub, increase the load-bearing capacity and support rigidity of the output shaft, improve the stability of the pitch reducer and prevent overturning, improve the axial positioning reliability of the output shaft, reduce the wear rate of the internal gears and bearings of the pitch reducer, extend their service life, improve the sealing effect of the reducer output end, and ensure the lubrication reliability of the multi-row reduction components and multi-row ball bearings. This invention also provides a design method for the wind turbine pitch reducer.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A wind turbine pitch reducer includes a housing, an input shaft mounted in the housing, a multi-stage planetary reduction gear assembly mounted in the housing and meshing with the input shaft, and an output shaft meshing with the output end of the multi-stage planetary reduction gear assembly. The output shaft extends out of the housing. The characteristic feature is that multiple rows of ball bearings are installed between the output shaft and the housing, arranged axially from top to bottom. These multiple rows of ball bearings axially position the output shaft on the housing and form a rotatable connection between the output shaft and the housing. A multi-layer sealing assembly is installed between the output shaft and the housing to seal and separate the multi-stage planetary reduction gear assembly and the multiple rows of ball bearings, and to seal the bottom end of the housing.

[0010] Preferably, the multi-stage planetary reduction gear assembly includes a first-stage sun gear meshing with the input shaft, a first-stage planet gear meshing with the first-stage sun gear, a first-stage planet carrier connected to the first-stage planet gear, a second-stage sun gear meshing with the first-stage planet carrier, a second-stage planet gear meshing with the second-stage sun gear, a second-stage planet carrier connected to the second-stage planet gear, a final-stage sun gear meshing with the second-stage planet carrier, a final-stage planet gear meshing with the final-stage sun gear, and a final-stage planet carrier connected to the final-stage planet gear. The first-stage planet gear, the second-stage planet gear, and the final-stage planet gear mesh with a gear ring on the inner wall of the gearbox. The upper end of the output shaft meshes with the final-stage planet carrier. Multiple rows of ball bearings and a multi-layer sealing assembly are disposed below the final-stage planet carrier.

[0011] Preferably, the output shaft is integrally formed from top to bottom by an upper gear segment meshing with the final stage planetary carrier, an intermediate mating segment, and a lower gear segment extending out of the housing. Multiple rows of balls and multi-layer sealing components are disposed between the inner wall of the housing and the intermediate mating segment. An annular raceway is formed between the intermediate mating segment and the inner wall of the housing. The annular raceway is evenly spaced along the axial direction. The multiple rows of balls are composed of balls installed in the annular raceway. The balls in the annular raceway are arranged sequentially to form a row of balls. Each ball forms four contact points with the annular raceway in a rectangular distribution.

[0012] Preferably, an inner wall raceway is formed on the inner wall of the housing, and an output shaft raceway corresponding to the inner wall raceway is formed on the intermediate mating shaft. There is a radial gap between the intermediate mating section and the inner wall of the housing to separate the inner wall raceway and the corresponding output shaft raceway from contact. The inner wall raceway and the corresponding output shaft raceway are radially aligned to form an annular raceway. The ball is sandwiched between the inner wall raceway and the corresponding output shaft raceway, and the ball forms two contact points with the inner wall raceway and the output shaft raceway, respectively.

[0013] Preferably, both the inner wall raceway and the output shaft raceway are formed by connecting two annular arc surfaces with circular arc cross-sections, and the two annular arc surfaces respectively contact the ball forming point.

[0014] Preferably, the multi-layer sealing assembly includes at least an upper oil seal disposed above the multiple rows of balls and a lower oil seal disposed below the multiple rows of balls.

[0015] Preferably, the inner cavity of the housing is divided into an upper cavity above the upper oil seal and a lower cavity between the upper and lower oil seals. The upper cavity contains lubricating oil for lubricating the multi-stage planetary reduction gear assembly, and the lower cavity is filled with grease for lubricating the multi-row ball bearings.

[0016] Preferably, the housing consists of an upper housing and a lower housing coaxially fixed to the bottom of the upper housing. Multiple rows of ball bearings and multi-layer sealing components are respectively installed between the lower housing and the output shaft. The inner cavity of the lower housing includes a gear ring cavity that meshes with the last stage planetary gear, an assembly cavity for assembling multiple rows of ball bearings and multi-layer sealing components, and a wedge-shaped transition cavity disposed between the gear ring cavity and the assembly cavity. The inner diameter of the assembly cavity is smaller than the inner diameter of the gear ring cavity. The wedge-shaped transition cavity is wedge-shaped with a diameter that gradually decreases from top to bottom. The top of the assembly cavity is provided with an upper annular step surface that mates with the upper oil seal, and the bottom of the assembly cavity is provided with a lower annular step surface that mates with the lower oil seal. The upper oil seal abuts against the upper annular step surface, and the lower oil seal abuts against the lower annular step surface. An axial retaining ring that supports the lower oil seal is installed in the assembly cavity.

[0017] The design method of the wind turbine pitch reducer described above is characterized by: designing the number of rows of balls, the diameter of the balls, and the number of balls in each row according to the radial load, axial load, and torque transmission requirements of the output shaft.

[0018] Preferably, the number of layers and the axial position of each layer of the multi-layer sealing assembly are designed according to the number of rows of multi-row balls, lubrication requirements, and sealing requirements of the housing.

[0019] The beneficial effects of the invention are:

[0020] The wind turbine pitch reducer of the present invention has multiple rows of ball bearings installed between the output shaft and the housing. The multiple rows of ball bearings axially position the output shaft on the housing and form a rotatable connection between the output shaft and the housing. The multiple rows of ball bearings replace the roller bearings between the housing and the output shaft in the prior art. The axial and radial dimensions occupied by the multiple rows of ball bearings between the output shaft and the housing are small, which can effectively reduce the size of the output end of the pitch reducer and improve the compatibility between the output end of the pitch reducer and the impeller hub.

[0021] The number of rows of balls, the diameter of the balls, and the number of balls in each row can be set according to the load requirements of the output shaft, thereby improving the load-bearing capacity and support rigidity of the output shaft, adapting to the load requirements of harsh working conditions, ensuring that the output shaft is set along the axial direction of the reducer without deviation, reducing the impact on the internal structure of the reducer, improving the stability of the pitch reducer, and preventing overturning.

[0022] Using multiple rows of ball bearings to form the axial positioning of the output shaft on the housing, instead of the axial positioning structure where a round nut is fastened to the output shaft, not only eliminates the need for tightening the round nut, but also improves the reliability of the axial positioning of the output shaft, reduces the impact of the output shaft on the multi-stage planetary reduction assembly during operation, reduces the wear rate of the gears and bearings inside the pitch reducer, and extends its service life.

[0023] A multi-layer sealing assembly is installed between the output shaft and the housing. This assembly seals and separates the multi-stage planetary reducer assembly and the multi-row ball bearings, and seals the bottom of the housing. It also seals and separates the chamber containing the multi-stage planetary reducer assembly from the chamber containing the multi-row ball bearings. The multi-row ball bearings and the multi-stage reducer assembly are lubricated independently, preventing iron filings generated by gear wear during the operation of the multi-stage planetary reducer assembly from falling into the multi-stage ball bearings. The multi-layer sealing assembly improves the sealing effect at the output end of the reducer and ensures the reliability of lubrication for the multi-stage reducer assembly and the multi-row ball bearings. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the wind turbine pitch reducer of the present invention.

[0025] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0026] Figure 3 This is a schematic diagram of the output shaft.

[0027] Figure 4 This is a schematic diagram of the lower housing. Detailed Implementation

[0028] The following is combined Figures 1 to 4 The embodiments of the present invention will be described in detail below.

[0029] A wind turbine pitch reducer includes a housing 1, an input shaft 2 mounted in the housing 1, a multi-stage planetary reduction gear assembly 3 mounted in the housing 1 and meshing with the input shaft 1, and an output shaft 4 meshing with the output end of the multi-stage planetary reduction gear assembly 3. The output shaft 4 extends out of the housing 1. The characteristic feature is that a multi-row ball bearing 5 is installed between the output shaft 4 and the housing 1, arranged in multiple rows from top to bottom along the axial direction. The multi-row ball bearing 5 axially positions the output shaft 4 on the housing 1 and forms a rotatable connection between the output shaft 4 and the housing 1. A multi-layer sealing assembly 6 is installed between the output shaft 4 and the housing 1 to seal and separate the multi-stage planetary reduction gear assembly 3 and the multi-row ball bearing 5 and to seal the bottom end of the housing 1.

[0030] The wind turbine pitch reducer described above has multiple rows of ball bearings 5 ​​installed between the output shaft 4 and the housing 1. These multiple rows of ball bearings 5 ​​axially position the output shaft 4 on the housing 1, forming a rotational connection between the output shaft 4 and the housing 1. Replacing the roller bearings between the housing and the output shaft in existing technologies with multiple rows of ball bearings 5 ​​results in smaller axial and radial dimensions between the output shaft 4 and the housing 1, effectively reducing the size of the pitch reducer's output end and improving its compatibility with the impeller hub. The number of rows, ball diameter, and number of balls per row of the multiple rows of ball bearings 5 ​​can be set according to the load-bearing requirements of the output shaft 4, improving the output shaft's load-bearing capacity and support rigidity, adapting to harsh operating conditions, ensuring the output shaft remains aligned axially along the reducer, reducing the impact on the internal structure of the reducer, improving the stability of the pitch reducer, and preventing overturning. The output shaft 4 is axially positioned on the housing 1 using multiple rows of ball bearings 5, replacing the axial positioning structure where a round nut is fastened to the output shaft. This not only eliminates the need for tightening the round nut but also improves the reliability of the axial positioning of the output shaft 4, reduces the impact of the output shaft on the multi-stage planetary reduction assembly 3 during operation, reduces the wear rate of gears and bearings inside the pitch reducer, and extends its service life. A multi-layer sealing assembly 6 is installed between the output shaft 4 and the housing 1. The multi-layer sealing assembly 6 seals and separates the multi-stage planetary reduction assembly 3 and the multiple rows of ball bearings 5, and seals the bottom of the housing 1. It also seals and separates the chamber containing the multi-stage planetary reduction assembly 3 from the chamber containing the multiple rows of ball bearings 5. The multiple rows of ball bearings 5 ​​and the multi-stage reduction assembly 3 are lubricated independently, preventing iron filings generated by gear wear during the operation of the multi-stage planetary reduction assembly 3 from falling into the multiple rows of ball bearings 5. The multi-layer sealing assembly 6 improves the sealing effect at the output end of the reducer and ensures the lubrication reliability of the multi-stage reduction assembly and the multiple rows of ball bearings.

[0031] The multi-stage planetary reduction assembly 3 includes a first-stage sun gear 31 meshing with the input shaft 2, a first-stage planetary gear 32 meshing with the first-stage sun gear 31, a first-stage planetary carrier 33 connected to the first-stage planetary gear 32, a second-stage sun gear 34 meshing with the first-stage planetary carrier 33, a second-stage planetary gear 35 meshing with the second-stage sun gear 34, a second-stage planetary carrier 36 connected to the second-stage planetary gear 35, a final-stage sun gear 37 meshing with the second-stage planetary carrier 36, a final-stage planetary gear 38 meshing with the final-stage sun gear 37, and a final-stage planetary carrier 39 connected to the final-stage planetary gear 38. The first-stage planetary gear 32, the second-stage planetary gear 35, and the final-stage planetary gear 38 respectively mesh with gear rings on the inner wall of the housing 1. The upper end of the output shaft 4 meshes with the final-stage planetary carrier 39. Multiple rows of ball bearings 5 ​​and a multi-layer sealing assembly 6 are arranged below the final-stage planetary carrier 39. The multi-stage planetary reducer assembly 3 includes a three-stage planetary gear structure. The final stage planetary carrier 39 is located above the multi-row ball bearings 5 ​​and the multi-layer sealing assembly 6. The multi-row ball bearings 5 ​​and the multi-layer sealing assembly 6 are respectively assembled between the output shaft 4 and the inner wall of the housing 1. The multi-layer sealing assembly 6 seals and separates the multi-stage planetary reducer assembly 3 from the multi-row ball bearings 5, seals the chamber where the multi-row ball bearings 5 ​​are located, and forms a multi-layer seal on the bottom of the housing 1. This allows the multi-stage planetary reducer assembly 3 and the multi-row ball bearings 5 ​​to be lubricated independently, improving lubrication reliability and effectively reducing the risk of oil leakage.

[0032] The output shaft 4 is integrally formed from top to bottom by an upper gear section 41 that meshes with the final stage planetary carrier 39, an intermediate mating section 42, and a lower gear section 43 that extends out of the housing 1. Multiple rows of balls 5 and a multi-layer sealing assembly 6 are disposed between the inner wall of the housing 1 and the intermediate mating section 42. An annular raceway 7 is formed between the intermediate mating section 42 and the inner wall of the housing 1. The annular raceway 7 is evenly spaced along the axial direction. The multiple rows of balls 5 are composed of balls 51 installed in the annular raceway. The balls 51 in the annular raceway 7 are arranged in sequence to form a row of balls. Each ball 51 forms four contact points with the annular raceway 7 in a rectangular distribution. The annular raceway 7 is formed on the inner wall of the intermediate mating section 42 and the housing 1. The intermediate mating section 42 and the housing 1 serve as the inner and outer rings of the bearing, eliminating the need for separate inner and outer rings. The assembly structure of the balls 51 with the intermediate mating section 42 and the housing 1 replaces the bearing, reducing the weight and size of the assembly structure between the output shaft 4 and the housing 1. The balls 51 and the annular raceway 7 form four rectangular contact points. The multiple rows of balls 5 are equivalent to a multi-row four-point contact bearing. The cooperation between the multiple rows of balls 5 and the output shaft and housing provides axial positioning and radial support for the output shaft 4, improving the positioning reliability and load-bearing capacity of the output shaft 4, increasing its support stiffness and load-bearing capacity, and enhancing its bending moment resistance. This effectively reduces the probability of bending moment deformation of the output shaft 4 under harsh working conditions. The balls 51 in the annular raceway 7 are arranged sequentially to form a row of balls, with no spacers between adjacent balls 51. The annular raceway 7 can achieve full filling of balls 51, resulting in a larger number of balls, simpler assembly, and higher load-bearing capacity.

[0033] In this configuration, an inner wall raceway A is formed on the inner wall of the housing 1, and an output shaft raceway B corresponding to the inner wall raceway A is formed on the intermediate mating shaft 42. A radial gap C exists between the intermediate mating section 42 and the inner wall of the housing 1 to separate the inner wall raceway A and the corresponding output shaft raceway B from contact. The inner wall raceway A and the corresponding output shaft raceway B are radially aligned to form an annular raceway 7. A ball bearing 51 is sandwiched between the inner wall raceway A and the corresponding output shaft raceway B, and the ball bearing 51 forms two contact points with the inner wall raceway A and the output shaft raceway B, respectively. There is a radial clearance C between the inner wall raceway A and the corresponding output shaft raceway B. The ball 51 is sandwiched between the inner wall raceway A and the output shaft raceway B, and forms two contact points with the inner wall raceway A and the output shaft raceway B respectively, forming a four-point contact between the ball 51 and the annular raceway 7. Only corresponding raceways need to be opened on the intermediate mating section 42 and the inner wall of the housing 1. The ball 51 is assembled in place when it is inserted between the inner wall raceway A and the output raceway B, which simplifies the assembly structure between the output shaft 4 and the housing 1, reduces the number of assembly parts, and thus reduces the failure rate. The ball 51 is positioned by the inner wall raceway A and the corresponding output shaft raceway B, which ensures the reliability of the axial positioning of the ball 51 between the output shaft 4 and the housing 1. The axial positioning, radial support and rotational connection of the output shaft 4 with the annular raceway 7 are achieved by the cooperation of the ball 51 and the annular raceway 7, which effectively simplifies the internal structure of the pitch reducer and improves the load-bearing capacity and support rigidity.

[0034] The inner wall raceway A and the output shaft raceway B are both formed by connecting two annular arc surfaces D with circular arc cross-sections, and each of the two annular arc surfaces D forms a point contact with the ball 5. As shown in the figure, the inner wall raceway A and the output raceway B are flared shapes arranged opposite each other. The two annular arc surfaces D are arranged opposite each other and connected at their ends to form the inner wall raceway A and the output raceway B. Each annular arc surface D forms a contact point with the ball 51, so that the annular raceway 7 and the ball 51 form four contact points distributed in a rectangle, forming a four-point contact.

[0035] The multi-layer sealing assembly 6 includes at least an upper oil seal 61 positioned above the multi-row ball bearings 5 ​​and a lower oil seal 62 positioned below the multi-row ball bearings 5. Since the multi-layer sealing assembly 6 is positioned below the final planetary carrier 39, the upper oil seal 61 is located between the multi-row ball bearings 5 ​​and the final planetary carrier 39, sealingly separating the chamber containing the multi-stage planetary reduction assembly 3 from the chamber containing the multi-row ball bearings 5. The lower oil seal 62 seals the chamber containing the multi-row ball bearings 5, allowing the multi-stage planetary reduction assembly 3 and the multi-row ball bearings 5 ​​to be lubricated separately. As shown in the figure, the multi-row ball bearings 5 ​​between the output shaft 4 and the housing 1 consist of two rows of ball bearings. The upper oil seal 61 is positioned above the multi-row ball bearings 5, and the lower oil seal 62 is positioned below, forming... The independent sealed chambers of the multi-row ball bearings 5 ​​not only seal the chamber where the multi-row ball bearings 5 ​​are located, but also seal and separate the multi-row ball bearings 5 ​​from the multi-stage planetary reduction assembly 3. This prevents iron filings formed by the wear of the multi-stage planetary reduction assembly 3 from falling into the multi-row ball bearings 5. At the same time, it forms a multi-layer seal on the bottom of the housing. If the number of rows of multi-row ball bearings 5 ​​is increased, the number of layers of the multi-layer sealing assembly 6 can be increased. A sealing layer is also set in the multi-row ball bearings 5 ​​to divide the chamber where the multi-row ball bearings 5 ​​are located into multiple independent sealed chambers to ensure that each row of ball bearings can be fully lubricated.

[0036] The housing 1 is divided into an upper cavity E above the upper oil seal 61 and a lower cavity F between the upper oil seal 61 and the lower oil seal 62. The upper cavity E contains lubricating oil for lubricating the multi-stage planetary reducer assembly 3, while the lower cavity F contains grease for lubricating the multi-row ball bearings 5. The oil in the upper cavity E lubricates the multi-stage planetary reducer assembly 3, while the grease in the lower cavity F lubricates the multi-row ball bearings 5, thus separating the lubrication of the multi-stage planetary reducer assembly 3 and the multi-row ball bearings 5. The grease also prevents leakage of the lubricating oil in the upper cavity E, improves sealing efficiency, and ensures that the multi-stage planetary reducer assembly 3 and the multi-row ball bearings 5 ​​are adequately lubricated.

[0037] The housing 1 consists of an upper housing 8 and a lower housing 9 coaxially fixed to the bottom of the upper housing 8. Multiple rows of ball bearings 5 ​​and a multi-layer sealing assembly 6 are respectively installed between the lower housing 9 and the output shaft 4. The inner cavity of the lower housing 9 includes a gear ring cavity 91 that meshes with the final stage planetary gear 38, an assembly cavity 92 for assembling the multiple rows of ball bearings 5 ​​and the multi-layer sealing assembly 6, and a wedge-shaped transition cavity 93 disposed between the gear ring cavity 91 and the assembly cavity 92. The inner diameter of the assembly cavity 92 is smaller than that of the gear ring. The inner diameter of cavity 91, the wedge-shaped transition cavity 93 is wedge-shaped with the diameter gradually decreasing from top to bottom, the top of the assembly cavity 92 is provided with an upper annular step surface 90 that mates with the upper oil seal 61, the bottom of the assembly cavity 92 is provided with a lower annular step surface 94 that mates with the lower oil seal 62, the upper oil seal 61 abuts against the upper annular step surface 90, the lower oil seal 62 abuts against the lower annular step surface 94, and an axial retaining ring 95 that supports the lower oil seal 62 is assembled in the assembly cavity 92. The assembly cavity 92 is fitted with multiple rows of ball bearings 5, and the upper annular step surface 90 forms an axial positioning of the upper oil seal 61. The lower annular step surface 94 and the axial retaining ring 95 form an axial positioning of the lower oil seal 62, so that the multiple rows of ball bearings 5 ​​are sealed in the lower cavity F. The assembly of the multiple rows of ball bearings 5 ​​and the multi-layer sealing assembly 6 in the lower housing 9 is simple, and a sealed chamber is formed for independent lubrication of the multiple rows of ball bearings. While ensuring lubrication of the multiple rows of ball bearings 5, a multi-layer seal is formed on the bottom of the housing 1 to prevent oil leakage.

[0038] This invention also protects the design method of the wind turbine pitch reducer described above, characterized in that: based on the radial load, axial load, and torque transmission requirements of the output shaft 4, the number of rows of ball bearings 5, the ball bearing diameter, and the number of balls in each row are designed. By setting the number of rows of ball bearings 5, the ball bearing diameter, and the number of balls in each row according to the load requirements of the output shaft 4, the load-bearing capacity and support stiffness of the output shaft are improved, adapting to the load-bearing requirements of harsh working conditions, ensuring that the output shaft is not offset along the axial direction of the reducer, reducing the impact on the internal structure of the reducer, improving the stability of the pitch reducer, and preventing overturning.

[0039] The number of layers and the axial position of each layer of the multi-layer sealing assembly 6 are designed according to the number of rows of multi-row ball bearings 5, lubrication requirements, and sealing requirements of the housing 1. The multi-layer sealing assembly 6 forms a seal for the chamber containing the multi-row ball bearings 5 ​​and seals and separates the multi-row ball bearings 5 ​​from the multi-stage planetary reduction assembly 3, preventing iron filings formed by the wear of the multi-stage planetary reduction assembly 3 from falling into the multi-row ball bearings 5. At the same time, it forms a multi-layer seal for the bottom of the housing. Depending on the number of rows of multi-row ball bearings 5, the number of layers of the multi-layer sealing assembly 6 can be increased, and a sealing layer can also be set in the multi-row ball bearings 5, dividing the chamber containing the multi-row ball bearings 5 ​​into multiple independent sealed chambers to ensure that each row of ball bearings can be fully lubricated.

[0040] The technical solutions of the embodiments of the present invention have been fully described above with reference to the accompanying drawings. It should be noted that the described embodiments are only a part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A wind turbine pitch reducer, comprising a housing, an input shaft mounted in the housing, a multi-stage planetary reduction gear assembly mounted in the housing and meshing with the input shaft, and an output shaft meshing with the output end of the multi-stage planetary reduction gear assembly, the output shaft extending out of the housing, characterized in that: The output shaft and the housing are equipped with multiple rows of ball bearings arranged axially from top to bottom. The multiple rows of ball bearings axially position the output shaft on the housing and form a rotatable connection between the output shaft and the housing. A multi-layer sealing assembly is assembled between the output shaft and the housing to seal and separate the multi-stage planetary reduction assembly and the multiple rows of ball bearings and to seal the bottom of the housing. The multi-stage planetary reduction gear assembly includes a first-stage sun gear meshing with the input shaft, a first-stage planet gear meshing with the first-stage sun gear, a first-stage planet carrier connected to the first-stage planet gear, a second-stage sun gear meshing with the first-stage planet carrier, a second-stage planet gear meshing with the second-stage sun gear, a second-stage planet carrier connected to the second-stage planet gear, a final-stage sun gear meshing with the second-stage planet carrier, a final-stage planet gear meshing with the final-stage sun gear, and a final-stage planet carrier connected to the final-stage planet gear. The first-stage planet gear, the second-stage planet gear, and the final-stage planet gear mesh with a gear ring on the inner wall of the gearbox. The upper end of the output shaft meshes with the final-stage planet carrier. Multiple rows of balls and a multi-layer sealing assembly are arranged below the final-stage planet carrier. The output shaft is integrally formed from top to bottom by an upper gear section that meshes with the final stage planetary carrier, an intermediate mating section, and a lower gear section that extends out of the housing. Multiple rows of balls and multiple layers of sealing components are arranged between the inner wall of the housing and the intermediate mating section. An annular raceway is formed between the intermediate mating section and the inner wall of the housing. The annular raceway is evenly spaced along the axial direction. The multiple rows of balls are composed of balls installed in the annular raceway. The balls in the annular raceway are arranged sequentially to form a row of balls. Each ball forms four contact points with the annular raceway in a rectangular distribution. The multi-layer sealing assembly includes at least an upper oil seal disposed above multiple rows of balls and a lower oil seal disposed below multiple rows of balls; The housing consists of an upper housing and a lower housing coaxially fixed to the bottom of the upper housing. Multiple rows of ball bearings and multi-layer sealing assemblies are respectively installed between the lower housing and the output shaft. The inner cavity of the lower housing includes a gear ring cavity that meshes with the last stage planetary gear, an assembly cavity for assembling multiple rows of ball bearings and multi-layer sealing assemblies, and a wedge-shaped transition cavity between the gear ring cavity and the assembly cavity. The inner diameter of the assembly cavity is smaller than the inner diameter of the gear ring cavity. The wedge-shaped transition cavity is wedge-shaped with a diameter that gradually decreases from top to bottom. The top of the assembly cavity is provided with an upper annular step surface that mates with the upper oil seal, and the bottom of the assembly cavity is provided with a lower annular step surface that mates with the lower oil seal. The upper oil seal abuts against the upper annular step surface, and the lower oil seal abuts against the lower annular step surface. An axial retaining ring that supports the lower oil seal is installed in the assembly cavity.

2. The wind turbine pitch reducer according to claim 1, characterized in that: The inner wall of the housing has an inner wall raceway, and the intermediate mating shaft has an output shaft raceway that corresponds one-to-one with the inner wall raceway. There is a radial gap between the intermediate mating section and the inner wall of the housing to separate the inner wall raceway and the corresponding output shaft raceway so that they do not contact each other. The inner wall raceway and the corresponding output shaft raceway are radially aligned to form an annular raceway. The ball is sandwiched between the inner wall raceway and the corresponding output shaft raceway, and the ball forms two contact points with the inner wall raceway and the output shaft raceway, respectively.

3. The wind turbine pitch reducer according to claim 2, characterized in that: The inner wall raceway and the output shaft raceway are both formed by connecting two annular arc surfaces with circular arc cross-sections, and the two annular arc surfaces respectively contact the ball forming point.

4. The wind turbine pitch reducer according to claim 1, characterized in that: The inner cavity of the housing is divided into an upper cavity above the upper oil seal and a lower cavity between the upper and lower oil seals. The upper cavity contains lubricating oil for lubricating the multi-stage planetary reduction gear assembly, and the lower cavity is filled with grease for lubricating the multi-row ball bearings.

5. The design method of the wind turbine pitch reducer according to any one of claims 1 to 4, characterized in that: Based on the radial load, axial load and torque transmission requirements of the output shaft, design the number of rows of balls, the ball diameter and the number of balls in each row.

6. The design method of the wind turbine pitch reducer according to claim 5, characterized in that: The number of layers and the axial position of each layer of the multi-layer sealing assembly are designed based on the number of rows of ball bearings, lubrication requirements, and sealing requirements of the housing.

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