Blade root embedded part and fan blade root connecting structure

Abstract

The present application relates to a kind of blade root embedded parts, the embedded part is cylindrical structure, the bottom inner cylinder wall of the embedded part is equipped with several rows of through holes for being connected with shear bolt.Compared with prior art, the embedded part of the present application is cylindrical structure, the bottom inner cylinder wall of the embedded part is equipped with several rows of through holes for being connected with shear bolt, the embedded part is used, and the blade root connection design of tensile form is changed to shear form.Because the pre-tightening force of shear bolt generates pressure between blade root and variable pitch bearing, the friction between the two is increased, and the friction can resist a part of blade bending moment in the shear force of blade root and variable pitch bearing inner ring joint surface, so as to improve the strength of blade root connection.

Description

Technical Field

[0001] This invention relates to the field of wind turbine technology, specifically to a blade root embedded part and a wind turbine blade root connection structure. Background Technology

[0002] A wind turbine is a device that converts wind energy into mechanical energy and then into electrical energy. It includes a tower and a nacelle connected to the tower and supporting a hub. Several wind turbine blades are arranged on the hub, and these blades, driven by wind, rotate a rotor located in the hub around its axis. The rotation of the rotor relative to the stator generates electrical energy. There are generally two methods for connecting the blade root to the pitch bearing: T-type perforated connection and pre-embedded root bolt sleeve connection. As blade length increases and wind turbine generators reach megawatt levels, blade loads also increase. More and more blades are transitioning from the traditional T-type perforated connection method to the pre-embedded root bolt sleeve connection method to accommodate more connecting bolts at the blade root, ensuring that the root connecting bolts have sufficient ultimate strength and fatigue strength.

[0003] Existing wind turbine blade root embedded structures are mostly tensile-type blade root connection structures, which have the following disadvantages:

[0004] (1) To facilitate grinding with a high-speed metal grinder, the blade root embedded bolt sleeves generally protrude from the end face of the blade root composite material. Due to the curing shrinkage of the composite material, after the blade is molded, the end face of the blade root embedded bolt sleeve at the mold joint is usually significantly lower than the end face of the bolt sleeve at other positions. Moreover, the larger the blade pitch circle, the greater the shrinkage at the mold joint. In order to ensure the flatness of the end face of the blade root embedded bolt sleeve, during end face grinding, the end face of the blade root embedded bolt sleeve near the mold joint is not ground, while the end face of the blade root embedded bolt sleeve at other positions has been ground to be flush with the blade root composite material. When the high-speed metal grinder touches the composite material, the high-speed friction generates heat, and the composite material is easily burned, resulting in a deterioration of its mechanical properties.

[0005] (2) The end face area of ​​the pre-embedded bolt sleeve at the leaf root is small. When it comes into contact with the flange end face, the stiffness of the connected parts is small, and the fatigue life of the connecting bolts is reduced.

[0006] (3) In the traditional blade root pre-embedded connection structure, only the bolt sleeve, flange and pitch bearing are the compressed components. The blade root composite material is not compressed and does not contribute to the stiffness of the connected parts, which reduces the maximum pull-out force of the pre-embedded bolt sleeve and the fatigue resistance of the connecting bolt.

[0007] The above three drawbacks make it difficult to control the manufacturing process of pre-embedded blades. At the same time, during the operation of the wind turbine, the fatigue life of the blade root bolts is short and the blade root bolts break frequently, which reduces the reliability and service life of the wind turbine blades. Summary of the Invention

[0008] The purpose of this invention is to overcome at least one of the defects in the prior art by providing a blade root embedded part and a wind turbine blade root connection structure. This embedded part changes the tensile-resistant blade root connection design to a shear-resistant one. Because the preload of the shear bolts generates pressure between the blade root and the pitch bearing, the friction between them increases. This friction resists a portion of the blade bending moment at the shear force on the mating surface between the blade root and the inner ring of the pitch bearing, thereby improving the strength of the blade root connection.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] One of the objectives of this invention is to provide a blade root embedded component, which is a cylindrical structure, wherein the inner wall of the bottom of the blade root embedded component is provided with several rows of through holes for connection with shear bolts.

[0011] Furthermore, the leaf root pre-embedded part has at least one row of through holes, preferably two rows of through holes, and the through holes in each row are evenly distributed along the circumference of the leaf root pre-embedded part.

[0012] Furthermore, the number of through holes on each row is equal.

[0013] Furthermore, the adjacent through holes between the different rows are set on the same generatrix of the leaf root embedded part.

[0014] Furthermore, the adjacent through holes between different rows are not located on the same generatrix of the leaf root embedded part.

[0015] Furthermore, both the inner and outer surfaces of the blade root embedded part are provided with threaded grooves or rotary grooves. The outer surface of the blade root embedded part is wound with fiber filaments, and the inner surface is bonded to the blade fiber material, thereby improving the bonding strength with the blade root fiber material.

[0016] Furthermore, the number of through holes in each row is greater than or equal to four.

[0017] Furthermore, the inner wall of the through hole is provided with threads that match the shear bolt.

[0018] The second objective of this invention is to provide a wind turbine blade root connection structure, comprising a blade root, a shear bolt, a pitch bearing, and a blade root embedded part as described above; the blade root embedded part is embedded to the bottom of the blade root, and the pitch bearing and the blade root are connected by a shear bolt that penetrates the blade root embedded part.

[0019] Furthermore, there are at least four blade root embedded parts, which are evenly distributed along the circumference of the blade root.

[0020] Compared with existing technologies, the blade root embedded part designed in this invention has a cylindrical structure. The inner wall of the bottom of the embedded part has several rows of through holes for connecting with shear bolts. Using this embedded part, the tensile blade root connection design is changed to a shear connection. Because the preload of the shear bolts generates pressure between the blade root and the pitch bearing, the friction between them is increased. This friction will resist part of the blade bending moment at the shear force on the mating surface between the blade root and the inner ring of the pitch bearing, thereby improving the strength of the blade root connection. Attached Figure Description

[0021] Figure 1 The images show the front view (a), top view (b), and cross-sectional view (c) of the leaf root embedded part in Example 1.

[0022] Figure 2 This is a front view of the leaf root embedded part in Example 2;

[0023] Figure 3 This is a schematic diagram of the fan blade root connection structure in Example 1;

[0024] The numbers in the diagram indicate: 101-blade root; 102-blade root embedded part; 1021-cylindrical structure; 1022-through hole; 103-shear bolt; 104-pitch bearing; 105-hull. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] Example 1

[0027] Figure 1 The images show the front view (a), top view (b), and cross-sectional view (c) of the leaf root embedded part in Example 1. Figure 1 As shown, a blade root embedded part 102 is a cylindrical structure 1021. The inner wall of the bottom of the blade root embedded part 102 is provided with several rows of through holes 1022 for connecting with shear bolts 103.

[0028] The blade root embedded part 102 has at least two rows of through holes 1022, with each row of through holes 1022 evenly distributed circumferentially around the blade root embedded part 102. The number of through holes 1022 in each row is equal. Adjacent through holes 1022 in different rows are located on the same generatrix of the blade root embedded part 102. Both the inner and outer surfaces of the blade root embedded part 102 are provided with threaded grooves or rotary grooves. Each row has at least four through holes 1022. The inner wall of the through holes 1022 is provided with threads that match the shear bolts 103.

[0029] Figure 3This is a schematic diagram of a wind turbine blade root connection structure. Figure 3 As shown, a wind turbine blade root connection structure includes a blade root 101, shear bolts 103, a pitch bearing 104, and blade root embedded parts 102. At least four blade root embedded parts 102 are provided in the blade root 101, evenly distributed along the circumference of the blade root 101, and embedded in the bottom of the blade root 101. More specifically, during the blade root manufacturing process, the inner surface of the blade root embedded part 102 is bonded to the blade fiber material, and the outer surface is wound with glass fiber yarn. The outer surface of the yarn is flush with the outer surface of the blade root embedded part 102 in a small enveloping cylinder. It is then placed into the blade root layup and integrally molded with the other glass fiber materials of the blade root by resin injection. During blade installation, the shear bolts 103 are screwed into the blade root embedded parts 102, so that the end face of the blade root 101 is tightly connected to the inner ring of the pitch bearing 104. The hub 105 and the pitch bearing 104 are connected by bolts.

[0030] Compared to existing blade root connection structures designed for tension, this invention designs the blade root bolts for shear stress. To enhance the blade root's strength, embedded parts are added to the blade root, distributed circumferentially. When the blade is under load, the blade bending moment causes the blade root to be under tension or compression on one side. The shear bolts will withstand and resist the shear force at the contact surface between the blade root and the pitch bearing, thus achieving the connection function between the blade root and the pitch bearing. Because the preload of the shear bolts generates pressure between the blade root and the pitch bearing, it increases the friction between them. This friction resists a portion of the shear force from the blade bending moment at the mating surface between the blade root and the inner ring of the pitch bearing, thereby improving the strength of the blade root connection.

[0031] Example 2

[0032] Figure 2 This is a front view of the leaf root embedded part in Example 2, as shown below. Figure 2 As shown, the structure of the leaf root embedded part described in Embodiment 2 is basically the same as that of the leaf root embedded part described in Embodiment 1. The difference is that the adjacent through holes 1022 between different rows on the leaf root embedded part 102 are not set on the same generatrix of the leaf root embedded part 102.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A fan blade root connection structure, characterized in that, It includes blade root (101), shear bolt (103), pitch bearing (104) and blade root embedded part (102). The blade root embedded part (102) is embedded to the bottom of the blade root (101), and the pitch bearing (104) and the blade root (101) are connected by shear bolts (103) that penetrate the blade root embedded part (102); The leaf root embedded part (102) is a cylindrical structure (1021), and the bottom inner wall of the leaf root embedded part (102) is provided with several rows of through holes (1022) for connecting with shear bolts (103). The embedded part changes the tensile type blade root connection design to a shear type. Since the preload of the shear bolt (103) generates pressure between the blade root (101) and the pitch bearing (104), the friction between the two increases. This friction will resist part of the blade bending moment at the shear force of the inner ring mating surface of the blade root (101) and the pitch bearing (104), thereby improving the strength of the blade root connection.

2. The fan blade root connection structure according to claim 1, characterized in that, The leaf root pre-embedded part (102) has at least one row of through holes (1022), and the through holes (1022) in each row are evenly distributed around the leaf root pre-embedded part (102).

3. The fan blade root connection structure according to claim 1, characterized in that, The number of through holes (1022) on each row is equal.

4. The fan blade root connection structure according to claim 2, characterized in that, The adjacent through holes (1022) between different rows are set on the same generatrix of the leaf root embedded part (102).

5. The fan blade root connection structure according to claim 2, characterized in that, The adjacent through holes (1022) between different rows are not set on the same generatrix of the leaf root embedded part (102).

6. The fan blade root connection structure according to claim 1, characterized in that, The inner and outer surfaces of the leaf root embedded part (102) are provided with threaded grooves or rotary grooves.

7. The fan blade root connection structure according to claim 1, characterized in that, The number of through holes (1022) in each row is greater than or equal to 4.

8. The fan blade root connection structure according to claim 1, characterized in that, The inner wall of the through hole (1022) is provided with threads that match the shear bolt (103).

9. A fan blade root connection structure according to claim 1, characterized in that, There are at least four leaf root embedded parts (102), and the leaf root embedded parts (102) are evenly distributed around the leaf root (101).

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