An embedded bolt connection structure for large wind turbine blades with an adapter flange

Abstract

The present invention relates to a pre-embedded bolt connection structure for a large wind turbine blade with an adapter flange. In this connection structure, the outer skin, inner skin, inner ring prefabricated component and outer ring prefabricated component are integrally pultruded by the RTM process, then the blade is connected to the adapter flange through high-strength bolts, and finally the adapter flange is connected to the pitch bearing of the hub by using high-strength bolts. Among them, the inner ring prefabricated component and the outer ring prefabricated component are arranged in a staggered manner. The splicing joints of the prefabricated embedded parts in the present invention are alternately distributed, and the sides of the prefabricated parts are grooved, so that the resin fluidity can be guaranteed during the pouring process of the blade root, which can improve the pouring quality and reduce the defect rate; the open-type prefabricated parts are convenient for monitoring the connection quality of the embedded bolt sleeves; according to the setting of the misalignment angle, the number of bolts can be increased by up to 90% at most, fundamentally solving the problem that the number of bolts of large wind turbine blades becomes a design bottleneck and greatly improving the ultimate bearing capacity of the blade root.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine blades, and specifically relates to a pre-embedded bolt connection structure for large wind turbine blades with a transition flange. Background Art

[0002] With the development of wind turbines towards large-scale and offshore directions, in order to improve the wind energy utilization rate, the size of the wind wheel is designed to be larger and larger, which also brings challenges to the blade design. As a key component of a wind turbine, a wind turbine blade not only captures wind energy but also bears huge loads. With the increase in blade length and weight, the loads on the blade during the operation of the wind turbine, including ultimate loads and fatigue loads, increase significantly. However, at the same time, the bearing capacity of the root connection does not increase significantly. Therefore, the root connection design often becomes a design bottleneck in the process of blade enlargement.

[0003] Traditional root connections include two types: post-drilling type and pre-embedded type. When the outer diameter of the root is fixed, by matching the bolt model and quantity, the designed bearing capacity of the root is almost stable within a fixed range. As the length increases, the load on the root will gradually increase and exceed the bearing capacity of the root. At this time, in order to ensure the safety and reliability of the blade connection, the most effective method is to increase the overall pitch diameter of the root.

[0004] The pitch diameter of the root is closely related to the hub size and the design of other components of the wind turbine. Modifying the size of the pitch diameter of the root can be described as affecting the whole by pulling one hair. Increasing the pitch diameter of the root of the wind turbine blade to install more bolts will cause a significant increase in the cost of the wind turbine blade and the wind turbine unit. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned prior art, the present invention provides a pre-embedded bolt connection structure for large wind turbine blades with a transition flange.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A large wind turbine blade pre-embedded bolt connection structure with a transition flange is used to connect the blade root of the wind turbine blade and the wind turbine hub. The blade root of the wind turbine blade is a hollow cylindrical shell, and the inner and outer surfaces of the blade root of the wind turbine blade are made of an outer skin and an inner skin respectively. Among them, the prefabricated pre-embedded blade root connection structure includes an outer ring body and an inner ring body fixed between the outer skin and the inner skin. The outer ring body is an annular structure coaxial with the blade root of the wind turbine blade assembled in sequence by a plurality of outer ring prefabricated components. The outer ring prefabricated component includes an outer prefabricated seat and an outer prefabricated column. The outer prefabricated column is inserted into the outer prefabricated seat and fixed. The outer prefabricated column has an outer hollow screw hole axially arranged. The inner ring body is an annular structure coaxial with the blade root of the wind turbine blade assembled in sequence by a plurality of inner ring prefabricated components. The inner ring body is located inside the outer ring body. The inner ring prefabricated component includes an inner prefabricated seat and an inner prefabricated column. The inner prefabricated column is inserted into the inner prefabricated seat and fixed. The inner prefabricated seat has an inner hollow screw hole axially arranged. The outer ring prefabricated component and the inner ring prefabricated component are arranged in a staggered manner. The prefabricated pre-embedded blade root connection structure also includes a transition flange. A plurality of blade root fixing holes and hub fixing holes are arranged on the transition flange. The blade root fixing holes can be aligned with each outer hollow screw hole and inner hollow screw hole. At the same time, the hub fixing holes are aligned with the connection holes on the wind turbine hub. The first fastener passes through the blade root fixing holes and each outer hollow screw hole and inner hollow screw hole to fix the transition flange and the blade root of the wind turbine blade into one body. The second fastener passes through the hub fixing holes and the connection holes on the wind turbine hub to fix the transition flange and the wind turbine hub into one body.

[0008] To optimize the above technical solution, the specific measures taken also include:

[0009] The above outer ring prefabricated components and inner ring prefabricated components correspond one by one. Correspondingly, the outer prefabricated seat and outer prefabricated column correspond to the inner prefabricated seat and inner prefabricated column one by one. The misalignment angle of the staggered arrangement of the outer ring prefabricated components and inner ring prefabricated components is 30° to 60°.

[0010] The above outer skin, inner skin, outer ring body and inner ring body are integrally pultruded by the RTM process. The outer ring body is bonded and formed by the outer prefabricated seat and outer prefabricated column. The inner ring body is bonded and formed by the inner prefabricated seat and inner prefabricated column.

[0011] One side of the above outer prefabricated seat facing the inner prefabricated seat is provided with an outer seat groove. The outer seat groove communicates with the inside and outside of the outer prefabricated seat. While improving the resin fluidity inside the outer prefabricated seat, the outside of the outer prefabricated seat can observe the outer prefabricated column located inside the outer prefabricated seat. When the outer ring body and the inner ring body are butted, the outer seat groove is closed by the inner prefabricated seat.

[0012] One side of the above inner prefabricated seat facing the outer prefabricated seat is provided with an inner seat groove. The inner seat groove communicates with the inside and outside of the inner prefabricated seat. While improving the resin fluidity inside the inner prefabricated seat, the outside of the inner prefabricated seat can observe the inner prefabricated column located inside the inner prefabricated seat. When the outer ring body and the inner ring body are butted, the inner seat groove is closed by the outer prefabricated seat.

[0013] A plurality of circular grooves are provided on the outer surfaces of the above-mentioned outer precast columns and inner precast columns, and glass fiber filaments are wound in the circular grooves.

[0014] Semicircular diversion grooves are provided on both side surfaces of the above-mentioned outer precast seats and inner precast seats. The diversion grooves are used to increase the fluidity of the resin during resin pouring and improve the connection strength between adjacent outer precast seats and between adjacent inner precast seats.

[0015] The above-mentioned adapter flange includes a blade root end flange edge and a hub end flange edge that are integrally formed. Blade root fixing holes are all provided on the blade root end flange edge, and hub fixing holes are all provided on the hub end flange edge. The blade root end flange edge and the hub end flange edge are strengthened by rib plates.

[0016] The above-mentioned first fastener and second fastener are both high-strength bolts.

[0017] The above-mentioned outer precast seats and inner precast seats are all made of glass fiber rods.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The structure of the present invention is simple, and the production process adopts traditional production techniques. Due to the use of the form of staggered arrangement of the inner and outer rings and the connection with an adapter flange, its advantages are as follows: First, the splicing joints of the precast embedded parts are alternately distributed, and the sides of the precast parts are grooved, so that the resin fluidity is ensured during the pouring process of the blade root, which can improve the pouring quality and reduce the defect rate; Second, the open-type precast parts with seat grooves are convenient for monitoring the connection quality of the embedded bolt sleeves; Third, by setting the outer ring body and the inner ring body in the present invention, according to the setting of the misalignment angle, the number of bolts can be greatly increased without changing the outer diameter size of the blade root. And according to the design range of the misalignment angle, the number of bolts is increased by 15% to 90% based on the traditional connection design, which can balance the blade root thickness and the bearing capacity, has strong designability, and fundamentally solves the problem that the number of bolts of large wind turbine blades becomes a design bottleneck, and greatly improves the ultimate bearing capacity of the blade root; Fourth, an adapter flange is used to connect the blade and the pitch bearing of the hub, which solves the problem that the bolt holes of the blade root are inconsistent with the bolt holes of the pitch bearing of the hub. While improving the bearing capacity of the blade root bolts, there is no need to change the component configuration of the original unit. Description of the Drawings

[0020] Figure 1 Isometric view of the blade root section of the present invention;

[0021] Figure 2 Enlarged view and exploded view of part A of the present invention;

[0022] Figure 3Schematic structural diagram of the outer ring prefabricated component of the present invention;

[0023] Figure 4 Schematic structural diagram of the inner ring prefabricated component of the present invention;

[0024] Figure 5 Schematic diagram of the misaligned angle of the present invention;

[0025] Figure 6 Schematic diagram of the adapter flange of the present invention;

[0026] Figure 7 Front view of the blade root section of the present invention;

[0027] Figure 8 For the present invention Figure 7 View in the directions of B - B and C - C.

[0028] The reference signs in the drawings are: outer skin 1, inner skin 2, outer ring body 3, outer prefabricated seat 31, outer prefabricated column 32, outer hollow screw hole 33, outer seat groove 34, column groove 35, diversion groove 36, inner ring body 4, inner prefabricated seat 41, inner prefabricated column 42, inner hollow screw hole 43, inner seat groove 44, adapter flange 5, blade root fixing hole 51, hub fixing hole 52, first fastener 53, second fastener 54, blade root 6 of the wind turbine blade. Detailed implementation manners

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] As Figures 1-8 shown, in a large - scale wind turbine blade embedded bolt - connection structure with an adapter flange of the present invention, the outer skin 1, inner skin 2, outer ring body 3 and inner ring body 4 are integrally pultruded by the RTM process, and then the blade root 6 of the wind turbine blade is connected to the adapter flange 5 through high - strength bolts, and finally the adapter flange 5 is connected to the pitch bearing of the hub by high - strength bolts. The outer ring body 3 and the inner ring body 4 are respectively composed of inner and outer ring prefabricated components. The outer ring prefabricated component includes an outer prefabricated seat 31 and an outer prefabricated column 32, and the inner ring prefabricated component includes an inner prefabricated seat 41 and an inner prefabricated column 42. The outer prefabricated seat 31 and the inner prefabricated seat 41 are glass fiber rods with special - shaped cross - sections. The outer prefabricated seat 31 and the outer prefabricated column 32, and the inner prefabricated seat 41 and the inner prefabricated column 42 are adhesively formed by resin, and the two components are assembled in a staggered arrangement based on the blade root circle, radially inside and outside.

[0031] The inner hole diameters of the outer precast seat 31 and the inner precast seat 41 are slightly larger than the outer diameters of the outer precast column 32 and the inner precast column 42. To ensure the bonding strength, the surfaces of the precast columns are treated with continuous grooves, in which fiberglass filaments are wound, and then bonding glue is applied to the outermost surface. The precast columns are inserted into the round holes of the precast seats. Since the precast seats have column grooves 35 with an open cross-section, the bonding quality can be inspected at the opening and the excess bonding glue can be wiped off.

[0032] The outer precast seat 31 and the inner precast seat 41 can be produced by using the mature pultrusion process to ensure the tight assembly and fit between the precast components.

[0033] The cross-sectional shapes of the outer precast seat 31 and the inner precast seat 41 are unique, which facilitates the fitting and assembly between the components. Moreover, the column groove 35 is a semi-open groove on the precast seat, and the size of the opening range is determined by the misalignment angle 11. The misalignment angle corresponds to the angular range of 30° to 60°. The setting of the angle is closely related to the root thickness and the number of bolts, and has strong designability.

[0034] Semicircular diversion grooves 36 with a radius of 1 - 3 mm are opened on the sides of the outer precast seat 31 and the inner precast seat 41, which is convenient for increasing the resin flow rate during the perfusion process and ensuring the resin fluidity.

[0035] A number of root fixing holes 51 and hub fixing holes 52 are provided on the adapter flange 5. The root fixing holes 51 can be aligned with the respective outer hollow screw holes 33 and inner hollow screw holes 43. At the same time, the hub fixing holes 52 are aligned with the connection holes on the wind turbine hub. The first fastener 53 passes through the root fixing holes 51 and the respective outer hollow screw holes 33 and inner hollow screw holes 43 to fix the adapter flange 5 and the root 6 of the wind turbine blade into one body. The second fastener 54 passes through the hub fixing holes 52 and the connection holes on the wind turbine hub to fix the adapter flange 5 and the wind turbine hub into one body.

[0036] For example, assume that the outer diameter of the root section is D , and the thicknesses of both the inner and outer skins are t = 20 mm , the minimum distance between the bolt sleeves is a = 18 mm , the outer diameter of the bolt sleeve is d = 60 mm , then the number of bolts n and the housing thickness H of the traditional root connection structure are

[0037] ,

[0038] For the root connection structure of the present invention, with the misalignment angle being θ, the number of bolts and the housing thickness are respectively:

[0039] , ,

[0040] Among them, is the increased value of the shell thickness.

[0041] Increasing ratio of the number of bolts , increasing ratio of the shell thickness .

[0042] It can be seen from this that when the misalignment angle is set to 30°, 45°, and 60°, compared with the traditional design, the number of bolts increases by 15%, 40%, and 90% respectively, and the shell thickness will increase by 39%, 55%, and 68% correspondingly.

[0043] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should be regarded as within the protection scope of the present invention.

Claims

1. A large wind turbine blade embedded bolt connection structure with an adapter flange, which is used to connect the blade root (6) of the wind turbine blade and the wind turbine hub. The blade root (6) of the wind turbine blade is a hollow cylindrical shell, and the inner and outer surfaces of the blade root (6) of the wind turbine blade are respectively made of an outer skin (1) and an inner skin (2). It is characterized in that, The prefabricated embedded blade root connection structure includes an outer ring body (3) and an inner ring body (4) fixed between the outer skin (1) and the inner skin (2). The outer ring body (3) is a ring structure coaxial with the blade root (6) of the wind turbine blade, which is formed by sequentially assembling a plurality of outer ring prefabricated components. The outer ring prefabricated component includes an outer prefabricated seat (31) and an outer prefabricated column (32). The outer prefabricated column (32) is inserted into the outer prefabricated seat (31) and fixed. The outer prefabricated column (32) has an outer hollow screw hole (33) axially arranged. The inner ring body (4) is a ring structure coaxial with the blade root (6) of the wind turbine blade, which is formed by sequentially assembling a plurality of inner ring prefabricated components. The inner ring body (4) is located inside the outer ring body (3). The inner ring prefabricated component includes an inner prefabricated seat (41) and an inner prefabricated column (42). The inner prefabricated column (42) is inserted into the inner prefabricated seat (41) and fixed. The inner prefabricated seat (41) has an inner hollow screw hole (43) axially arranged. The outer ring prefabricated components and the inner ring prefabricated components are arranged in a staggered manner. The prefabricated embedded blade root connection structure further includes a transition flange (5). A plurality of blade root fixing holes (51) and hub fixing holes (52) are provided on the transition flange (5). The blade root fixing holes (51) can be aligned with the outer hollow screw holes (33) and the inner hollow screw holes (43), and at the same time, the hub fixing holes (52) are aligned with the connection holes on the wind turbine hub. The first fastener (53) passes through the blade root fixing holes (51) and the outer hollow screw holes (33) and the inner hollow screw holes (43), so that the transition flange (5) is fixed to the blade root (6) of the wind turbine blade as a whole. The second fastener (54) passes through the hub fixing holes (52) and the connection holes on the wind turbine hub, so that the transition flange (5) is fixed to the wind turbine hub as a whole; the outer ring prefabricated components and the inner ring prefabricated components correspond one by one. Correspondingly, the outer prefabricated seat (31) and the outer prefabricated column (32) correspond to the inner prefabricated seat (41) and the inner prefabricated column (42) one by one. The stagger angle of the staggered arrangement of the outer ring prefabricated components and the inner ring prefabricated components is 30° to 60°; an outer seat groove (34) is opened on one side of the outer prefabricated seat (31) facing the inner prefabricated seat (41). The outer seat groove (34) communicates with the inside and outside of the outer prefabricated seat (31). While improving the resin fluidity inside the outer prefabricated seat (31), the outer side of the outer prefabricated seat (31) can observe the outer prefabricated column (32) located inside the outer prefabricated seat (31). When the outer ring body (3) and the inner ring body (4) are butted, the outer seat groove (34) is closed by the inner prefabricated seat (41); an inner seat groove (44) is opened on one side of the inner prefabricated seat (41) facing the outer prefabricated seat (31). The inner seat groove (44) communicates with the inside and outside of the inner prefabricated seat (41). While improving the resin fluidity inside the inner prefabricated seat (41), the outer side of the inner prefabricated seat (41) can observe the inner prefabricated column (42) located inside the inner prefabricated seat (41). When the outer ring body (3) and the inner ring body (4) are butted, the inner seat groove (44) is closed by the outer prefabricated seat (31).

2. The embedded bolt connection structure of a large wind turbine blade with a transition flange according to claim 1, wherein: The outer skin (1), inner skin (2), outer ring body (3) and inner ring body (4) are integrally formed by RTM process. The outer ring body (3) is formed by bonding an outer prefabricated base (31) and an outer prefabricated column (32). The inner ring body (4) is formed by bonding an inner prefabricated base (41) and an inner prefabricated column (42).

3. The embedded bolt connection structure of a large wind turbine blade with a transition flange according to claim 2, characterized in that: A plurality of circles of column grooves (35) are arranged on the outer surfaces of the outer prefabricated column (32) and the inner prefabricated column (42), and glass fiber filaments are wound in the column grooves (35).

4. A pre-embedded bolt connection structure for a large wind turbine blade with an adapter flange according to claim 3, characterized in that: Semicircular flow guide grooves (36) are formed on both side surfaces of the outer prefabricated base (31) and the inner prefabricated base (41). The flow guide grooves (36) are used to increase the fluidity of the resin during resin perfusion, improve the perfusion quality and ensure the connection strength between adjacent outer prefabricated bases (31) and between adjacent inner prefabricated bases (41).

5. The embedded bolt connection structure of a large wind turbine blade with an adapter flange according to claim 4, characterized in that: The adapter flange (5) includes a blade root end flange edge and a hub end flange edge which are integrally formed. Blade root fixing holes (51) are arranged on the blade root end flange edge, and hub fixing holes (52) are arranged on the hub end flange edge. The blade root end flange edge and the hub end flange edge are strengthened by rib plates.

6. The embedded bolt connection structure of a large wind turbine blade with an adapter flange according to claim 5, characterized in that: The first fastener (53) and the second fastener (54) are both high-strength bolts.

7. A pre-embedded bolt connection structure for a large wind turbine blade with an adapter flange according to claim 1, characterized in that: The outer prefabricated base (31) and the inner prefabricated base (41) are both made of glass fiber rods.

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