An anti-fracture connection structure between a wind turbine blade and a pitch bearing

Abstract

The present invention discloses an anti-fracture connection structure between a wind turbine blade and a pitch bearing, including the blade and the pitch bearing. The root of the blade is connected to the inner ring of the pitch bearing through a fixing member. The feature is that at least two circles of fixing hole groups are arranged radially along the root of the blade, and embedded positioning sleeves are arranged in the fixing holes. Through holes are arranged on the inner ring of the pitch bearing corresponding to the fixing hole groups, and the fixing member passes through the through holes and connects the embedded positioning sleeves. By arranging multiple circles of fixing hole groups in a grouped manner between the blade and the pitch bearing to form a "grid" connection structure, without increasing the number of bolts and the mass of a single bolt, the stress concentration phenomenon can be effectively reduced only through structural optimization, and the anti-fracture performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine assembly, and in particular to an anti-fracture connection structure between a wind turbine blade and a pitch bearing. Background Art

[0002] In recent years, with the rapid development of the wind power industry, the demand for high-performance and long-sized blades by wind turbines has been increasing day by day, and the blades have begun to develop towards large-scale.

[0003] As the size and weight of the blades continue to increase, the loads borne by the blades are also getting larger and larger, making the connection strength between the root of the blade and the pitch bearing a bottleneck in blade development. Although the design size of the blades has been greatly improved in recent years, the design of the root connection structure of the blades still retains the traditional single-row bolt connection design concept, that is, a circle of bolt sleeves is embedded at the root of the blade, and the pitch bearing is connected through double-headed bolts, and the anti-corrosion performance of the blade bolts is increased by internal and external reinforcement with fiberglass. With the rapid development of the wind power industry, large megawatt-class blades have emerged. As the blade profile increases, the traditional connection method between the blade and the pitch bearing can no longer meet the performance requirements for strength, stiffness, anti-fatigue strength, and anti-corrosion at the connection between the blade and the pitch bearing. It is difficult to meet the requirements of blade large-scale according to the traditional single-row bolt connection design. The traditional solution is to increase the size of the blade root and the number of root connection bolts, which will further increase the weight of the blade, the size of the root, and the size of the pitch bearing connected thereto, greatly increasing the development cost of the blade and the wind turbine, and also increasing the difficulty of transportation and hoisting. At present, the connection design between the blade root and the pitch bearing has become a common problem in blade large-scale.

[0004] For example, Chinese patent document (Publication No.: CN102748246A) discloses a "connection structure between a wind turbine blade and a pitch bearing", which includes a wind turbine blade and a pitch bearing. A flange gasket is provided between the wind turbine blade and the pitch bearing. Long screw holes and short screw holes are provided at intervals on the end face of the root of the wind turbine blade. Two circles of nut holes are provided on the side surface of the root of the wind turbine blade along the circumferential direction of the blade. Nuts are provided in the nut holes. The nuts in the inner circle of nut holes are fastened in cooperation with the short screws, and the nuts in the outer circle of nut holes are fastened in cooperation with the outer screws. The present invention fixedly connects the wind turbine blade, the flange gasket, and the pitch bearing together by installing long screws and short screws at intervals on the end face of the root of the wind turbine blade.

[0005] In the above technical solution, although the traditional single-row bolt connection is optimized to an alternating arrangement of long and short bolts, the problem of stress concentration caused by the self-weight and wind pressure of the blade root is still not solved. As the operation time of the fan increases, the fracture risk at the blade root will continue to amplify, and encountering strong instantaneous wind will further accelerate the occurrence of fatigue fracture at the blade root. Summary of the Invention

[0006] Aiming at the problem of stress concentration and subsequent fatigue fracture between the existing fan blade and the pitch bearing mentioned in the background technology, the present invention provides an anti-fracture connection structure for the wind turbine blade and the pitch bearing. By arranging multiple circles of fixing hole groups in groups between the blade and the pitch bearing to form a "grid" connection structure, without increasing the number of bolts and the mass of a single bolt, the stress concentration phenomenon is effectively reduced only through structural optimization, and the anti-fracture performance is improved.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An anti-fracture connection structure for a wind turbine blade and a pitch bearing, including a blade and a pitch bearing. The root of the blade is connected to the inner ring of the pitch bearing through a fixing member. The feature is that at least two circles of fixing hole groups are arranged radially along the root of the blade, and pre-embedded positioning sleeves are arranged in the fixing holes. Through holes corresponding to the fixing hole groups are arranged on the inner ring of the pitch bearing, and the fixing member passes through the through holes and connects the pre-embedded positioning sleeves. The pre-embedded positioning sleeves are integrally vacuum-injected with the blade root during the production and manufacturing of the blade, and are connected to the pitch bearing through connecting bolts and connecting nuts, forming an integral multi-circle bolt connection structure between the blade root and the pitch bearing. Compared with the traditional connection structure, this progressive connection method can effectively disperse stress, ensure that the shear force at the root of the large-size blade can be dispersed and act on the bolts of all fixing hole groups, and effectively increase the anti-fracture performance.

[0009] Preferably, the fixing hole group includes a first fixing hole group close to the outer contour of the blade and a second fixing hole group close to the inner cavity of the blade. The first fixing hole group includes outer ring fixing holes, and the second fixing hole group includes inner ring fixing holes. The outer ring fixing holes are spaced from the inner ring fixing holes. One inner ring fixing hole is arranged on each side of any outer ring fixing hole, and the outer ring fixing hole and the two inner ring fixing holes are distributed at the three endpoints of an isosceles triangle. The first fixing hole group and the second fixing hole group are respectively the outermost bolt hole group and the innermost bolt hole group on the blade, and the main load-bearing point of the blade self-weight is the outermost first fixing hole group. Especially, when the blade encounters high instantaneous wind force, the stress concentration at the first fixing hole group reaches the peak. Using a double-circle bolt distributed in an isosceles triangle can evenly disperse the load and transmit it from the outside to the inside, optimizing the mechanical properties of the connection structure.

[0010] Preferably, reinforcing grooves are respectively arranged between the outer ring fixing holes and the inner ring fixing holes on both sides. A load transfer member is arranged in the reinforcing groove. The load transfer member includes a middle rod fixedly arranged in the reinforcing groove. One end of the middle rod is provided with a first fixing sleeve sleeved on the outer ring fixing hole, and the other end of the middle rod is provided with a second fixing sleeve sleeved on the inner ring fixing hole. The reinforcing groove is a shallow groove, and its main function is to fit and install the load transfer member. The load transfer member is used to connect the first fixing hole group and the second fixing hole group. During normal operation, the first fixing hole group and the second fixing hole group jointly bear the blade load, and the two rings of fixing hole groups form a "force-bearing whole" to resist the load; when encountering high instantaneous wind force, the load transfer member can transfer the load borne by the first fixing hole group, which mainly bears the stress, to the second fixing hole group, and utilize the stability characteristics of the triangle to disperse the internal stress of the "force-bearing whole" composed of the two rings of fixing hole groups, reduce the stress concentration phenomenon of the first fixing hole group, and improve the anti-fracture performance of the overall connection structure.

[0011] Preferably, the fixing member of the first fixing sleeve and the inner ring fixing hole are in interference socket connection, and the fixing member of the second fixing sleeve and the outer ring fixing hole are in interference socket connection. The load transfer member can be in interference connection with the fixing members at both ends, ensuring that the fixing members in two adjacent circles can support each other and disperse the load, and enhancing the overall anti-shear performance.

[0012] Preferably, a converging rib is arranged between the two inner ring fixing holes on both sides of an outer ring fixing hole. Both ends of the converging rib are fixedly connected to the second fixing sleeves on the inner ring fixing holes respectively. The converging rib is used to increase the connection strength when the two inner ring fixing holes are subjected to huge loads, so that the bolts in the outer ring fixing holes and the bolts in the inner ring fixing holes form a complete triangular structure, and further improve the mechanical properties of the connection structure.

[0013] Preferably, the converging rib is arranged in an arc shape away from the first fixing hole group, and the width of the middle part of the converging rib is greater than the widths of both ends. The arc structure of the converging rib can better transfer the loads of the bolts at both ends and complete the support through the wider middle part, greatly improving the anti-shear ability of the "force-bearing whole" and avoiding cracking at the connection between the blade and the pitch bearing.

[0014] Preferably, the adjacent fixing hole groups are concentrically arranged. The concentrically arranged fixing hole groups can evenly disperse the loads from the blade and ensure the connection stability in the case of a large increase in the blade specifications.

[0015] Therefore, the present invention has the following beneficial effects: (1) By arranging multiple sets of fixing holes in groups between the blade and the pitch bearing to form a "grid" - type connection structure, without increasing the number of bolts and the mass of a single bolt, the stress concentration phenomenon can be effectively reduced only through structural optimization, and the anti - fracture performance is improved; (2) When encountering high - intensity instantaneous wind force, the load - transfer member can transfer the load borne by the first set of fixing holes, which mainly bears stress, to the second set of fixing holes, and utilize the stability characteristics of a triangle to disperse the internal stress of the "force - bearing whole" composed of two sets of fixing holes, reduce the stress concentration phenomenon of the first set of fixing holes, and improve the anti - fracture performance of the overall connection structure; (3) The converging rib is used to increase the connection strength when the two inner - ring fixing holes are subjected to huge loads, so that the bolts in the outer - ring fixing holes and the bolts in the inner - ring fixing holes form a complete triangular structure, further improving the mechanical properties of the connection structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the front view of the blade root in Embodiment 1.

[0017] Figure 2 is Figure 1 the sectional view at A - A in

[0018] Figure 3 is Figure 1 the structural schematic diagram of the load - transfer member in

[0019] In the figure: 1. Blade, 2. Pitch bearing, 21. Inner ring, 3. Embedded positioning sleeve, 4. Fixing member, 5. First set of fixing holes, 51. Outer - ring fixing holes, 6. Second set of fixing holes, 61. Inner - ring fixing holes, 7. Load - transfer member, 71. Middle rod, 72. First fixing sleeve, 73. Second fixing sleeve, 8. Converging rib. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following further describes the present invention in combination with the drawings and specific embodiments. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0022] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral one; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the internal communication between two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] Embodiment 1

[0024] As Figure 1 、 2 shown, an anti-fracture connection structure between a wind turbine blade and a pitch bearing includes a blade 1 and a pitch bearing 2. The root of the blade 1 is connected to the inner ring 21 of the pitch bearing 2 through a fixing member 4. The feature is that at least two circles of fixing hole groups are arranged radially along the root of the blade 1, and pre-embedded positioning sleeves 3 are arranged in the fixing holes. Through holes are arranged on the inner ring 21 of the pitch bearing corresponding to the fixing hole groups, and the fixing member 4 passes through the through holes and connects to the pre-embedded positioning sleeves 3. The fixing hole group includes a first fixing hole group 5 near the outer contour of the blade 1 and a second fixing hole group 6 near the inner cavity of the blade 1. The first fixing hole group 5 includes outer ring fixing holes 51, and the second fixing hole group 6 includes inner ring fixing holes 61. The outer ring fixing holes 51 are spaced apart from the inner ring fixing holes 61. One inner ring fixing hole 61 is arranged on each side of any outer ring fixing hole 51, and the outer ring fixing hole 51 and the two inner ring fixing holes 61 are distributed at the three endpoints of an isosceles triangle. Adjacent fixing hole groups are concentrically arranged.

[0025] The pre-embedded positioning sleeve 3 is integrally vacuum-injected with the root of the blade 1 during the production and manufacturing of the blade 1, and is connected to the pitch bearing 2 through connection bolts and connection nuts, forming an integral structure of a multi-circle bolt connection between the blade root and the pitch bearing 2. Compared with the traditional connection structure, this progressive connection method can effectively disperse stress, ensuring that the shear force at the root of the large-size blade 1 can be dispersed and act on the bolts of all fixing hole groups, effectively increasing the anti-fracture performance. The first fixing hole group 5 and the second fixing hole group 6 are respectively the outermost bolt hole group and the innermost bolt hole group on the blade 1, and the main load-bearing point of the self-weight of the blade 1 is the outermost first fixing hole group 5. Especially when the blade 1 encounters high instantaneous wind force, the stress concentration at the first fixing hole group 5 reaches the peak. The double-circle bolts arranged in an isosceles triangle can make the load evenly dispersed and transmitted from the outside to the inside, optimizing the mechanical properties of the connection structure. The concentrically arranged fixing hole groups can evenly disperse the load from the blade 1, ensuring the connection stability when the blade 1 specifications are greatly improved.

[0026] Reinforcing grooves are respectively arranged between the outer ring fixing holes 51 and the inner ring fixing holes 61 on both sides. A load transfer member 7 is arranged in the reinforcing groove. The load transfer member 7 includes a middle rod 71 fixedly arranged in the reinforcing groove. One end of the middle rod 71 is provided with a first fixing sleeve 72 sleeved on the outer ring fixing hole 51, and the other end of the middle rod 71 is provided with a second fixing sleeve 73 sleeved on the inner ring fixing hole 61. A converging rib 8 is arranged between the two inner ring fixing holes 61 on both sides of an outer ring fixing hole 51. Both ends of the converging rib 8 are fixedly connected to the second fixing sleeves 73 on the inner ring fixing holes 61. The converging rib 8 is arranged in an arc shape away from the first fixing hole group 5, and the width of the middle part of the converging rib 8 is greater than the widths of both ends.

[0027] As Figure 3 shown, the reinforcing groove is a shallow groove, and its main function is to fit and install the load transfer member 7. The load transfer member 7 is used to connect the first fixing hole group 5 and the second fixing hole group 6. During normal operation, the first fixing hole group 5 and the second fixing hole group 6 jointly bear the load of the blade 1, and the two circles of fixing hole groups form a "force-bearing whole" to resist the load; when encountering high instantaneous wind force, the load transfer member 7 can transfer the load borne by the first fixing hole group 5, which mainly bears stress, to the second fixing hole group 6, and utilize the stability characteristics of the triangle to disperse the internal stress of the "force-bearing whole" formed by the two circles of fixing hole groups, reduce the stress concentration phenomenon of the first fixing hole group 5, and improve the anti-fracture performance of the overall connection structure. The converging rib 8 is used to increase the connection strength when the two inner ring fixing holes 61 are subjected to huge loads, so that the bolts in the outer ring fixing holes 51 and the bolts in the inner ring fixing holes 61 form a complete triangular structure, further improving the mechanical properties of the connection structure. The arc-shaped structure of the converging rib 8 can better transfer the loads of the bolts at both ends and complete the support through the wider part in the middle, greatly improving the anti-shear ability of the "force-bearing whole" and avoiding rupture at the connection between the blade 1 and the pitch bearing 2.

[0028] In this embodiment, the fixing member 4 adopts a double-headed bolt. By optimizing the distribution position of the fixing member 4 between the root of the blade 1 and the pitch bearing 2, the anti-fracture performance of the blade 1 is improved. Specifically, in this embodiment, the outer ring fixing holes 51 and the inner ring fixing holes 61 are used in combination, and two circles of spaced fixing members 4 are used for connection. A grid-shaped load-bearing structure is formed by the mutually connected bolts, effectively avoiding the occurrence of stress concentration phenomenon and improving the anti-fracture performance of the connection structure.

[0029] Except for the above embodiments, within the scope disclosed in the claims and the specification of the present invention, the technical features of the present invention can be reselected and combined to form new embodiments, which can be realized by those skilled in the art without creative labor. Therefore, these embodiments not detailedly described in the present invention should also be regarded as specific embodiments of the present invention and within the protection scope of the present invention.

Claims

1. An anti-fracture connection structure between a wind turbine blade and a pitch bearing, comprising a blade and a pitch bearing, wherein the root of the blade is connected to the inner ring of the pitch bearing through a fixing member, and the feature is that, At least two sets of fixing holes are arranged radially along the root of the blade. Embedded positioning sleeves are arranged in the fixing holes. Through holes are arranged on the inner ring of the pitch bearing corresponding to the sets of fixing holes. The fixing members pass through the through holes and are connected to the embedded positioning sleeves. The set of fixing holes includes a first set of fixing holes close to the outer contour of the blade and a second set of fixing holes close to the inner cavity of the blade. The first set of fixing holes includes outer ring fixing holes, and the second set of fixing holes includes inner ring fixing holes. The outer ring fixing holes are arranged at intervals from the inner ring fixing holes. Reinforcing grooves are respectively arranged between the outer ring fixing holes and the inner ring fixing holes on both sides. Load transfer members are arranged in the reinforcing grooves. A converging rib is arranged between the two inner ring fixing holes on both sides of an outer ring fixing hole.

2. The anti-fracture connection structure between a wind turbine blade and a pitch bearing according to claim 1, wherein, One inner ring fixing hole is arranged on each side of any outer ring fixing hole. The outer ring fixing hole and the two inner ring fixing holes are distributed at the three endpoints of an isosceles triangle.

3. The anti-fracture connection structure between a wind turbine blade and a pitch bearing according to claim 2, wherein, The load transfer member includes a middle rod fixedly arranged in the reinforcing groove. A first fixing sleeve sleeved on the outer ring fixing hole is arranged at one end of the middle rod, and a second fixing sleeve sleeved on the inner ring fixing hole is arranged at the other end of the middle rod.

4. The anti-fracture connection structure between a wind turbine blade and a pitch bearing according to claim 2, wherein, Both ends of the converging rib are fixedly connected to the second fixing sleeves on the inner ring fixing holes respectively.

5. The anti-fracture connection structure between a wind turbine blade and a pitch bearing according to claim 4, wherein, The converging rib is arranged in an arc shape away from the first set of fixing holes. The width of the middle part of the converging rib is greater than the widths of both ends.

6. The anti-fracture connection structure between a wind turbine blade and a pitch bearing according to claim 3, wherein, The first fixing sleeve is in interference fit with the fixing member of the inner ring fixing hole, and the second fixing sleeve is in interference fit with the fixing member of the outer ring fixing hole.

7. The anti-fracture connection structure between a wind turbine blade and a pitch bearing according to any one of claims 1-6, wherein, Adjacent sets of fixing holes are concentrically arranged.

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