Variable pitch system for wind turbine blades

Abstract

The present invention relates to a pitch system for a wind turbine blade. The pitch system comprises a blade bearing comprising an inner bearing ring and an outer bearing ring, wherein the outer bearing ring is rotatable relative to the inner bearing ring, and an actuation system configured to control the relative rotational movement between the inner bearing ring and the outer bearing ring. The actuation system comprises a first load transfer beam arrangement spanning at least a first fixed position and a second fixed position associated with the inner bearing ring, a second load transfer beam arrangement spanning at least a first fixed position and a second fixed position associated with the outer bearing ring, and a first linear actuator coupled between the first load transfer beam arrangement and the second load transfer beam arrangement. The pitch system of the present invention has the advantage that it enables a reduction in mass while still maintaining a rigid connection between the hub and the associated blade. Thus, larger and heavier blades can be coupled to the pitch system while mitigating a proportional increase in pitch system mass.

Description

Technical Field

[0001] The present invention generally relates to wind turbines, pitch systems used in such wind turbines, and pitch ring assemblies. Background Technology

[0002] Wind turbines typically consist of a rotor with large blades driven by the wind. The blades convert the kinetic energy of the wind into rotational mechanical energy. Typically, this mechanical energy is transferred via a transmission system to a generator, which then converts the energy into electrical energy.

[0003] Most modern wind turbines control power output by pitching the blades relative to the wind. Therefore, each blade is mounted to the hub via a pitch system that allows for relative rotational movement between the blade and the hub. The pitch system includes a pitch bearing, which typically comprises concentric inner and outer bearing rings. One bearing ring (inner or outer) is attached to the blade, and the other is attached to the hub.

[0004] The pitch system also includes a drive system comprising one or more pitch drive units, such as electric motors or hydraulic or electric linear actuators. The drive units are used to rotate bearing rings attached to the blades relative to bearing rings attached to the hub, thereby adjusting the blade pitch by rotating the blades about their longitudinal axis.

[0005] An example of a pitch system for wind turbine blades is described in the applicant’s earlier PCT application WO2012 / 069062. Figure 1 An exploded perspective view of a prior art pitch system described in WO2012 / 069062 is shown. See also Figure 1 The pitch system 20 includes a bearing 22, a first coupling member 24, a second coupling member 26, and a drive system 28. More specifically, the bearing 22 includes an inner bearing ring 30 mounted to the hub 6 and an outer bearing ring 32 mounted to the blade. The first coupling member 24 is located between the hub 6 and the inner bearing ring 30. The second coupling member 26 is located between the blade and the outer bearing ring 32. The drive system 28 includes a hydraulic actuator 34 connected to the first coupling member 24 and the second coupling member 26, such that the drive system 28 can rotate the inner bearing ring 30 relative to the outer bearing ring 32, thereby pitching the blade relative to the hub 6.

[0006] Figure 1The first connecting member 24 and the second connecting member 26 shown each include a pitch ring for attachment to the respective bearing rings 30, 32. The first connecting member 24 also includes a plate, while the second connecting member 26 includes a crossbeam. The plates and crossbeams of the respective connecting members 24, 26 provide mounting points for the hydraulic actuator 34. In addition to providing mounting points for the actuator 34, one or both of the connecting members 24, 26 may be designed to reduce the load in the bearing rings 30, 32, for example, to ensure that the load is evenly distributed around the circumference of the bearing rings 30, 32. Notably, for example, the plate-shaped first connecting member 24 is generally circular and spans the central region of the inner bearing ring 30 to provide support for the inner bearing ring 30, thereby preventing ellipticization due to forces applied to the inner bearing ring 30 during use. This prevents excessive fatigue loads on the hub casting.

[0007] Over time, the overall size of wind turbine blades has increased significantly due to the desire to capture more usable energy from the wind. For example, the root diameter of existing practical-scale wind turbine blades exceeds 4.5 meters, and this is slated to increase further in the future as blade sizes continue to grow. Larger blades require larger pitch system components, such as bearing rings and actuators, to support the blades and control pitch movement. However, the increase in the size of pitch system components is typically accompanied by a corresponding increase in mass. To reduce the mass of the components, it is desirable to avoid a proportional increase in the mass of the pitch system with the increase in blade size. This invention was designed against this background. Summary of the Invention

[0008] According to one aspect of the invention, a pitch system is provided for rotating the blades of a wind turbine relative to a hub. The pitch system includes: a blade bearing including an inner bearing ring and an outer bearing ring, wherein the outer bearing ring is rotatable relative to the inner bearing ring; and an actuation system configured to control relative rotational motion between the inner and outer bearing rings. The actuation system includes: a first load transfer beam device spanning at least a first fixed position and a second fixed position associated with the inner bearing ring; a second load transfer beam device spanning at least a first fixed position and a second fixed position associated with the outer bearing ring; and a first linear actuator coupled between the first and second load transfer beam devices.

[0009] The advantage of the pitch system of the present invention is that it achieves a reduction in mass while maintaining a rigid connection between the hub and the associated blades. Therefore, larger and heavier blades can be coupled to the pitch system while mitigating a proportional increase in the system's mass.

[0010] In one embodiment, the inner bearing ring is configured to be mounted to the hub, and the outer bearing ring is configured to be mounted to the blade directly or indirectly via an intermediate component. Configuring the pitch system such that the blades are attached to the outer bearing ring offers certain advantages. In principle, for a given blade root diameter typically associated with a given blade length, a radially inward-facing inner bearing ring means that the hub can be manufactured more compactly due to the smaller diameter of the inner bearing ring.

[0011] In one embodiment, when viewed along the rotation axis of the pitch system, a first load transfer beam assembly intersects with a second load transfer beam assembly. The first load transfer beam assembly extends substantially linearly between a first fixed position and a second fixed position. The second load transfer beam assembly also extends substantially linearly between the first fixed position and the second fixed position. In this configuration, the two beam assemblies may appear to intersect or cross each other at the geometric center of the bearing ring. This provides an advantage because a sensor platform can be mounted between the beam assemblies. It is particularly convenient if the sensor platform is constructed in the center, as it can pick up pure rotational motion unaffected by lateral movement between the blades.

[0012] In one embodiment, the first linear actuator has an actuator body mounted to a first load transfer beam assembly and an actuator rod connected to a second load transfer beam assembly. This provides a relatively simple connection between the second load transfer beam assembly and the first linear actuator. To enable the first linear actuator to withstand a degree of elastic deformation between the inner and outer bearing rings, in one embodiment, the first linear actuator can be coupled to one or more of the first and second load transfer beam assemblies via a flexible coupling and optional spherical bearings. This configuration maintains the rigidity of the coupling but allows for flexibility between the actuator and the bearing rings.

[0013] In one embodiment, the first load transfer beam assembly includes a first beam segment and a second beam segment that are parallel to each other. This provides a robust mounting yoke for the actuator, as the actuator can be clamped between the two beam segments.

[0014] Advantageously, the sensor system can be coupled between the first load transfer beam assembly and the second load transfer beam assembly and configured to measure the relative rotational motion between them. This avoids the need for a transducer or encoder system coupled between the inner and outer bearing rings, which is typically a more complex device. Attached Figure Description

[0015] Figure 1 The background art has been described, which shows an exploded perspective view of a prior art pitch system for wind turbines.

[0016] To facilitate a clearer understanding of the invention, embodiments of the invention will now be described by way of non-limiting examples with reference to the remaining drawings, wherein:

[0017] Figure 2 This is a front view of a wind turbine according to the present invention, which includes three blades attached to a central hub via a corresponding pitch system;

[0018] Figure 3 This is a perspective view of a pitch system according to an embodiment of the present invention;

[0019] Figure 4 yes Figure 3 The diagram shows a cross-sectional view of the pitch system.

[0020] Figure 5 yes Figure 3 Another cross-sectional view of the pitch system; and

[0021] Figure 6 This is a schematic diagram of a cross-section of the actuation system, illustrating a possible configuration of the sensor system. Detailed Implementation

[0022] Figure 2 This is a front view of a wind turbine 100 according to the present invention. The wind turbine 100 includes a tower 102, a nacelle 104 located at the top of the tower 102, and a rotor-hub assembly 106 mounted to the nacelle 104. The rotor-hub assembly 106 includes three turbine blades 108 fixed to a central hub 110. The blades 108 are arranged to rotate the rotor-hub assembly 106 when wind strikes the blades 108. The central hub 110 is connected to a main shaft housed in the nacelle 104, which in turn is connected to a power generation system (not shown) also located in the nacelle 104. The central hub 110 rotates the main shaft, and this rotational energy is converted into electrical energy by the power generation system.

[0023] Each wind turbine blade 108 passes through a reference. Figure 1 The pitch system described in the background art is similar to a pitch system mounted on the center hub 6. Therefore, for the overall structure of the pitch system, reference should be made to... Figure 1 Further details of the pitch system can be found in WO2012 / 069062, the contents of which are incorporated herein by reference.

[0024] refer to Figure 3 According to an embodiment of the invention, the pitch system 112 includes a blade bearing assembly or component 114 mounted to a center hub 110. Figure 3 The lower part shows the hub 110, to which the bearing assembly 114 is mounted. It is understood that the blade bearing assembly 114 is just one of many devices mounted on the hub 110; each blade has one blade bearing assembly.

[0025] The blade bearing assembly 114, or more simply, the blade bearing, includes a first bearing ring 120 and a second bearing ring 122 configured to rotate relative to each other. For the purposes of this discussion, the first bearing ring 120 will be referred to as the inner bearing ring, and the second bearing ring 122 will be referred to as the outer bearing ring.

[0026] The inner bearing ring 120 and the outer bearing ring 122 may be arranged between them with conventional rolling elements, such as cylindrical or tapered rollers, in a manner commonly used for this application. The specific form of the rolling elements or equivalent friction-reducing devices between the inner bearing ring 120 and the outer bearing ring 122 is not critical to the invention and therefore will not be discussed further here. The inner bearing ring 120 and the outer bearing ring 122 are oriented about the axis of rotation X, and thus define the axis of rotation X for the blade bearing, which in... Figure 3 It is shown as extending vertically upwards along the page.

[0027] In the illustrated embodiment, the inner bearing ring 120 is secured to the hub 110 by suitable fasteners (such as bolts), thus it is rotatably coupled to the hub 110. Note that although a ring of bolt holes 123 is shown in the figure, these fasteners are not shown. Typically, the inner bearing ring 120 will be a separate part of the hub 110 and securely fixed to it, as this provides greater ease of manufacture. However, the inner bearing ring 120 can also be an integral part of the hub 110, allowing it to be cast and / or machined from the same piece of material (e.g., cast steel).

[0028] In the illustrated embodiment, the outer bearing ring 122 rotates relative to the inner bearing ring 120 and is therefore adapted to connect to the blade, such that the rotational position of the outer bearing ring 122 can control the blade pitch angle. Figure 3 In this design, the outer bearing ring 122 defines a ring of bolt holes 124 around its circumferential edge. The bolt holes 124 serve as fixing points for the blades, as understood by those skilled in the art. The blades and associated fasteners are not shown here. Advantageously, since the outer bearing ring 122 is fixed to the blades in use, this means that for a given blade root diameter, the inner bearing ring 120 has a smaller diameter, which in turn means that the hub can be more compact.

[0029] The pitch system 112 includes an actuation system 130 that controls the relative movement between the inner bearing ring 120 and the outer bearing ring 122. As can be seen in WO2012 / 069062, a challenge of conventional actuation systems is providing a sufficiently rigid connection between the inner and outer bearing rings. A rigid connection is important because it resists torsional loads exerted by the blades, for example, during gusts, which attempt to rotate the blade bearings and may cause pitch errors. A less rigid connection may occur due to excessive elastic deformation of components involved in the load path between the inner and outer blade bearings and the actuation components of the pitch system.

[0030] The pitch system 112 of the present invention provides an advantageous rigid connection, which results in more precise pitch actuation and reduced bearing wear. The pitch system 112 of the present invention also achieves a reduction in mass compared to conventional methods because it enables the use of a simplified design, avoiding the use of large and expensive cast iron hubs as in conventional designs, such as WO2012 / 069062.

[0031] Back Figure 3 The actuation system 130 includes a first load transfer beam assembly 132 and a second load transfer beam assembly 134, which together provide a rotatably driven connection between the inner bearing ring 120 and the outer bearing ring 122. Figure 3 As shown, in this embodiment, the first load transfer beam device 132 is generally linear and spans between a first fixed position 136 and a second fixed position 138 on the inner bearing ring 120. In this embodiment, the two fixed positions 136 and 138 are separate and radially opposite each other.

[0032] Similar to the first load transfer beam device 132, the second load transfer beam device 134 is also generally linear and spans between a first fixed position 140 and a second fixed position 142 on the outer bearing ring 122. In the illustrated embodiment, these two fixed positions 140, 142 of the second load transfer beam device 134 are also separate and radially opposite.

[0033] In the illustrated embodiment, the actuation system 130 includes a pair of linear actuators 146 coupled between a first load transfer beam assembly 132 and a second load transfer beam assembly 134, and arranged to generate an angular force on the second load transfer beam assembly 134 during operation. Thus, the outer bearing ring 122 is controlled to rotate relative to the inner bearing ring 120. It should be noted that a pair of linear actuators 146 is provided because this generates a more uniformly distributed force on the outer bearing ring 122. Furthermore, this means that a smaller actuator can be used instead of a single actuator with a larger load capacity. The linear actuator can be implemented as a pneumatic or electrically driven linear actuator, such as a lead screw-based linear actuator, but for high-load applications, a hydraulic actuator is more suitable.

[0034] Each of the first load transfer beam device 132 and the second load transfer beam device 134 includes a corresponding mounting bracket, which is connected between the inner bearing ring 120 and the outer bearing ring 122, respectively.

[0035] More specifically, the first load-transfer beam assembly 132 includes a first mounting bracket 150, a second mounting bracket 152, and a beam or support 154 connected to and extending between the first and second mounting brackets 150 and 152. The beam 154 is shown here as a composite beam and therefore comprises a pair of beam segments 154a and 154b, although a single beam segment is also acceptable. However, the double-beam arrangement has certain load-sharing advantages, which will become apparent in the discussion below.

[0036] As shown in the figure, the mounting brackets 150 and 152 of the first load transfer beam device 132 are used to connect the corresponding ends of a pair of beam segments 154a and 154b to the inner bearing ring 120. Although in Figure 3 Two mounting brackets, 150 and 152, are shown, but... Figure 5 The diagram shows a cross-sectional view through one of the mounting brackets 150. It can be understood that the mounting bracket 150 is generally annular and includes a bracket base 156 and two arms 158 that converge at the apex of a connecting portion 160 defining the mounting bracket 150. Thus, the bracket base 156 and arms 158 provide a generally annular (more specifically triangular) bracket that defines a central region / hole 162 of the opening. Here, the central hole is relatively large to define the relatively slender bracket base 156 and arms 158. The construction of the bracket 150 provides it with a degree of flexibility, particularly in the radial direction. This flexibility allows for some separation between the ellipticization of the inner bearing ring 120 and the beam segments 154a, 154b, which reduces material fatigue while maintaining acceptable stiffness for effective actuation of the linear actuator.

[0037] Mounting bracket 150 connects to beam segments 154a, 154b at its connecting portion 160, where a bearing housing 163 is formed. Bearing housing 163 is defined by a bore 164 that accommodates a spherical bearing 166, which is connected to a mounting mandrel or pin 168. Mounting pin 168 extends through the spherical bearing 166 and is secured at each of its ends 168a, 168b to the ends of the corresponding beam segments 154a, 154b. Thus, when the actuator drives the outer bearing ring 122, the arrangement of the spherical bearing 166 provides beam 154 with the ability to adapt to geometric changes. Therefore, bearing housing 163 in this configuration provides at least two degrees of freedom, including at least one rotational degree of freedom, which allows beam segments 154a, 154b to rotate and tilt relative to mounting bracket 150.

[0038] Note that the second mounting bracket 152 has the same structure as the first mounting bracket 150 in the illustrated embodiment, therefore, for the sake of brevity, no further description will be provided.

[0039] As shown in the figure, beam 154 of the first load transfer beam assembly 132 provides mounting points for the pair of linear actuators 146. In this example, the linear actuator 146 is hydraulic and includes an actuator body 170 and an actuator rod 172, which can slide within a cylinder (not shown) conventionally defined in the actuator body 170. Here, the actuator body 170 is connected to beam 154, and the actuator rod 172 is connected to the second load transfer beam assembly 134.

[0040] See details Figure 4 and Figure 5 The connection between beam 154 and one of the actuators 146 is clearly visible. It can be seen that the actuator body 170 is surrounded by these two beam segments 154a and 154b. These two beam segments effectively act as a flexible yoke-type connector for the actuator body 170, which is supported by beam segments 154a and 154b, allowing the actuator body 170 to move at an angle in a direction approximately perpendicular to the rotational axis X of the blade bearing. Any suitable bearing can be used to rotatably support the actuator body 170. Figure 4 and Figure 5 As can be seen in the figure, the actuator body 170 includes a pair of opposing mounting lugs 174, which are vertically oriented in the figure and are received in corresponding sockets 176 defined in beam segments 154a, 154b. Therefore, this mounting configuration allows the actuator body 170 to laterally swing in a plane parallel to the plane defined by the blade bearing with a first degree of freedom (rotational degree of freedom), thus providing a flexible connection. The interface between the socket 176 and the mounting lugs 174 can also be implemented as a bearing providing multiple degrees of freedom, such as a spherical bearing or a universal joint device.

[0041] The advantage of the first load-transfer beam assembly 132 is that it provides radial stiffness between its radially opposed mounting brackets 150, 152, thereby resisting the ellipticization of the corresponding inner bearing ring 120, while possessing beneficial torsional flexibility due to the ability of beam 154 to torsion about its longitudinal axis. In use, the inner bearing ring 120 and outer bearing ring 122 deform slightly due to the loads they receive from the blades. This means that actuators 146 can be pulled out and misaligned with the bearing plane, but they must still be able to function by applying pitch loads to the bearing. The torsional flexibility of beam 154 means that the two actuators can be moved out of the plane independently of each other while still functioning to apply forces to the outer bearing ring 122. The parallel beam arrangement of a pair of beam segments 154a, 154b shown in the figure provides a refined and simple implementation of torsional flexibility, although this parallel beam arrangement remains relatively rigid to in-plane moments (e.g., bending and radial forces) and provides a robust yoke-like mounting for the actuators. In the illustrated embodiment, beam 154 includes at least one beam member or segment extending along a longitudinal axis, and this beam member or segment is longer in this axial direction than in its width and thickness directions transverse to the longitudinal axis of the beam. However, other configurations are still possible. For example, a tubular beam would provide high stiffness against bending and radial forces and could be configured with a swivel bearing at a point along its length to provide torsional flexibility. However, this configuration would be more complex due to the need for additional swivel bearings. Theoretically, a similar result could be achieved with a beam having a box-shaped or tubular cross-sectional profile, but the walls of such a beam would need to be constructed with suitable forming elements, such as slots and holes, to impart the desired flexibility. Again, such a configuration would have increased complexity compared to the refined form of the illustrated embodiment.

[0042] Turning to the second load transfer beam assembly 134, this component also includes a first mounting bracket 180 and a second mounting bracket 182, and a beam or support 184 connecting them. However, in this case, both mounting brackets 180, 182 are connected to the outer bearing ring 122. Since the beam 184 is linear, in the illustrated embodiment, the first mounting bracket 180 and the second mounting bracket 182 of the second load transfer beam assembly 134 are positioned approximately radially opposite each other. It should be noted that the beam 184 can be a single beam, or it can comprise a pair of beam segments, as in... Figure 5 As can be seen particularly clearly, this makes it easier to install on its corresponding mounting bracket.

[0043] As shown in the figure, the outer bearing ring 122 has a higher configuration than the inner bearing ring 120, such that the axial end face of the outer bearing ring 122 is spaced apart from the axial end face of the inner bearing ring 120. This comparative configuration prevents possible collision between the bolts (not shown) on the inner bearing ring and the lower side of the second load transfer beam assembly when the second load transfer beam assembly rotates.

[0044] Specifically, due to the linear construction of the first load transfer beam assembly 132 and the second load transfer beam assembly 134 (where each of them extends between radially relative positions on the inner and outer bearing rings, respectively), it should be understood that, when viewed along the rotation axis X of the pitch system 112, beam 184 of the second load transfer beam assembly 134 intersects with the first load transfer beam assembly 132. More specifically, the two beams 154, 184 intersect at a point substantially coinciding with the geometric center of the blade bearing (as indicated by the rotation axis X).

[0045] The composite structure of beam segments 154a and 154b of the first load transfer beam device 132 is particularly advantageous here because the beam 184 of the second load transfer beam device 134 can pass through the space between the parallel beam segments 154a and 154b.

[0046] The mounting brackets 180 and 182 of the second load transfer beam device 134 are in Figure 3 It is shown in, but also in Figure 4 and Figure 5 The details are shown below. Each mounting bracket 180, 182 is identical in form, therefore reference will be made to... Figure 4 and Figure 5 Only one of them will be described in detail.

[0047] The first mounting bracket 180 is plate-shaped and provides an interface for bridging between the beam 184 and the outer bearing ring 122. The first mounting bracket 180 has a base portion 186 and an intermediate tapered portion. The base portion 186 is connected to the outer bearing ring 122 at a series of bolted connection points. The intermediate tapered portion terminates at a connecting tongue 190, which is secured to the end of the beam 184. As shown here, the connection between the connecting tongue 190 and the beam 184 is achieved by an array of bolts 192; however, as those skilled in the art will understand, other connection methods are also acceptable.

[0048] As can be understood from the figure, the first mounting bracket 180 is fixed to the outer bearing ring 122 in such a way that the outer bearing ring 122 maintains a flat and uniform contact surface for attachment to the blade. For this purpose, the outer bearing ring 122 is shaped to define first and second cut or "recessed" portions 194 (in... Figure 4(Best shown in the diagram), the first and second cut or "recessed" portions 194 are shaped to mate with the corresponding base portions 186 of the mounting brackets 180, 182. The depth of the cut portion 194 matches the thickness of the corresponding mounting bracket 180, 182. As a result, the upper surfaces of the mounting brackets 180, 182 (particularly their base portions 186) are substantially flush with the adjacent surfaces of the outer bearing ring 122. Thus, the axial facing surfaces of the outer bearing ring 122 and the mounting brackets 180, 182 together provide a flat surface against which the adjacent mating surfaces of the blades can be secured. It should be noted that the recessed portion 194 should be considered optional. In an alternative embodiment, the outer bearing ring 122 is not provided with a recessed portion, but instead is provided with an intermediate member to provide an interface between the axial end face of the outer bearing ring and the root end of the blade. This interface member will be suitably shaped to accommodate the protruding mounting bracket of the second load transfer beam assembly.

[0049] Given that the first load transfer beam assembly 132 is connected to the body of the linear actuator 146, the second load transfer beam assembly 134 is connected to the actuator rod 172. More specifically, the actuator rod 172 of each linear actuator 146 is connected to a corresponding mounting bracket in the mounting brackets 180, 182, and... Figure 4 and Figure 5 The connections between these components are clearly visible. Although not shown in the figure, it should be noted that the actuator rod 172 is connected to the corresponding mounting brackets 180, 182 via suitable couplings that provide at least one rotational degree of freedom of movement, for example, allowing the actuator rod to oscillate at an angle within the plane of the mounting brackets when the inner bearing ring 120 and the outer bearing ring 122 rotate relative to each other. More complex bearing arrangements (e.g., spherical bearings) can be provided to provide more than one degree of freedom of movement.

[0050] from Figure 3 It can be particularly clear that the construction of the first load transfer beam device 132 and the second load transfer beam device 134, and their connection with the linear actuator 146, implies that the linear actuator 146 is oriented in a parallel relationship. This is advantageous because when the two actuators 146 are operating, they apply a force to the outer bearing ring 122, which is balanced on opposite sides of the outer bearing ring 122. Using two linear actuators is advantageous for various reasons. For example, in the case of hydraulic actuators, using two actuators means that the actuators can have a simpler design and more versatile components. Furthermore, the two actuators can be connected to a common hydraulic source, which ensures that each actuator applies the same force.

[0051] In a supplement to the illustrated embodiment, the actuation system 130 of the present invention may be equipped with a suitable sensor system. Figures 3 to 5(Not shown in the image) to measure the degree of relative movement between the first load transfer beam device 132 and the second load transfer beam device 134. Figure 6 The diagram schematically illustrates one way to achieve this, wherein a rotary transducer 210 is coupled between beam 154 of the first load transfer beam assembly 132 and beam 184 of the second load transfer beam assembly 134. The rotary transducer 210 can be coupled between these two beams 154, 184, as shown here, such that the rotary input end is attached to the upper beam segment 154a and aligned with the rotation axis X of the pitch system. This will provide a suitable position because the rotary transducer 210 will undergo relative rotation between beams 154, 184, rather than relative translation. This arrangement will be advantageous because it will avoid the more complex transducer / encoder system mounted between the inner and outer bearing rings.

[0052] Those skilled in the art will understand that the illustrated embodiments are one example of how the invention is implemented. Therefore, the embodiments described herein are provided for illustrative purposes only and should not be construed as limiting the scope of the invention. Some variations of the illustrated embodiments have been described above, but those skilled in the art will understand that other variations are possible without departing from the invention as defined by the claims.

Claims

1. A pitch system (112) for rotating the blades of a wind turbine relative to a hub (110), the pitch system comprising: A blade bearing comprising an inner bearing ring (120) and an outer bearing ring (122), wherein the outer bearing ring is rotatable relative to the inner bearing ring; Actuation system (130) configured to control relative rotational motion between the inner bearing ring and the outer bearing ring, the actuation system comprising: A first load transfer beam device (132) spans at least a first fixed position and a second fixed position associated with the inner bearing ring; A second load transfer beam device (134) spans at least a first fixed position and a second fixed position associated with the outer bearing ring; and A first linear actuator (146) is connected between the first load transfer beam device and the second load transfer beam device. The first load transfer beam device (132) is connected to the inner bearing ring (120) via corresponding first mounting brackets (150) and second mounting brackets (152) at the first fixed position and the second fixed position associated with the inner bearing ring (120). The first load transfer beam device (132) is connected to at least one of the first mounting bracket (150) and the second mounting bracket (152) via a corresponding beam connector having at least a rotational degree of freedom.

2. The pitch system according to claim 1, wherein, The inner bearing ring (120) is configured to be mounted to the hub (110).

3. The pitch system according to claim 1 or 2, wherein, The outer bearing ring (122) is configured to be mounted on the blade.

4. The pitch system according to claim 1 or 2, wherein, When viewed along the rotation axis (X) of the pitch system (112), the first load transfer beam device (132) intersects with the second load transfer beam device (134).

5. The pitch system according to claim 1 or 2, wherein, The first load transfer beam device (132) extends linearly between the first fixed position and the second fixed position associated with the inner bearing ring.

6. The pitch system according to claim 1 or 2, wherein, The second load transfer beam device (134) extends linearly between the first fixed position and the second fixed position associated with the outer bearing ring.

7. The pitch system according to claim 1 or 2, wherein, The first fixed position and the second fixed position associated with the outer bearing ring (122) are radially opposite to each other, and / or the first fixed position and the second fixed position associated with the inner bearing ring (120) are radially opposite to each other.

8. The pitch system according to claim 1 or 2, wherein, The first linear actuator (146) has an actuator body (170) mounted to the first load transfer beam device (132) and an actuator rod (172) connected to the second load transfer beam device (134).

9. The pitch system according to claim 8, wherein, The actuator body (170) is connected to the first load transfer beam device (132) via a connector having at least a rotational degree of freedom.

10. The pitch system according to claim 8, wherein, The actuator rod (172) is connected to the second load transfer beam device (134) via a connector having at least a rotational degree of freedom.

11. The pitch system according to claim 1, wherein, At least one of the first mounting bracket (150) and the second mounting bracket (152) defines the central region of an opening.

12. The pitch system according to claim 11, wherein, At least one of the first mounting bracket (150) and the second mounting bracket (152) has a bracket base (156) and a pair of converging arms (158), the bracket base being connected to the inner bearing ring (120) and the arms being connected to the beam (154) of the first load transfer beam device (132).

13. The pitch system according to claim 1 or 2, wherein, The first load transfer beam device (132) includes a first beam segment (154a) and a second beam segment (154b).

14. The pitch system according to claim 13, wherein, The first beam segment (154a) and the second beam segment (154b) are parallel to each other.

15. The pitch system according to claim 14, wherein, The second load transfer beam device (134) extends between the first beam segment (154a) and the second beam segment (154b).

16. The pitch system according to claim 14, wherein, The first linear actuator (146) is positioned between the first beam segment (154a) and the second beam segment (154b).

17. The pitch system according to claim 1 or 2, further comprising a sensor system (210) coupled between the first load transfer beam device (132) and the second load transfer beam device (134) and configured to measure the relative rotational motion between the first load transfer beam device (132) and the second load transfer beam device (134).

18. The pitch system according to claim 1 or 2, the pitch system further comprising a second linear actuator (146) connected between the first load transfer beam device (132) and the second load transfer beam device (134).

19. The pitch system according to claim 18, wherein, The first linear actuator (146) and the second linear actuator (146) are connected between the first load transfer beam device (132) and the second load transfer beam device (134) so ​​that they extend parallel to each other.

20. A pitch system (112) for rotating the blades of a wind turbine relative to a hub (110), the pitch system comprising: A blade bearing comprising an inner bearing ring (120) and an outer bearing ring (122), wherein the outer bearing ring is rotatable relative to the inner bearing ring; Actuation system (130) configured to control relative rotational motion between the inner bearing ring and the outer bearing ring, the actuation system comprising: A first load transfer beam device (132) spans at least a first fixed position and a second fixed position associated with the inner bearing ring; A second load transfer beam device (134) spans at least a first fixed position and a second fixed position associated with the outer bearing ring; and A first linear actuator (146) is connected between the first load transfer beam device and the second load transfer beam device. The second load transfer beam device (134) is connected to the outer bearing ring (122) via a corresponding first mounting bracket (180) and a second mounting bracket (182) at the first fixed position and the second fixed position associated with the outer bearing ring (122). The outer bearing ring (122) defines a recessed portion (194) that mates with the base portion (186) of the corresponding first mounting bracket (180) or second mounting bracket (182), such that the upper surface of the base portion is flush with the adjacent surface of the outer bearing ring.

21. A pitch system (112) for rotating the blades of a wind turbine relative to a hub (110), the pitch system comprising: A blade bearing comprising an inner bearing ring (120) and an outer bearing ring (122), wherein the outer bearing ring is rotatable relative to the inner bearing ring; Actuation system (130) configured to control relative rotational motion between the inner bearing ring and the outer bearing ring, the actuation system comprising: A first load transfer beam device (132) spans at least a first fixed position and a second fixed position associated with the inner bearing ring; A second load transfer beam device (134) spans at least a first fixed position and a second fixed position associated with the outer bearing ring; and A first linear actuator (146) is connected between the first load transfer beam device and the second load transfer beam device. The first load transfer beam device (132) includes a first beam segment (154a) and a second beam segment (154b). The second load transfer beam device (134) extends between the first beam segment (154a) and the second beam segment (154b).

22. A pitch system (112) for rotating the blades of a wind turbine relative to a hub (110), the pitch system comprising: A blade bearing comprising an inner bearing ring (120) and an outer bearing ring (122), wherein the outer bearing ring is rotatable relative to the inner bearing ring; Actuation system (130) configured to control relative rotational motion between the inner bearing ring and the outer bearing ring, the actuation system comprising: A first load transfer beam device (132) spans at least a first fixed position and a second fixed position associated with the inner bearing ring; A second load transfer beam device (134) spans at least a first fixed position and a second fixed position associated with the outer bearing ring; and A first linear actuator (146) is connected between the first load transfer beam device and the second load transfer beam device. The first load transfer beam device (132) includes a first beam segment (154a) and a second beam segment (154b). The first linear actuator (146) is positioned between the first beam segment (154a) and the second beam segment (154b).

23. A pitch system (112) for rotating the blades of a wind turbine relative to a hub (110), the pitch system comprising: A blade bearing comprising an inner bearing ring (120) and an outer bearing ring (122), wherein the outer bearing ring is rotatable relative to the inner bearing ring; Actuation system (130) configured to control relative rotational motion between the inner bearing ring and the outer bearing ring, the actuation system comprising: A first load transfer beam device (132) spans at least a first fixed position and a second fixed position associated with the inner bearing ring; A second load transfer beam device (134) spans at least a first fixed position and a second fixed position associated with the outer bearing ring; and A first linear actuator (146) is connected between the first load transfer beam device and the second load transfer beam device. The first load transfer beam device (132) is connected to the inner bearing ring (120) via corresponding first mounting brackets (150) and second mounting brackets (152) at the first fixed position and the second fixed position associated with the inner bearing ring (120). The first load transfer beam device (132) is connected to at least one of the first mounting bracket (150) and the second mounting bracket (152) via a corresponding beam connector having rotational degrees of freedom about a longitudinal axis between the first fixed position and the second fixed position associated with the inner bearing ring.

24. The pitch system according to claim 23, wherein, The second load transfer beam device (134) is connected to the outer bearing ring (122) at the first fixed position and the second fixed position associated with the outer bearing ring (122) via corresponding first mounting bracket (180) and second mounting bracket (182), wherein the outer bearing ring (122) defines a recessed portion (194) that mates with the base portion (186) of the corresponding first mounting bracket (180) or second mounting bracket (182) such that the upper surface of the base portion is flush with the adjacent surface of the outer bearing ring.

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