GB2603463A

GB2603463A - Bearing Assembly for Wind Turbines

Info

Publication number: GB2603463A
Application number: GB2101052.5A
Authority: GB
Inventors: O'flynn Donal
Original assignee: Donal Oflynn
Current assignee: Donal Oflynn
Priority date: 2021-01-26
Filing date: 2021-01-26
Publication date: 2022-08-10
Also published as: WO2022162000A1; GB202101052D0

Abstract

A bearing assembly for a wind turbine is disclosed. The bearing assembly 500a comprising an inner race 510 and an outer race 520; wherein at least one of the inner race or the outer race comprises a plurality of interconnected struts 750, the struts being interconnected by node 650 members to form a lattice structure. A turbine blade assembly and a wind turbine comprising the bearing assembly are also disclosed. The bearing strut and node macrostructure is light due to the low density material used, resulting in the loads on the turbine nacelle, tower and base. This enables more convenient handling of the assembly. The macrostructure may be robotically assembled, cutting down on human error and cost. Turbine blades in accordance with the invention may be reused.

Description

I

BEARING ASSEMBLY FOR WIND TURBINES

Field of the Invention

The present invention relates to wind turbines, in particular but not limited to bearing assemblies for rotatable connections between wind turbine components and lattice macrostructures.

Background to the Invention

Among environmentally friendly energy sources presently available, wind power is generally considered to be one of the cleanest. In this regard, wind turbines have gained increased attention. Wind turbines generate electricity by effectively harnessing energy in the wind via a rotor having a set of rotor blades that turns a gearbox and generator, thereby converting mechanical energy to electrical energy that may be deployed to a utility grid. The construction of a modern rotor blade generally includes skin or shell components, span-wise extending spar caps, and one or more shear webs. Present technology uses several moulds to fabricate the various pieces of the blade that are bonded together in large resin-infused moulds. Such finished blades are relatively heavy and include a hardened shell encasing the moulded hardened shear webs or spar caps. This leads to difficulty in transportation and assembly of the wind turbines. Further, the size, shape, and weight of rotor blades are factors that contribute to energy efficiencies of wind turbines. An increase in rotor blade size increases the energy production of a wind turbine, while a decrease in weight furthers the efficiency of a wind turbine. Furthermore, as rotor blade sizes grow, extra attention needs to be given to the structural integrity of the rotor blades and means of connection to turbine hubs. Accordingly, efforts to increase rotor blade length, decrease rotor blade weight, and increase rotor blade strength, while also improving rotor blade aerodynamics, aid in the continuing growth of wind turbine technology and the adoption of wind energy as an alternative energy source. There is therefore a desire for an improved connection means for connecting rotor blades to a wind turbine. Such connection means should improve overall system efficiency while being inexpensive to fabricate and providing a long lifetime.

Summary of the Invention

In accordance with an aspect of the invention there is provided a bearing assembly for a wind turbine, wherein the bearing assembly comprises an inner race and an outer race; wherein at least one of the inner race or the outer race comprises a plurality of interconnected struts, the struts being interconnected by node members to form a lattice structure.

It will be understood that that the terminology inner race and an outer race corresponds to the inner and outer annular members of a bearing.

Optionally, the lattice structure is housed within an annular trough formed in at least one of the inner race or the outer race.

Optionally, the plurality of interconnected struts are provided in the inner race.

Optionally, the plurality of interconnected struts are provided in the outer race.

Optionally, a plurality of interconnected struts are provided in both inner and outer races.

Optionally, a subset of the nodes are adapted to receive strut members extending from an external source or component, for example but not limited to, a turbine blade, a turbine hub, a turbine tower, a turbine shaft, a turbine shaft head, a turbine teeter shaft.

Optionally, each node of the subset is adapted to receive at least one external strut member.

Optionally, the nodes of the subset define an upper layer of nodes Optionally, the subset nodes and their respective interconnecting struts are at least partially encased by an encasing material.

Optionally, the encasing material is a polymeric encasing material.

Optionally, the polymeric encasing material is a fibre reinforced polymeric encasing material.

Optionally, the encasing material is a metal or metal alloy encasing material, wherein the respective nodes and struts are located within suitable node-receiving cavities and strut-receiving channels formed within said metal or metal alloy encasing material.

Optionally, encasing material is the material from which the bearing race is formed.

Optionally, where the encasing material is polymeric, the bearing race comprises a substantially U-shaped annular trough which contains said polymeric encasing material and lattice structure, optionally wherein the substantially U-shaped annual trough is made from metal or metal alloy, and optionally wherein the polymeric encasing material introduced into the annular trough in a melted form. In this optional arrangement, the outer surfaces of the U-shaped annular trough defines the bearing surfaces.

Optionally, one or more subset nodes protrude from the encasing material.

Optionally, one or more subset nodes is/are located within the encasing material at one end of an open-end channel extending between the node and the surface of the encasing material, the channel being configured to receive an external strut member inserted therein.

Optionally, the non-subset nodes and their respective interconnecting strut members are substantially encased in the encasing material.

Optionally, the polymeric encasing material is introduced to the annular trough in melted form.

Optionally, the polymeric encasing material is a thermoplastic.

Optionally, the thermoplastic is polyetheretherketone (PEEK).

Optionally, the PEEK is carbon-fibre reinforced PEEK.

Optionally, the polymeric encasing material is a vitrimer.

Optionally, the nodes are formed from fiber reinforced polymer.

Optionally, the nodes are formed from fiber reinforced PEEK.

Optionally, the nodes are formed from Polyetherimide.

Optionally, the struts are formed from fiber reinforced polymer.

Optionally, the struts are formed from fiber reinforced PEEK.

Optionally, the struts are formed from Polyetherimide (PEI).

Optionally, the struts can be formed from any one or more of fibre reinforced polymers, such as but not limited to, CFRP, CRP, CFRTP GFRP, BFRP, or mixtures thereof.

Optionally, each node is connected to four other nodes.

Optionally, each node is configured to interconnect with any number n of nodes through the provision of n strut receiving formations.

Optionally, the strut receiving formations are adapted to receive and engage an end of a strut.

Optionally, struts and respective strut receiving formations are provided with suitable corresponding mutual engagement means.

Optionally, the mutual engagement means comprises a Hirth coupling.

Optionally, the mutual engagement means is a snap-fit engagement means.

Optionally, struts and nodes are configured for bonding or fusing by melting.

Optionally, subset nodes are reversibly bondable to external struts when interconnected to form a continuous external component to bearing interface structure.

In a second aspect of the invention, there is provided a bearing assembly in accordance with the first aspect of the invention, wherein the bearing assembly is a teeter bearing for a two-blade wind turbine hub, wherein the subset nodes of the inner bearing race are adapted to receive external strut members extending from a horn of a turbine shaft head or from a teeter shaft; and wherein the outer bearing race is configured to engage a rotor hub, or a blade root.

In a third aspect of the invention, there is provided a bearing assembly in accordance with the first aspect of the invention, the bearing being a yaw bearing for a wind turbine, wherein the subset nodes of the inner race are adapted for connection to external struts extending from a turbine tower, and wherein and the outer race is adapted for connection to a turbine nacelle.

According to a fourth aspect of the invention, there is provided a turbine blade comprising a blade tip, a blade root and a connection means for connecting said blade to a bearing assembly of the first aspect of the invention; wherein the connection means comprises a plurality of struts having a first portion and a second portion, wherein the first portion of each strut is embedded within the blade and wherein the second portion is a free end that projects from the blade root; and wherein the free end of each strut is configured for connection with a corresponding node provided in an race of the bearing assembly.

Optionally, each strut is integrally formed with the blade.

According to a further aspect of the invention, there is provided a wind turbine assembly comprising one or more bearing assemblies in accordance with the aspects of the invention.

The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification.

Various aspects of the invention will now be described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the scope of the present invention. Accordingly, each example herein should be understood to have broad application, and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. In particular, unless otherwise stated, dimensions and numerical values included herein are presented as examples illustrating one possible aspect of the claimed subject matter, without limiting the disclosure to the particular dimensions or values recited. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

Language such as "including", "comprising", "having", "containing", or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word "comprise" or variations thereof such as "comprises" or "comprising" will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, the words "typically" or "optionally" are to be understood as being intended to indicate optional or non-essential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

Directional references such as "up", "down", "vertical", "horizontal", "above", "below", "upper", "lower", inner, outer, are to be understood in the context of the normal orientation of a wind turbine and major components thereof With reference to the Figures, examples of the present invention will now be described.

Brief Description of the Drawings

Figures la and lb are schematic cut-away drawings of exemplary wind turbine structures; Figure 2 is an illustration of a turbine blade; Figure 3 is a schematic illustration of a bearing element in accordance with the invention shown in partial cross section; Figure 4a is a schematic drawing of an exemplary strut and node macrostructure in accordance with the invention; Figure 4b is a force diagram of the strut and node macrostructure of Figure 4a; Figure 5 is a plan view of the exemplary strut and node macrostructure of Figure 4a; Figure 6 is a detailed view of an exemplary node in accordance with the invention; Figure 7a is a schematic illustration of attachment of turbine blade to a bearing element in accordance with the invention: Figures 7b and 7c are schematic illustrations of exemplary strut and node lattice structures; Figures 8 and 8b are schematic illustrations of a bearing element of the invention in use as a yaw bearing; and Figure 9 is a schematic illustration of attachment of turbine blade to a bearing element in accordance with the invention, the bearing element being a hinge or teeter bearing of a two-bladed turbine at the hub-bearing interface.

Description

With reference to Figures la and lb, horizontal axis turbines generally comprise a tower 10, a nacelle 20, a rotor hub 30, a plurality of rotor blades 40, and a generator 60. Most commonly, two or three rotor blades are employed.

The nacelle 20 houses the rotor hub 30 assembly and the generator 60. The rotor hub 30 is connected to a low speed shaft (not shown). The low speed shaft extends to a gearbox (not shown) which in turn drives a high-speed shaft (not shown) that drives the generator 60.

With reference to Figure 1c, nacelle 20 is pivotally mounted to the tower 10 via a yaw system 70 such that the nacelle can be rotated relative the tower 10.

With reference to Figure 1c, yaw system 70 comprises a yaw bearing 71 connected between the nacelle 20 and an annular bull gear 72 fixed to the tower, and a pinion gear 73, whereby operation of a yaw motor 74 drives pinion gear 73 to rotate the nacelle 20 relative the bull gear 72.

With reference to Figure 1c, to stabilize the yaw bearing 71 and thus the nacelle 20 against rotation, yaw system 70 further comprises a yaw brake system 75 comprising a brake calliper 76 having pistons 77 which engages a flat circular brake disc 78 that is fixed to either the bull gear 72 or the tower 10 structure.

With reference to Figure 2, a rotor blade 40 comprises a hollow, slender profile, a blade tip 41 and a blade root 42, the profile formed by two asymmetrically shaped shell structures 43, 44 glued together to form the rigid blade.

Shell structures 43, 44 are generally made from fibre composite materials and sandwich composite materials with foams or woods as core materials. Since rotor blades 40 are slender beam-like structures and are exposed to dynamic loads, the materials used in their manufacture must be lightweight, have a high-strength-to-weight-ratio and good fatigue properties. Typically, glass fibre mats with unidirectional, biaxial or triaxial fibre orientation with different material properties, moduli and strengths are used. Some blade manufacturers also use carbon fibres to strengthen the load carrying structure, due to the higher tensile moduli of carbon fibres compared to glass fibres. Polyesters and epoxies are used as resins to impregnate the fibre mats.

Typically, the fibre mats are layered into suitably shaped moulds by hand. Subsequently, the fibre mats are covered with plastic foils for vacuum forming. Then, an infusion process starts, whereby resin flows because of the atmospheric overpressure into the mould. This process, known as Vacuum Assisted Resin Transfer Moulding (VARMT), is the predominant method of forming turbine blades due to the resultant laminate quality and the relatively low manufacturing cost.

With reference to Figure lb, in the prior art, each blade 40 is connected at its root 42 to the inner race 51 of a bearing assembly 50, with the outer race 52 of said bearing assembly being fixed to the rotor hub 30 assembly. Connection of each blade 40 to the inner race 51 is via an array of bolts 60 that extend through an annular flange 45 provided around the blade root 42 and which engage said inner bearing race 51.

With reference to Figures la and lb, the inner bearing race 51 is provided with teeth arranged around its inner circumference, the teeth configured to engage with a pitch system 80 that is operable on said inner bearing race to turn or pitch the blade 40 relative the wind direction so that the rotor hub speed can be controlled, for example to maintain a desired rotation velocity, or to feather the rotor blades in order help to prevent the rotor hub 30 from turning in winds that are too high or too low to produce electricity.

Typically, braking systems (not shown) to brake the rotor hub 30 are also provided. 20 With reference to Figure 3, in accordance with the invention there is provided a bearing assembly 500A having an inner race 510 and outer race 520. In the present example, the inner race 510 is configured for connection with a turbine blade and the outer race 520 is configured for connection to a rotor hub. Thus in this example, the bearing assembly is a rotor/pitch bearing for connection of a rotor 40 to a rotor hub 30.

With reference to Figure 7a the inner race 510 comprises a plurality of interconnected nodes 600. Nodes 600 are interconnected by strut members 700.

The interconnected nodes 600 form a lattice macrostructure. The lattice structure is housed within the inner race 510. Preferably, the lattice structure is encased within the inner race. As the macrostructure uses discrete lattice materials as its building blocks, delaminafion is mitigated. It will be understood that in embodiments, the outer race 520 may also, or alternatively, comprise a lattice structure comprising a plurality of interconnected nodes 600 as presently described with respect to the inner race 510.

A subset 650 of nodes 600 are adapted to receive external strut members 750. For simplicity, such nodes are given the reference numeral 650. Each subset node 650 is adapted to receive at least one external strut member 750. Optionally, the subset 650 of nodes define an upper layer of nodes.

In accordance with embodiments of the invention, the bearing race may be formed from metal, metal alloy or polymer. Optionally, the polymer may be fibre reinforced polymer.

In examples, the nodes 600 and their respective interconnecting strut members 700 are described as being substantially encased in the polymeric material 900 of the bearing race 510.

With reference to Figure 3, in examples, the inner race 510 may comprise a substantially U-shaped annular trough 511 which contains the polymeric material 900 and lattice structure. The U-shaped annular trough is preferably made from metal or metal alloy. In this embodiment, the polymeric material 900 is optionally introduced into the annular trough 511 in a melted form. In this optional arrangement, the outer surfaces of the U-shaped annular trough 511 define the bearing surfaces.

Subset nodes 650 adapted to receive external strut members 750 are at least partially surrounded in the encasing material 900, for example the polymeric casing material. Such nodes 650 may protrude from the encasing material, or may be located within the encasing material 900 at one end of an open-end channel extending between the node 650 and the surface of the encasing material, the channel being configured to receive an external strut member 750 inserted therein.

With reference to Figure 3, which is a schematic cut away drawing of an exemplary bearing assembly 500A, there is shown by way of example a cross-section A of an inner race 510 in which a strut 700 is encased in fiber reinforced polymeric encasing material 900 and the node 650 is exposed at the surface of the fiber reinforced polymeric casing material 900. Alternatively, as shown in cross-section B, a node 650 may be located within the fiber reinforced polymeric encasing material 900, with an external strut member 750 extending into engagement with the node 650 through a portion of the encasing material 900. In Figure 3, suitable bearing rolling elements 550 are shown.

In each arrangement, nodes 650 act as a starting point to form a continuum of a structure Optionally, in examples, the fiber reinforced polymeric encasing material is a thermoplastic.

Optionally, the thermoplastic polyetheretherketone (PEEK).

Optionally, the PEEK material is carbon-fibre reinforced PEEK.

Optionally, in examples, the polymeric encasing material is a vitrimer.

Where the encasing material is a metal or metal alloy encasing material, the respective nodes and struts are located within suitable node-receiving cavities and strut-receiving channels formed within said metal or metal alloy encasing material.

Optionally, the metal or metal alloy encasing material is the material from which the bearing race is formed.

Optionally, in examples, nodes 600, 650 are formed from PEEK. Optionally, the PEEK material is carbon-fibre reinforced PEEK.

Optionally, in examples, struts 700 are formed from carbon-fibre reinforced PEEK Optionally, in examples, struts 700 are formed from Polyetherimide (PEI).

Optionally, struts can be formed from any one or more of fibre reinforced polymers, such as but not limited to, CFRP, CRP, CFRTP GFRP, BFRP, or mixtures thereof.

With reference to Figure 7a, in the example shown, the external strut members 750 are integrally formed with a turbine blade 40 in accordance with an aspect of the invention, wherein the free ends of the strut members 750 extend from the blade root 42 and are arranged to engage with corresponding nodes 650 of a bearing assembly.

When a turbine blade 40 is connected to the bearing assembly in this manner, the terminal end of the blade root, which generally has an annular form, is spaced apart from the bearing race such that the struts 750 extend across the free space between said blade root and the bearing race. When interconnected in this manner, it is not necessary to introduce a filler material into the space intermediate the blade root and bearing race, however a suitable fairing or covering may be provided to surround and enclose the space in order to shield the struts 750 from the environment.

With reference to Figures 4a and 5, there is shown respective enlarged schematic side and plan views of an exemplary node 600, 650 and strut 700 macrostructure where each node is connected with four other nodes. When a compressive loading P is applied to a node 650, the load is distributed through the node/strut structure as a series of compressive forces (denoted by solid lines) and tensile forces (dashed lines).

As demonstrated by Figure 6, nodes 600, 650 in accordance with the invention can be configured to interconnect with any number n of nodes through the provision of n strut receiving formations 610.

Strut receiving formations 610 are adapted to receive and engage the end of a strut, for example, the free end of an external strut 750. The free end of the strut and the strut receiving formation 610 may be provided with a suitable corresponding mutual engagement means.

Optionally, the mutual engagement means comprises a Hirth coupling.

Optionally, the mutual engagement means is a snap-fit engagement means.

Optionally, the shear pins or clips may be used as an auxiliary connection means.

Optionally, the connections between node and strut are configured to transfer forces through load-bearing surface contacts. Accordingly, the dimensions of the connections are scaled with the cross-sectional area of the strut members in order to transfer the maximum possible stress through the joint.

In figures 7b and 7c there is shown exemplary node 650, 600 and strut 700 lattice structures. It will be appreciated that in these illustrations, the lattice structures are shown having first and second layers A, B of nodes, the nodes of each layer arranged in a ring, however it will be appreciated that a lattice structure can comprise any suitable numbers of layers of nodes, and/or any suitable number of rings of nodes in a layer. Thus it will be appreciated that a lattice structure of interconnected nodes and struts can extend substantially throughout the depth and the width of a bearing race 510, 520 of a bearing assembly in accordance with the embodiments of the invention, and that the nodes of a layer may be connected to any suitable node or nodes of another layer or layers. Thus there is provided the ability to tailor the load bearing capabilities of bearing assemblies in accordance with the present invention.

As the struts 700, 750 and nodes 600, 650 are formed from polymeric materials, said struts can be bonded or fused with a respective node by melting.

Accordingly, external strut members 750 are bondable to the nodes 650 when interconnected to form a continuous blade to bearing interface structure.

For example, in use, struts 700, 750 are introduced into the melted polymeric encasing material 900 and a node at the desired orientation. When the encasing material and/or node is cooled, the strut is thus set in place.

Conveniently, a node or portion of a node, for example in a specific quadrant, can be melted in order to remove and replace a damaged strut without needing to heat and re-melt the whole node.

Advantageously therefore, should a strut or node sustain damage or loss of integrity, said strut and/or node can be replaced or repaired without compromising the integrity of the whole strut / node macrostructure.

In a further aspect of the invention, shown schematically in Figures 8a and 8b, there is provided a bearing assembly 5008 in accordance with the first aspect of the invention configured for use as a yaw bearing. In this configuration the nodes 650 (Figure 8a) of the inner race 510 are adapted for connection to external struts 750 extending from a turbine tower 10, and the outer the outer race 520 is adapted for connection to a turbine nacelle 20, or vice versa.

In a further aspect of the invention, shown schematically in Figure 9, there is provided a bearing assembly 500C in accordance with the first aspect of the invention configured for use as flexible hinge or teetering bearing for a two-blade 40 wind turbine. In this example, the two-bladed rotor attaches to a T-shaped shaft head 36 of a turbine shaft 35 via a hub 30. The cross member of the shaft head may be provided as a separate teeter shaft that is connectable to the shaft head. The hub 30 has an opening 37 to receive the shaft head 36 and opposing openings 38, 39 for teeter bearing assemblies 500 in accordance with the invention located intermediate the hub 30 and the respective opposing horns of the shaft head 36. In this arrangement, the inner bearing race 510 of each bearing assembly 500C engages with a horn of the shaft head 36, with the outer bearing race 520 of each bearing assembly 500 engaging the hub or a blade root, in substantially the same manner as described previously. By tailoring the elastic properties of the node and strut macrostructure, and/or the encasing material of the bearing, for example the polymeric encasing material, the degree of flexure provided by the bearing 500C can be altered. Through use of such bearing assemblies 500C, there is provided a flexible hinge arrangement by which the rotor blade 40 and hub 30 assembly is mountable to a turbine shaft 35. In this way, the two-bladed rotor can tilt or 'teeter' about a limited range of motion about its axis X-X relative to the longitudinal axis of the turbine shaft 35. In this manner, the ability to teeter reduces the stress imparted to the turbine shaft by the blade and hub assembly.

Further advantages of bearing assemblies in accordance with the various aspects of the invention include: -The bearing strut and node macrostructure is very light due to the low density materials used (e.g., fibre reinforced composite struts, nodes). This resultant weight reduction in turn reduces the loads on the turbine nacelle, tower and base, and enables more convenient handling of the bearing assemblies The blade and bearing structures are significantly lighter than prior art blades and bearings. Thus the blades and bearing assemblies offer improved aerodynamic efficiency, thereby maximising energy extraction per unit of time.

-The macrostructure can be robofically assembled aiding precision, cutting down on human error and cost.

-Autoclaves larger than the blade macrostructure are not necessary.

-Turbine blades in accordance with the invention are reusable, unlike existing monolithic blades.

Claims

Claims 1. A bearing assembly for a wind turbine, the bearing assembly comprising an inner race and an outer race; wherein at least one of the inner race or the outer race comprises a plurality of interconnected struts, the struts being interconnected by node members to form a lattice structure.
2. A bearing assembly as claimed in claim 1, wherein a plurality of interconnected struts are provided in the inner race.
3. A bearing assembly as claimed in claim 1 or claim 2, wherein a plurality of interconnected struts are provided in the outer race.
4. A bearing assembly as claimed in any preceding claim, wherein a subset of the node members are adapted to receive external strut members extending from any one or more of a turbine blade, a turbine hub, a turbine tower, a turbine shaft, a turbine shaft head, a turbine teeter shaft.
5. A bearing assembly as claimed in claim 4, wherein each node of the subset is adapted to receive at least one external strut member.
6. A bearing assembly as claimed in claim 4 or claim 5, wherein the nodes of the subset define an upper layer of nodes.
7. A bearing assembly as claimed in any one of claims 4 to 6, wherein the subset nodes and their respective interconnecting struts are at least partially encased in an encasing material.
8. A bearing assembly as claimed in claim 7, wherein the encasing material is a polymeric encasing material.
9. A bearing assembly as claimed in claim 7, wherein the encasing material is a fibre reinforced polymeric encasing material.
10. A bearing assembly as claimed in claim 7, wherein the encasing material is a metal or metal alloy encasing material, wherein the respective nodes and struts are located within suitable node-receiving cavities and strut-receiving channels formed within said metal or metal alloy encasing material.
11. A bearing assembly as claimed in any one of claims 7 to 10, wherein the encasing material is the material from which the bearing race is formed.
12. A bearing assembly as claimed in claim 8 or claim 9, wherein the at least one bearing race comprises a substantially U-shaped annular trough which contains the polymeric encasing material and the lattice structure.
13. A bearing assembly as claimed in claim 12, wherein the substantially U-shaped annular trough is made from metal or metal alloy, and wherein the outer surfaces of the U-shaped annular trough define the bearing race surfaces.
14. A bearing assembly as claimed in claim 12 or claim 13, wherein the polymeric encasing material is introduced into the annular trough in a melted form.
15. A bearing assembly as claimed in any one of claims 7 to 14, wherein one or more of the subset nodes protrude from the encasing material.
16. A bearing assembly as claimed in any one of claims 7 to 15, wherein one or more subset nodes is/are located within the encasing material at one end of an open-end channel extending between the node and the surface of the polymeric encasing material, the channel being configured to receive an external strut member inserted therein.
17. A bearing assembly as claimed in any one of claims 7 to 16, wherein the node members not forming part of the subset of nodes and their respective interconnecting strut members are substantially encased in the encasing material.
18. A bearing assembly as claimed in claim 9 or in any one of claims 12 to 17, wherein the fibre reinforced polymeric encasing material is a thermoplastic.
19. A bearing assembly as claimed in claim 18, wherein the fibre-reinforced thermoplastic is carbon-fibre reinforced polyetheretherketone (PEEK).
20. A bearing assembly as claimed in any one of claims 8, 9 or 12 to 17, wherein the polymeric encasing material is a vitrimer.
21. A bearing assembly as claimed in any preceding claim, wherein the nodes and/or the struts are formed from fiber reinforced polymer, optionally wherein the fiber reinforced polymer is carbon fiber reinforced PEEK.
22. A bearing assembly as claimed in any one claims 1 to 20, wherein the nodes and/or struts are formed from Polyetherimide.
23. A bearing assembly as claimed in any one claims 1 to 20, wherein the struts are formed from any one or more of: carbon fibre reinforced polymer (CFRP), carbon reinforced polymer (CRP), carbon fibre reinforced thermoplastic (CFRTP), glass fibre reinforced polymer (GFRP), Basalt fiber-reinforced polymer (BFRP), or mixtures thereof.
24. A bearing assembly as claimed in any preceding claim, wherein each node is configured to interconnect with any number n of nodes through the provision of n strut receiving formations.
25. A bearing assembly as claimed in claim 24, wherein each strut receiving formations are adapted to receive and engage an end of a strut.
26. A bearing assembly as claimed in claim 25, wherein connected struts and nodes are configured for bonding or fusing by melting.
27. A bearing assembly as claimed in claim 26, wherein subset nodes are reversibly bondable to external struts when interconnected to form a continuous external component-to-bearing interface structure.
28. A bearing assembly as claimed in any one of claims 4 to 27, wherein the bearing assembly is a teeter bearing for a two-blade wind turbine hub, wherein the inner bearing race comprises the subset of nodes adapted to receive external strut members extending from a horn of a turbine shaft head or from a teeter shaft, and wherein the outer bearing race is configured to engage a rotor hub, or a blade root.
29. A bearing assembly as claimed in any one of claims 4 to 27, wherein the bearing assembly is a yaw bearing for a wind turbine, wherein the inner bearing race comprises the subset of nodes adapted for connection to external struts extending from a turbine tower, and wherein and the outer race is adapted for connection to a turbine nacelle.
30. A turbine blade comprising a blade tip, a blade root and a connection means for connecting said blade to a bearing assembly as claimed in any one of claims 1 to 27, wherein the connection means comprises a plurality of struts having a first portion and a second portion, wherein the first portion of each strut is embedded within the blade and wherein the second portion is a free end that projects from the blade root; and wherein the free end of each strut is configured for connection with a corresponding node provided in an race of the bearing assembly.
31. A turbine blade as claimed in claim 30, wherein each strut is integrally formed with the blade.
32. A wind turbine assembly comprising one or more bearing assemblies as claimed in claims 1 to 29.