Wind turbine generator variable pitch bearing and hub variable pitch stud maintenance-free structure and installation method
By combining a conical main nut, conical sleeve, and clamping bracket, along with precise robotic installation and segmented rain guard rings, the problem of easy loosening and failure of the pitch studs in the pitch bearing and hub, as well as the high maintenance risk, has been solved, achieving 25 years of maintenance-free operation and reducing maintenance costs and safety hazards.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WINDEY ENERGY TECHNOLOGY GROUP CO LTD
- Filing Date
- 2026-04-23
- Publication Date
- 2026-06-12
AI Technical Summary
The pitch studs of the pitch bearing and hub of the wind turbine are prone to loosening and failure. The bolt maintenance is risky and inefficient, which leads to safety hazards and increased maintenance costs for the unit.
It adopts a combination structure of tapered main nut, tapered sleeve and clamping bracket, and is precisely installed by robot to control the pre-tightening force within ±5%, forming a double anti-loosening guarantee. Combined with segmented rain guard ring to form a sealed cavity, the deflector design is eliminated.
It effectively prevents the pitch stud from loosening within 25 years, reduces maintenance frequency, reduces downtime and costs, and improves unit safety and transportation efficiency.
Smart Images
Figure CN122191004A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wind turbine pitch system technology, and more specifically, to a maintenance-free structure for a wind turbine pitch bearing and hub pitch stud. Furthermore, it also relates to an installation method for the aforementioned maintenance-free structure for the wind turbine pitch bearing and hub pitch stud. Background Technology
[0002] In the pitch control system of wind turbines, the pitch bearing and the pitch stud on the hub are core load-bearing components that must withstand complex loads such as alternating bending moments of the blades and gust impacts over long periods. The reliability of their connection is directly related to the safety of the unit. However, existing technologies have significant drawbacks. For example, bolts are prone to loosening and failure. This is because most current installations use ordinary nuts and ordinary torque / tension, resulting in bolt preload errors often exceeding ±20%, and the annual preload loss rate under alternating loads is over 5%. Bolt loosening occurs after 3-5 years of operation. In some units, bolt loosening has led to pitch bearing wear, abnormal blade vibration, and even major accidents such as blade shedding. Moreover, each unit requires bolt maintenance once a year, with each maintenance requiring several hours of downtime, resulting in a significant direct loss of power generation. Furthermore, maintenance requires specialized high-altitude work equipment, leading to high maintenance costs per unit. The annual maintenance cost accounts for a significant portion of the wind farm's operating costs, becoming a prominent pain point in the cost control of wind turbines throughout their entire life cycle.
[0003] In summary, how to solve the problems of easy loosening and failure of pitch studs in pitch bearings and hubs, high maintenance risks and low maintenance efficiency are problems that urgently need to be solved by those skilled in the art. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a maintenance-free structure for the pitch bearing and hub pitch stud of a wind turbine, which can solve the problems of easy loosening and failure of the pitch stud of the pitch bearing and hub, high bolt maintenance risk and low maintenance efficiency.
[0005] Another objective of this invention is to provide an installation method for the maintenance-free structure of the pitch bearing and hub pitch stud of the aforementioned wind turbine.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A maintenance-free structure for a wind turbine pitch bearing and hub pitch stud includes:
[0008] A pitch stud is used to pass through the pitch bearing. The pitch stud is screwed into the blind hole thread of the hub, and the other end of the pitch stud is exposed on the upper surface of the pitch bearing.
[0009] A tapered main nut is screwed onto the pitch stud at one end near the pitch bearing;
[0010] A tapered sleeve is fitted onto the outer periphery of the pitch stud, and the tapered sleeve is located above the main nut with a tapered surface. The main nut with a tapered surface has a tapered contact surface at one end facing the tapered sleeve, and the inner tapered surface of the tapered sleeve matches the tapered contact surface.
[0011] A bearing-side rain guard ring is provided on the outer ring of the pitch bearing;
[0012] A clamping bracket is provided at its bottom on the rain guard ring on the bearing side, and the top of the clamping bracket is located above the tapered sleeve. The clamping bracket is used to simultaneously fix at least 6 of the pitch studs.
[0013] A clamping nut is screwed onto the outermost end of the pitch stud and presses the clamping bracket and the tapered sleeve onto the tapered main nut, so that the inner tapered surface and the tapered contact surface are tightly fitted to generate a radial clamping force.
[0014] In one embodiment, the angle between the side of the tapered contact surface and its central axis is 25°-30°.
[0015] In one embodiment, the ratio of the clamping length L of the pitch stud at the connection between the pitch bearing and the hub to the diameter d of the pitch stud, L / d, is greater than or equal to 10:1.
[0016] In one embodiment, the clamping bracket includes an arc-shaped top plate, a 7-shaped plate, and a bottom plate. The top of the 7-shaped plate is connected to the middle of the arc-shaped top plate, the bottom of the 7-shaped plate is connected to the bottom plate, and the bottom plate is connected to the bearing-side rain guard ring. The arc-shaped top plate is provided with at least 6 spaced through holes for the pitch stud to pass through.
[0017] In one embodiment, a blade root side rain guard ring disposed at the root of the blade is further included, wherein the blade root side rain guard ring and the bearing side rain guard ring together form a sealed cavity.
[0018] In one embodiment, both the bearing-side rain guard and the blade root-side rain guard are segmented structures, and the segments are sealed together, as are the bearing-side rain guard and the pitch bearing, and the blade root-side rain guard and the blade.
[0019] In one embodiment, the pitch stud is made of alloy structural steel, the pitch stud has a yield strength greater than or equal to 940 MPa, and the pitch stud has a tensile strength greater than or equal to 1080 MPa.
[0020] An installation method, applied to the maintenance-free structure of the wind turbine pitch bearing and hub pitch stud as described in any of the above claims, includes:
[0021] The robot applies anti-seize agent to the pitch stud, applies grease to the conical contact surface of the main nut with a conical surface and the inner conical surface of the conical sleeve, imports the three-dimensional model of the pitch bearing and hub into the robot's control system, performs benchmark calibration on the workpiece and establishes a real-time coordinate system through a laser positioning instrument, and presets the working parameters of the torque wrench and hydraulic tensioner at the end of the robot according to the diameter, length and preload parameters of the pitch stud in order to complete the tool calibration and force feedback system debugging.
[0022] The robot grasps the pitch stud, passes it through the pitch bearing, and screws it into the blind thread of the hub, thus installing the pitch stud into place.
[0023] The robot applies a preload to the tapered main nut using either the torque-rotation method or the hydraulic tension method, and controls the error between the preload and the preset force to be less than or equal to ±5%.
[0024] The robot sequentially installs the cone sleeve, clamping bracket, and clamping nut onto the pitch stud, and then tightens the clamping nut.
[0025] In one embodiment, the robot applies a preload to the tapered main nut using either a torque-rotation method or a hydraulic tensioning method, including:
[0026] When the robot selects the torque-angle method to apply preload to the tapered main nut, the robot first applies an initial torque of 30% of the target preload, and the torque value is fed back in real time through the torque sensor. After the torque reaches the target, the robot performs angle control according to the preset angle, and controls the accuracy of the angle to be less than or equal to ±1°. The data of the torque and the angle are recorded synchronously throughout the process.
[0027] When the robot selects the hydraulic tensioning method to apply preload to the tapered main nut, the robot automatically connects the hydraulic tensioner to the pitch stud. Through the coordinated control of pressure sensor and laser displacement sensor, the robot ensures that the elongation of the pitch stud reaches the design value and controls the error of the elongation to be less than or equal to ±0.02mm. While maintaining the tension of the hydraulic tensioner for a preset time, the robot monitors the pressure stability in real time. After the pressure stabilizes, the robot automatically tightens the tapered main nut.
[0028] In one embodiment, installing the pitch stud into place includes:
[0029] After the pitch stud is installed in place, the distance sensor on the robot automatically detects the thread length of the pitch bearing exposed at both ends of the pitch stud, ensuring that the difference in the exposed thread length at both ends is less than or equal to 0.5mm. If the difference in thread length is greater than 0.5mm, the robot automatically adjusts the position of the pitch stud until the difference in thread length is less than or equal to 0.5mm.
[0030] When using the maintenance-free structure for wind turbine pitch bearings and hub pitch studs provided by this invention, firstly, the robot applies an anti-seize agent to the pitch stud and applies grease to the conical contact surface of the main nut with a tapered surface and the inner conical surface of the tapered sleeve. Then, the three-dimensional models of the pitch bearing and hub are imported into the robot's control system. A laser positioning device is used to perform benchmark calibration and establish a real-time coordinate system. Based on the diameter, length, and preload parameters of the pitch stud, the working parameters of the torque wrench and hydraulic tensioner at the robot's end effector are preset to complete tool calibration and force feedback system debugging. Next, the robot grips the pitch stud, passes it through the pitch bearing, and screws it into the blind hole thread of the hub, ensuring the pitch stud is in place. Then, the robot applies a preload to the main nut with a tapered surface using either the torque-angle method or the hydraulic tensioning method, controlling the error between the preload and the preset force to be less than or equal to ±5%. Finally, the robot sequentially installs the tapered sleeve, clamping bracket, and clamping nut onto the pitch stud and tightens the clamping nut.
[0031] In this process, after the robot tightens the tapered main nut, a tapered sleeve and a clamping bracket are sequentially fitted onto the exposed threaded portion of the pitch stud, and then the clamping nut is tightened. Because the inner tapered surface of the tapered sleeve perfectly matches the tapered contact surface of the tapered main nut, under the axial tightening force of the clamping nut, the inner tapered surface of the tapered sleeve and the tapered contact surface of the tapered main nut gradually come into close contact. The axial tightening force is converted into radial preload, causing the tapered sleeve to tightly grip the tapered contact surface of the tapered main nut. This forces the tapered contact surface on the tapered main nut to undergo elastic deformation in the inner diameter direction, thereby gripping the pitch stud and enhancing the normal pressure and friction between the threads. This friction, combined with the friction of the threaded pair itself, forms a double anti-loosening guarantee, effectively resisting vibration and impact under alternating loads and preventing the tapered main nut from loosening.
[0032] Moreover, compared to traditional flat washer anti-loosening structures, this conical composite structure (i.e., a combination structure with a conical main nut, conical sleeve, and pitch stud) can increase the anti-loosening torque by 3-5 times, ensuring no loosening occurs within a 25-year operating cycle. Furthermore, the clamping bracket can simultaneously secure multiple pitch studs, preventing loosening due to individual studs breaking during field operation caused by factory quality issues, effectively reducing the frequency of bolt maintenance and avoiding losses caused by maintenance.
[0033] In summary, the maintenance-free structure for wind turbine pitch bearings and hub pitch studs provided by this invention can solve the problems of easy loosening and failure of pitch studs in pitch bearings and hubs, high bolt maintenance risks, and low maintenance efficiency.
[0034] In addition, the present invention also provides an installation method for the maintenance-free structure of the above-mentioned wind turbine pitch bearing and hub pitch stud. Attached Figure Description
[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0036] Figure 1 This is a partial schematic diagram of the maintenance-free structure of the wind turbine pitch bearing and hub pitch stud provided by the present invention.
[0037] Figure 2 This is a schematic diagram of the clamping bracket.
[0038] Figure 3 A front perspective view of the pitch stud, pitch bearing, and hub assembly.
[0039] Figure 4 This is a structural schematic diagram of the main perspective view of the blade root side rain guard ring, pitch stud, pitch bearing, and hub assembly.
[0040] Figure 5 A schematic diagram of the hub and pitch bearing;
[0041] Figure 6 This is a flowchart illustrating the installation method provided by the present invention.
[0042] Figures 1-6 middle:
[0043] 1. Blade, 2. Blade root side rain guard ring, 3. Conical sleeve, 4. Main nut with conical surface, 5. Pitch stud, 6. Compression nut, 7. Compression bracket, 8. Pitch bearing, 9. Bearing side rain guard ring, 10. Hub. Detailed Implementation
[0044] 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. 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.
[0045] The core of this invention is to provide a maintenance-free structure for the pitch bearing and hub pitch stud of a wind turbine, which solves the problems of easy loosening and failure of the pitch stud in the pitch bearing and hub, high bolt maintenance risk, and low maintenance efficiency. Another core aspect of this invention is to provide an installation method for the aforementioned maintenance-free structure for the pitch bearing and hub pitch stud of the wind turbine.
[0046] Please refer to Figure 1 and Figure 2 This specific embodiment provides a maintenance-free structure for a wind turbine pitch bearing and hub pitch stud, including:
[0047] The pitch stud 5 is used to pass through the pitch bearing 8. The pitch stud 5 is screwed into the blind hole thread of the hub 10, and the other end of the pitch stud 5 is exposed on the upper surface of the pitch bearing 8.
[0048] The main nut 4 with a tapered surface is screwed onto the end of the pitch stud 5 near the pitch bearing 8.
[0049] The tapered sleeve 3 is sleeved on the outer periphery of the pitch stud 5 and is located above the tapered main nut 4. The tapered main nut 4 has a tapered contact surface at one end facing the tapered sleeve 3, and the inner tapered surface of the tapered sleeve 3 matches the tapered contact surface.
[0050] The bearing-side rain guard ring 9 is located on the outer ring of the pitch bearing 8;
[0051] The clamping bracket 7 has its bottom located on the rain guard ring 9 on the bearing side, and its top is located above the tapered sleeve 3. The clamping bracket 7 is used to simultaneously fix at least 6 pitch studs 5.
[0052] The clamping nut 6 is screwed onto the outermost end of the pitch stud 5 and presses the clamping bracket 7 and the cone sleeve 3 onto the main nut 4 with a conical surface, so that the inner cone surface and the conical contact surface are tightly fitted to generate radial clamping force.
[0053] It should be noted that the three pitch bearings 8 are connected and fixed to the three blade root mounting surfaces of the hub 10 via pitch studs 5. The pitch studs 5 pass vertically through the pitch bearings 8, with one end screwed into the blind hole thread of the hub 10, and the threaded portion of the other end exposed on the surface of the pitch bearing 8. During assembly, firstly, the tapered main nut 4 is pre-tightened using a tensioning method. Then, a tapered sleeve 3 is installed on the upper side of the tapered main nut 4. A clamping bracket 7 is then installed sequentially on the upper side of the tapered sleeve 3. Finally, the clamping nut 6 is screwed in to complete the anti-loosening assembly. Figure 2 As shown, a clamping bracket 7 is fixed under the clamping nut 6 of every 6 pitch studs 5. The clamping bracket 7 can prevent individual pitch studs 5 from breaking and coming loose during field operation due to factory quality problems, and can also be used to fix the rain guard ring 9 on the bearing side.
[0054] In practical applications, the shape, structure, and type of the pitch stud 5, the main nut with tapered surface 4, the tapered sleeve 3, the bearing side rain guard 9, the clamping bracket 7, and the clamping nut 6 can be determined according to the actual situation and needs.
[0055] When using the maintenance-free structure for the wind turbine pitch bearing and hub pitch stud provided by this invention, firstly, the robot applies an anti-seize agent to the pitch stud 5, and applies grease to the conical contact surface of the tapered main nut 4 and the inner conical surface of the tapered sleeve 3. Then, the three-dimensional models of the pitch bearing 8 and hub 10 are imported into the robot's control system. A laser positioning device is used to perform benchmark calibration and establish a real-time coordinate system. Based on the diameter, length, and preload parameters of the pitch stud 5, the working parameters of the torque wrench and hydraulic tensioner at the robot's end effector are preset to complete tool calibration and force feedback system debugging. Next, the robot grips the pitch stud 5, passes it through the pitch bearing 8, and screws it into the blind hole thread of the hub 10, ensuring the pitch stud 5 is in place. Then, the robot selects either the torque-angle method or the hydraulic tensioning method to apply a preload to the tapered main nut 4, controlling the error between the preload and the preset force to be less than or equal to ±5%. Finally, the robot sequentially installs the cone sleeve 3, clamping bracket 7, and clamping nut 6 onto the pitch stud 5, and tightens the clamping nut 6.
[0056] In this process, after the robot tightens the tapered main nut 4, the tapered sleeve 3 and the clamping bracket 7 are sequentially fitted onto the exposed threaded portion of the pitch stud 5, and then the clamping nut 6 is tightened. Because the inner tapered surface of the tapered sleeve 3 perfectly matches the tapered contact surface of the tapered main nut 4, under the axial tightening force of the clamping nut 6, the inner tapered surface of the tapered sleeve 3 and the tapered contact surface of the tapered main nut 4 gradually become tightly fitted together. The axial tightening force is converted into a radial preload, causing the tapered sleeve 3 to tightly grip the tapered contact surface of the tapered main nut 4. This forces the tapered contact surface on the tapered main nut 4 to undergo elastic deformation in the inner diameter direction, thereby gripping the pitch stud 5 and enhancing the normal pressure and friction between the threads. This friction, together with the friction of the threaded pair itself, forms a double anti-loosening guarantee, effectively resisting vibration and impact under alternating loads and preventing the tapered main nut 4 from loosening.
[0057] Moreover, compared to traditional flat washer anti-loosening structures, this conical composite structure (i.e., a combination structure with a conical main nut 4, a conical sleeve 3, and a pitch stud 5) can increase the anti-loosening torque by 3-5 times, ensuring no loosening during a 25-year operating cycle. Furthermore, the clamping bracket 7 can simultaneously secure multiple pitch studs 5, preventing loosening due to individual pitch studs 5 breaking during field operation caused by factory quality issues, effectively reducing the frequency of bolt maintenance and avoiding losses caused by maintenance.
[0058] In summary, the maintenance-free structure for wind turbine pitch bearings and hub pitch studs provided by this invention can solve the problems of easy loosening and failure of pitch studs in pitch bearings and hubs, high bolt maintenance risks, and low maintenance efficiency.
[0059] In one embodiment, the angle between the side of the tapered contact surface and its central axis is 25°-30°.
[0060] It should be noted that the tapered main nut 4 is assembled on the end of the pitch stud 5 near the pitch bearing 8. The end of the tapered main nut 4 facing the tapered sleeve 3 has a tapered contact surface, and the angle of the tapered contact surface is designed to be 25°-30° (preferably 28°; if the angle of the tapered main nut 4 is too large, it may not produce a sufficient squeezing effect) to ensure a tight fit between the tapered main nut 4 and the tapered sleeve 3. The tapered main nut 4 can be made of 35CrMo steel, carburized and quenched to a hardness of HRC38-42, possessing good wear resistance and deformation resistance.
[0061] In one embodiment, the ratio of the clamping length L of the pitch stud 5 at the connection between the pitch bearing 8 and the hub 10 to the diameter d of the pitch stud 5, L / d, is greater than or equal to 10:1. This ensures that the assembly preload loss under operating conditions can be controlled within 5% without the tapered main nut 4 becoming loose, thus ensuring that the pitch stud 5 and the tapered main nut 4 always remain effectively clamped.
[0062] In one embodiment, the clamping bracket 7 includes an arc-shaped top plate, a 7-shaped plate, and a bottom plate. The top of the 7-shaped plate is connected to the middle of the arc-shaped top plate, the bottom of the 7-shaped plate is connected to the bottom plate, and the bottom plate is connected to the bearing-side rain guard ring 9. The arc-shaped top plate has at least six spaced-apart through holes for the pitch stud 5 to pass through. Moreover, the arc-shaped top plate, the 7-shaped plate, and the bottom plate are an integral structure.
[0063] In one embodiment, a blade root side rainproof ring 2 is provided at the root of the blade 1, and the blade root side rainproof ring 2 and the bearing side rainproof ring 9 together form a sealed cavity.
[0064] In one embodiment, both the bearing-side rain guard 9 and the blade root-side rain guard 2 are segmented structures, and the segments are sealed together, as are the bearing-side rain guard 9 and the pitch bearing 8, and the blade root-side rain guard 2 and the blade 1.
[0065] It should be noted that the blade root side rain guard 2 adopts a segmented structure. Each segment is fixed to the root of the blade 1 with screws, and the segments are also connected and fixed with screws. All flange gaps at the screw connections are coated with sealant to ensure a tight seal. Similarly, the bearing side rain guard 9 also adopts a segmented structure. Each segment is fixed to the outer ring of the pitch bearing 8 with screws, and the segments are also connected and fixed with screws. The flange gaps at the screw connections are also coated with sealant. Furthermore, after the blade 1 is hoisted on-site, the blade root side rain guard 2 and the bearing side rain guard 9 together form a cavity with a labyrinth seal and a brush seal to achieve a rain and dustproof seal, effectively preventing external rainwater from entering and preventing corrosion of core components such as the pitch stud 5 and the tapered main nut 4, thus ensuring the reliability of the connection structure.
[0066] Because this structure achieves 25 years of maintenance-free operation through its anti-loosening design and requires no space for future maintenance, the traditional turbine fairing structure can be eliminated, and replaced by the blade root side rain guard 2 and the bearing side rain guard 9. Furthermore, when it is necessary to check the operating status of the pitch stud 5, operators can directly remove the blade root side rain guard 2 for visual inspection without disassembling other core components.
[0067] In other words, this application achieves full-cycle maintenance-free operation of the connection structure through a 25-year maintenance-free bolt design and corrosion-resistant sealing protection of the blade root-side rain guard ring 2 and the bearing-side rain guard ring 9. No space needs to be reserved for future bolt maintenance. Therefore, this application eliminates the traditional turbine fairing design, with the protective function of the fairing completely replaced by a sealed cavity formed by the rain guard rings. This design is one of the core innovations of this application. On the one hand, the absence of a fairing directly reduces the manufacturing cost of this component and simplifies the overall assembly process of the turbine. On the other hand, eliminating the fairing significantly reduces the overall size of the pitch system, effectively reducing packaging, loading, and transportation costs during logistics and transportation, while also reducing transportation volume and improving transportation efficiency. It is suitable for the transportation and installation needs of various power levels of wind turbines onshore and offshore, balancing protection, economy, and transportation convenience.
[0068] In one embodiment, the pitch stud 5 is made of alloy structural steel, and the pitch stud 5 has a yield strength greater than or equal to 940 MPa and a tensile strength greater than or equal to 1080 MPa.
[0069] It should be noted that the pitch stud 5, as the core load-bearing component of the entire connection structure, needs to penetrate the corresponding connection holes of the pitch bearing 8 and the hub 10 to achieve a rigid connection between the two. The pitch stud 5 is made of high-strength alloy structural steel (grade 42CrMoA, heat-treated), with a yield strength greater than or equal to 940MPa and a tensile strength greater than or equal to 1080MPa, which can stably withstand complex loads such as alternating bending moment and centrifugal force transmitted by the blade 1. Furthermore, the tapered sleeve 3 is an annular sleeve structure, assembled on the exposed threaded part of the pitch stud 5. The inner tapered surface of the tapered sleeve 3 is perfectly matched with the tapered contact surface of the main nut 4 with a tapered surface. The tapered sleeve 3 can be manufactured using the same material as the pitch stud 5.
[0070] It should also be noted that, through the coordinated design of the conical combined anti-loosening structure (i.e., the conical sleeve 3 and the conical main nut 4), the pitch stud 5, and high-precision preload control, the preload loss of the pitch stud 5 is less than or equal to 5% over a 25-year operating cycle, and the anti-loosening torque is 3-5 times higher than that of traditional structures. This completely solves the problem of easy bolt loosening and failure in existing technologies, effectively avoiding safety accidents such as uneven wear of pitch bearings, blade vibration, and even blade detachment, significantly improving the operational safety of the unit. Moreover, the conical combined anti-loosening structure of this application requires no subsequent maintenance, eliminates the need for the large-size fairing of traditional units, avoids maintenance work in confined spaces at high altitudes, completely eliminates the safety risks for maintenance personnel, and saves the annual bolt maintenance work. A single unit can reduce downtime maintenance time by 4-6 hours per year and increase power generation by approximately 20,000-30,000 kWh (calculated based on a single unit capacity of 5MW).
[0071] Furthermore, eliminating the fairing design can reduce the manufacturing cost of a single unit by tens of thousands of yuan, reduce the risk of damage during transportation, and eliminate annual maintenance costs such as equipment rental, labor, and downtime losses, thus reducing the average annual maintenance cost per unit and significantly improving the return on investment for wind farms. In addition, the integrated assembly structure of this application does not require changes to the core design of the existing pitch bearing 8 and hub 10. Upgrades can be achieved simply by optimizing the combination of bolt assemblies (such as the longer pitch stud 5), anti-loosening components (such as the main nut 4 with a tapered surface and the tapered sleeve 3), and protective components (such as the bearing side rain guard 9 and the blade root side rain guard 2). It is applicable to wind turbines of various power levels both onshore and offshore, and has strong compatibility.
[0072] In addition to the aforementioned maintenance-free structure for wind turbine pitch bearings and hub pitch studs, this invention also provides an installation method for the maintenance-free structure for wind turbine pitch bearings and hub pitch studs disclosed in the above embodiments. This installation method includes:
[0073] S1. The robot applies anti-seize agent to the pitch stud 5, applies grease to the conical contact surface of the main nut 4 with conical surface and the inner conical surface of the conical sleeve 3, imports the three-dimensional model of the pitch bearing 8 and the hub 10 into the robot's control system, performs benchmark calibration on the workpiece and establishes a real-time coordinate system through the laser positioning instrument, and presets the working parameters of the torque wrench and hydraulic tensioner at the end of the robot according to the diameter, length and preload parameters of the pitch stud 5, so as to complete the tool calibration and force feedback system debugging.
[0074] S2. The robot grasps the pitch stud 5, passes through the pitch bearing 8, and screws it into the blind hole thread of the hub 10, thus installing the pitch stud 5 into place.
[0075] S3. The robot selects either the torque-rotation method or the hydraulic tension method to apply preload to the tapered main nut 4, and controls the error between the preload and the preset force to be less than or equal to ±5%.
[0076] S4. The robot sequentially installs the cone sleeve 3, clamping bracket 7, and clamping nut 6 onto the pitch stud 5, and tightens the clamping nut 6.
[0077] In one embodiment, the robot applies a preload to the tapered main nut 4 using either a torque-rotation method or a hydraulic tensioning method, including:
[0078] When the robot selects the torque-angle method to apply preload to the tapered main nut 4, the robot first applies an initial torque of 30% of the target preload, and the torque value is fed back in real time through the torque sensor. After the torque reaches the target, the robot performs angle control according to the preset angle, and controls the angle accuracy to be less than or equal to ±1°. The torque and angle data are recorded synchronously throughout the process.
[0079] When the robot selects the hydraulic tensioning method to apply preload to the tapered main nut 4, the robot automatically connects the hydraulic tensioner and the pitch stud 5. Through the coordinated control of the pressure sensor and the laser displacement sensor, the robot ensures that the elongation of the pitch stud 5 reaches the design value and controls the elongation error to be less than or equal to ±0.02mm. While maintaining the tension of the hydraulic tensioner for a preset time, the robot monitors the pressure stability in real time. After the pressure stabilizes, the robot automatically tightens the tapered main nut 4.
[0080] In one embodiment, installing the pitch stud 5 into place includes:
[0081] After the pitch stud 5 is installed in place, the distance sensor on the robot automatically detects the thread length of the pitch bearing 8 exposed at both ends of the pitch stud 5, ensuring that the difference in the thread length at both ends is less than or equal to 0.5mm. If the difference in thread length is greater than 0.5mm, the robot automatically adjusts the position of the pitch stud 5 until the difference in thread length is less than or equal to 0.5mm.
[0082] To further illustrate the installation method provided by this invention, an example is given below. The installation method of this application is based on an intelligent robot system to achieve fully automated assembly and monitoring. Through the robot's high-precision positioning, torque closed-loop control, and real-time data feedback functions, installation accuracy and consistency are ensured, while reducing the risk of human intervention. Specifically, it includes the following steps:
[0083] Step 1: Parts Preprocessing and Robot Initialization
[0084] The pitch stud 5, the tapered main nut 4, and the tapered sleeve 3 are uniformly surface-treated by an automated pre-treatment workstation. Specifically, the threaded surface of the pitch stud 5 is automatically coated with a quantitative anti-seize agent by the robot's end effector, with the coating thickness controlled between 0.1-0.2 mm to ensure complete coverage of the threads. The inner tapered surface of the tapered sleeve 3 and the tapered contact surface of the tapered main nut 4 are uniformly coated with grease by a high-precision spraying module mounted on the robot. The coating range is precisely matched to the tapered contact area to avoid waste and contamination.
[0085] Then, the three-dimensional models of the pitch bearing 8 and hub 10 are imported into the robot's control system. The workpiece is calibrated by the laser positioning instrument, and a real-time coordinate system is established. Based on the bolt specifications (diameter, length) and preload parameters, the working parameters of the robot's end torque wrench and hydraulic tensioner are preset to complete the tool calibration and force feedback system debugging.
[0086] Step 2: Automated installation of pitch stud 5
[0087] The robot uses a visual recognition system to grasp the pitch stud 5. Based on a preset coordinate system and real-time visual positioning, it accurately passes the pitch stud 5 through the corresponding connection hole between the pitch bearing 8 and the hub 10. The entire process uses a force control mode to avoid collision and wear between the pitch stud 5 and the hole wall.
[0088] After the pitch stud 5 is installed in place, the distance sensor on the robot automatically detects the exposed thread length at both ends of the pitch stud 5, ensuring that the length difference between the two ends of the pitch stud 5 is less than or equal to 0.5mm. If the length difference exceeds the threshold, the position of the pitch stud 5 is automatically adjusted until the assembly requirements are met, and the data is uploaded to the background database in real time for storage.
[0089] Step 3: Intelligent preload with tapered main nut 4
[0090] The robot switches to a pre-tightening tool (torque-angle integrated wrench or hydraulic tensioner) and selects the corresponding pre-tightening method according to the preset process:
[0091] If the torque-angle method is used, the robot first applies an initial torque of 30% of the target torque, and the torque value is fed back in real time through the torque sensor. After the target is met, the angle is controlled according to the preset angle. The angle accuracy is less than or equal to ±1°, and the torque and angle data are recorded synchronously throughout the process.
[0092] If the hydraulic stretching method is used, the robot automatically docks the hydraulic stretcher with the pitch stud 5. Through the coordinated control of the pressure sensor and the laser displacement sensor, the elongation of the pitch stud 5 reaches the design value, and the elongation error is less than or equal to ±0.02mm. During the period of maintaining the tension of the hydraulic stretcher for 30 seconds, the robot monitors the pressure stability of the hydraulic stretcher in real time. After the pressure is stable, the robot automatically tightens the tapered main nut 4.
[0093] Both pre-tightening methods use a robot closed-loop control system to ensure that the pre-tightening force error is less than or equal to ±5%.
[0094] Step 4: Automated assembly of anti-loosening components
[0095] The robot sequentially picks up the cone sleeve 3, the clamping bracket 7, and the clamping nut 6, and precisely inserts them into the exposed threaded part of the pitch stud 5 according to the assembly sequence. The tightening torque of the clamping nut 6 is adaptively adjusted according to 40-50% of the pre-tightening torque of the main body.
[0096] Step 5: Manual installation of protective components
[0097] Fix the segments of the bearing-side rain guard ring 9 onto the clamping bracket 7, apply sealant and press it firmly to ensure that the sealant evenly covers the contact surface. Then fix the blade root-side rain guard ring 2 at the root of the blade 1 and adjust the position so that the labyrinth seal gap meets the requirements, and the brush is in close contact with the surface of the bearing-side rain guard ring 9 without excessive compression.
[0098] In addition, it should be noted that the orientation or positional relationship indicated by "top and bottom", "inner and outer", etc. in this application is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the purpose of simplifying the description and making it easier to understand, and is not intended to 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 the present invention.
[0099] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Any combination of all embodiments provided by this invention is within the scope of protection of this invention and will not be elaborated upon here.
[0100] The foregoing has provided a detailed description of the maintenance-free structure and installation method for the wind turbine pitch bearing and hub pitch stud provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.
Claims
1. A maintenance-free structure for a wind turbine pitch bearing and hub pitch stud, characterized in that, include: A pitch stud (5) is used to pass through the pitch bearing (8). The pitch stud (5) is screwed into the blind hole thread of the hub (10). The other end of the pitch stud (5) is exposed on the upper surface of the pitch bearing (8). A tapered main nut (4) is screwed onto one end of the pitch stud (5) near the pitch bearing (8); A tapered sleeve (3) is fitted around the outer periphery of the pitch stud (5), and the tapered sleeve (3) is located above the main nut (4) with a tapered surface. The main nut (4) with a tapered surface has a tapered contact surface at one end facing the tapered sleeve (3), and the inner tapered surface of the tapered sleeve (3) matches the tapered contact surface. A bearing-side rain guard ring (9) is provided on the outer ring of the pitch bearing (8); The clamping bracket (7) is located at the bottom of the bearing side rain guard ring (9), and the top of the clamping bracket (7) is located above the tapered sleeve (3). The clamping bracket (7) is used to fix at least 6 of the pitch studs (5) at the same time. The clamping nut (6) is screwed onto the outermost end of the pitch stud (5) and presses the clamping bracket (7) and the cone sleeve (3) onto the main nut (4) with a conical surface, so that the inner cone surface and the conical contact surface are closely fitted to generate a radial clamping force.
2. The maintenance-free structure for the wind turbine pitch bearing and hub pitch stud according to claim 1, characterized in that, The angle between the side of the conical contact surface and its central axis is 25°-30°.
3. The maintenance-free structure for the wind turbine pitch bearing and hub pitch stud according to claim 1, characterized in that, The ratio of the clamping length L of the pitch stud (5) at the connection between the pitch bearing (8) and the hub (10) to the diameter d of the pitch stud (5) is greater than or equal to 10:
1.
4. The maintenance-free structure for wind turbine pitch bearing and hub pitch stud according to any one of claims 1 to 3, characterized in that, The clamping bracket (7) includes an arc-shaped top plate, a 7-shaped plate and a bottom plate. The top of the 7-shaped plate is connected to the middle of the arc-shaped top plate, the bottom of the 7-shaped plate is connected to the bottom plate, and the bottom plate is connected to the bearing side rain guard ring (9). The arc-shaped top plate is provided with at least 6 spaced through holes for the pitch stud (5) to pass through.
5. The maintenance-free structure for wind turbine pitch bearing and hub pitch stud according to any one of claims 1 to 3, characterized in that, It also includes a blade root side rain guard (2) located at the root of the blade (1), and the blade root side rain guard (2) and the bearing side rain guard (9) together form a sealed cavity.
6. The maintenance-free structure for the wind turbine pitch bearing and hub pitch stud according to claim 5, characterized in that, The bearing-side rain guard (9) and the blade root-side rain guard (2) are both segmented structures, and the segments are sealed together, as are the bearing-side rain guard (9) and the pitch bearing (8), and the blade root-side rain guard (2) and the blade (1).
7. The maintenance-free structure for wind turbine pitch bearing and hub pitch stud according to any one of claims 1 to 3, characterized in that, The pitch stud (5) is made of alloy structural steel. The yield strength of the pitch stud (5) is greater than or equal to 940 MPa, and the tensile strength of the pitch stud (5) is greater than or equal to 1080 MPa.
8. An installation method applied to the maintenance-free structure of the wind turbine pitch bearing and hub pitch stud as described in any one of claims 1 to 7, characterized in that, include: The robot applies anti-seize agent to the pitch stud (5), applies grease to the conical contact surface of the main nut (4) with conical surface and the inner conical surface of the conical sleeve (3), imports the three-dimensional model of the pitch bearing (8) and the hub (10) into the robot's control system, performs benchmark calibration on the workpiece and establishes a real-time coordinate system through the laser positioning instrument, and presets the working parameters of the torque wrench and hydraulic tensioner at the end of the robot according to the diameter, length and preload parameters of the pitch stud (5) to complete the tool calibration and force feedback system debugging; The robot grasps the pitch stud (5), passes it through the pitch bearing (8), and screws it into the blind hole thread of the hub (10), thus installing the pitch stud (5) into place. The robot selects either the torque-rotation method or the hydraulic tension method to apply a preload to the tapered main nut (4), and controls the error between the preload and the preset force to be less than or equal to ±5%. The robot sequentially installs the cone sleeve (3), clamping bracket (7), and clamping nut (6) onto the pitch stud (5) and tightens the clamping nut (6).
9. The installation method according to claim 8, characterized in that, The robot applies a preload to the tapered main nut (4) using either the torque-rotation method or the hydraulic tension method, including: When the robot selects the torque-angle method to apply preload to the tapered main nut (4), the robot first applies an initial torque of 30% of the target preload, and the torque value is fed back in real time through the torque sensor. After the torque reaches the target, the robot performs angle control according to the preset angle, and controls the accuracy of the angle to be less than or equal to ±1°. The data of the torque and the angle are recorded synchronously throughout the process. When the robot selects the hydraulic tensioning method to apply preload to the tapered main nut (4), the robot automatically connects the hydraulic tensioner to the pitch stud (5), and through the coordinated control of the pressure sensor and the laser displacement sensor, the elongation of the pitch stud (5) reaches the design value, and the error of the elongation is controlled to be less than or equal to ±0.02mm. During the preset time of maintaining the tension of the hydraulic tensioner, the robot monitors the pressure stability in real time, and automatically tightens the tapered main nut (4) after the pressure has no fluctuation.
10. The installation method according to claim 8, characterized in that, The process of installing the pitch stud (5) into place includes: After the pitch stud (5) is installed in place, the distance sensor on the robot automatically detects the thread length of the pitch bearing (8) exposed at both ends of the pitch stud (5), ensuring that the difference in the thread length exposed at both ends is less than or equal to 0.5mm. If the difference in the thread length is greater than 0.5mm, the robot automatically adjusts the position of the pitch stud (5) until the difference in the thread length is less than or equal to 0.5mm.