Elastic rotary bearing for two-blade rotor of wind power plant

Abstract

The invention relates to a rotary bearing for a two-blade rotor which is recycled for high loads in a wind power plant. The invention relates in particular to a novel rotor hub for a two-blade rotor, in particular a resiliently supported, of a wind turbine, into which a resilient rotary bearing is integrated, which in turn consists of two rotary joint units consisting of layered elements and conical elements.

Description

Technical Field

[0001] The invention relates to an elastic rotation bearing for a two-blade rotor which is suitable for high load cycles (Lastzyklen, sometimes referred to as load cycles) and is used in a wind power plant.

[0002] In particular, the invention relates to a novel rotor hub for a sprung-mounted two-blade rotor of a wind turbine, wherein an elastic rotational bearing for the rotor is integrated into the rotor hub.

[0003] In particular, the invention relates to a corresponding rotor hub which is designed in such a way that the rotational elastic elements and the axial elastic elements are arranged in a small space in such a way that when high axial and radial forces act simultaneously on the rotor blades during operation, a reversible pendulum-like movement can occur in the structural direction of the wind turbine. Background Art

[0004] Most wind turbines installed and erected today have three rotor blades that are evenly distributed in one plane, so that a load that is as uniform as possible occurs in each revolution.

[0005] In contrast, two-blade rotors are an exception since they generate greater switching loads.

[0006] However, especially in offshore applications, two-blade rotors offer the following advantages:

[0007] ● Lower cost due to fewer rotor blades;

[0008] Simple transportation, since several rotors can be stored in parallel on a transport ship, whereas a three-blade rotor requires a very large area in the assembled state. Therefore, the rotor blades must be assembled individually, which means a considerable expenditure of time;

[0009] • Simple assembly, since the assembled rotor can be lifted like a horizontal "beam".

[0010] In contrast, a major disadvantage of a two-blade rotor is the uneven loading during each revolution of the rotor.

[0011] In a rotor blade that is in a vertical position, the vertical shear wind (Scherwind, sometimes called wind shear) causes a pitching motion, while the horizontal shear wind has no effect or only a small effect.

[0012] In horizontal rotor blades, the horizontally different shear winds lead to loads in the yaw direction. At the same time, the mass moment of inertia of the rotor and thus of the entire device changes permanently during each revolution.

[0013] These continuous load and inertia changes place significant loads on all components following the rotor, such as the rotor hub, rotor shaft, rotor bearings, transmission, generator and tower.

[0014] The influence of the tower wake also leads to greater loads than is the case with three-blade rotors.

[0015] In order to prevent these loads, it is sensible to support the rotor in a pendulum-like manner so that the rotor no longer transmits pitch and yaw forces. Ideally, therefore, only the desired torsional forces should still be transmitted for driving the generator.

[0016] To this end, it has hitherto been proposed to use circular elastic bearing elements which enable a pendulum-like movement of the rotor.

[0017] A known example is realized in the MOD-2 two-blade wind turbine (Institute for Solar Energy Research, 1980, SERI / SP 738-728): the circular layered element (Schichtelement, sometimes called stacked element) is arranged here in such a way that it absorbs essentially only radial forces. However, in order to transmit radial loads, the circularly arranged elements require a large diameter, which increases with the size of the device due to higher loads and weight. The shearing movements that occur in the elastomer layer become larger when the same angular movement is carried out on the required larger diameter, so that the shearing movements can no longer be absorbed by the elastomer element with reasonable effort. From the cited description and the drawings associated therewith, it is not clear whether the mentioned elastic layered element of the MOD-2 device is designed in such a way that it can also transmit larger axial forces. In addition, the circular layered element appears to have a large diameter and therefore requires a significant space requirement in the rotor hub.

[0018] WO 2012 / 076892 discloses a swing bearing for a rotor of a wind turbine, which is not described in detail in terms of construction, using cylindrical and conical elastic stop elements. The swing bearing can achieve a swing angle of +20° to -20° and is arranged in such a way that axial forces can only be transmitted slightly.

[0019] Elastic bearings that can absorb radial as well as axial forces are also known in the prior art, but are used for other technical tasks. Thus, for example, WO 2010 / 054808 describes a machine or transmission bearing that is a combination of an elastic sandwich bearing and an elastic conical bearing, wherein a plurality of such bearings, for example, produce a circumferential elastic connection between the rotor shaft of a wind turbine and the machine support. The cone elements used are designed to be relatively flat and therefore have a relatively wide cone angle of up to 50°, since the cone elements must also transmit high axial forces. The cone and the sandwich element are arranged here in such a way that, corresponding to the task to be solved, they cannot transmit torsional forces and therefore also cannot transmit rotation angles, such as a pendulum-like movement of the rotor.

[0020] The object is therefore to provide an elastic bearing for a two-blade rotor which allows reversible torsional movements and rotation angles of the rotor blades with the smallest possible diameter or with the smallest possible space requirement in the rotor hub and which is capable of absorbing radial and axial loads in order to keep deformations that are dependent on the diameter and the rotation angle as small as possible. The weight load of a two-blade rotor weighing 100-300 t results in varying loads in the axial direction of the bearing with each revolution of the rotor. In particular, offshore installations must be maintenance-free over their entire service life of at least 30 years. Due to the fact that the elastomeric components are provided with a diameter of approximately 1.510 mm, the bearings are subjected to a large amount of stress. The ... 8 The axial load cycles required during the service life of the sub-cycle are very high, so only small deformations in the axial direction are permitted in the elastomer. These deformations cannot be transmitted by a tapered bearing optimized for optimal rotational deformation.

[0021] Likewise, the rotor performs a continuous pendulum-like motion in order to compensate for the pitch and yaw loads, so that here, torsional loads also occur in very large cycles. As a result, the tapered bearings must be designed for large load cycles. This requires the smallest possible diameter and a small cone angle, which is not suitable for transmitting axial forces. In order to transmit axial forces with small elastomer deformations, the diameter and cone angle must be large, which in turn is not conducive to high torsional loads.

[0022] This object is achieved by a rotary bearing or a rotor hub as described in detail below and in the claims. Summary of the invention

[0023] The subject matter of the invention is therefore an elastic bearing for a rotor hub with high load cycles for an elastically supported two-blade rotor of a wind turbine, or a rotor hub with an elastic bearing, wherein the rotor is able to perform a pendulum-like movement around a rotation angle of at least 3° when simultaneously high axial and radial forces act.

[0024] The rotating bearing according to the invention, which is a component of a novel rotor hub, comprises a first inner component, which is firmly connected to the rotor shaft and therefore to the structure of the wind turbine, and a second outer movable component, which has a connection area for two oppositely arranged rotor blades, wherein the first firmly connected inner component and the second movable outer component are connected to each other by means of two oppositely arranged rotary joint units that can absorb torsional forces in such a way that the rotor blades connected to the rotor hub can be reversibly moved in the direction of the rotating structure of the wind turbine or away from the rotating structure when a force acts on it.

[0025] According to the invention, the rotor hub comprises two rotary joint units according to the invention, which are arranged opposite each other in the rotor hub and are firmly connected to each other. Each of the two rotary joint units is essentially constructed from:

[0026] (a) at least one conical bushing, each comprising a plurality of, preferably six to ten, elastic layers, for absorbing forces acting predominantly radially relative to the cone axis, said conical bushing having a cone angle which is as small as possible, for example not more than 15°, preferably less than 10°, due to the small available space requirement, and

[0027] (b) At least one, preferably two, preferably four to eight layers of elastic layered spring (Schichtfeder, sometimes called stacked spring), which is arranged in such a way that it has a common axis with the tapered bushing and absorbs axially acting forces that cannot be absorbed by the tapered bushing.

[0028] In both conical elements and lamellar spring elements, the elastic layers are connected to one another by inelastic fixing layers (for example sheet metal).

[0029] In order to be able to install the first inner component into the second outer movable component, the outer dimensions of the inner component must be kept small. For this purpose, in one embodiment according to the invention, the conical bushing can be designed to be removable. The bending moment is transmitted here by means of a central screw or a plurality of screws arranged in a circle. The radial force transmission is achieved by means of an annular releasable guide (groove element) and a correspondingly shaped conical element.

[0030] The connector unit according to the invention is designed such that

[0031] a first inner fixing component, for example in the form of a carrier plate, which is firmly connected at two opposite sides to the innermost layer of the respective conical bushing, wherein the cone axis is arranged perpendicular to the axis of the rotor shaft, and

[0032] The second outer movable component is firmly connected to the outermost layer of the respective conical bushing, so that under the action of force, a reversible torsional deformation of the respective elastic layer of the conical bushing and, if applicable, an axial / radial deformation of the respective lamellar spring occurs. This allows the aforementioned pendulum-like movement of the double-blade rotor to be achieved.

[0033] The rotor hub with the rotary bearing according to the invention usually has two oppositely disposed rotary joint units. The two conical elements and the two layered spring elements are preferably arranged along the same axis, wherein at least one layered spring element belongs to each of the two conical elements, each of the conical elements forming a structural unit with the layered spring element. The conical layered spring units are preferably firmly connected to a rigid, immovable component (e.g. a carrier plate) via connecting elements (e.g. a bolt-like part or a pin-like part whose end is formed corresponding to the conical bushing). In this case, the two oppositely disposed conical bushings are clamped together so strongly that the residual preload is maintained in any state even in the case of changing loads due to the rotor weight of the double-blade rotor.

[0034] According to the invention, the lamellar spring, which is to transmit mainly axial forces, can be designed as a flat sandwich element or a hemispherical element. In the radial direction, the flat lamellar spring is very soft and thus does not transmit significant (nennenswert, sometimes referred to as considerable) radial loads. The radial loads are completely absorbed by the conical bushing, which is significantly more rigid in the radial direction. As a result, the cone angle (defined above and below as half the cone angle) and therefore also the torsional movements in the elastomeric element can be kept small, in particular between 5 and 15°.

[0035] In contrast, the semiconical element is not completely so soft and can also transmit axial forces to a certain extent. In another embodiment of the invention, the flat sandwich element of the conical layered spring unit is replaced by two oppositely arranged, preferably mutually connected hemispherical elements. The hemispherical elements are very rigid in the axial direction and have a small diameter, so that large rotation angles can be achieved with a small number of layers. Therefore, radial movement can be achieved by universal deformation of two hemispherical elements that are separated from each other by the rotation point distance.

[0036] Surprisingly, it has been found that the rotary bearing according to the invention can be optimized with regard to its effect on radial and torsional deformations if the layer thicknesses, layer lengths and the stiffness or Shore hardness of the material are varied in a targeted manner.

[0037] The subject of the invention is therefore a corresponding rotary bearing for a double-bladed rotor, wherein the outer elastic layer of the conical bushing has a lower Shore hardness than the inner elastic layer. Preferably, the Shore hardness increases continuously from the outside to the inside, for example by 2-5% per layer.

[0038] Furthermore, a rotation bearing is particularly advantageous in which the inner elastic layer of the conical bushing has a greater thickness than the outer elastic layer. Preferably, the thickness of the elastic layer decreases continuously from the inside to the outside, for example by 5-10% per layer.

[0039] Furthermore, it has been found that it is also advantageous in view of the limited space conditions in the rotor hub if the outer layers of the tapered bushing are shorter than the inner layers, wherein shortening by three or four outer layers is sufficient.

[0040] Therefore, in one embodiment of the invention, the outer layer of the tapered bushing is shorter than the inner layer and has a lower stiffness or Shore hardness than the longer inner layer with a higher stiffness.

[0041] In another embodiment of the present invention, the outer layer of the tapered bushing is shorter than the inner layer and has a smaller thickness than the inner layer.

[0042] Another embodiment of the invention combines a shorter, thinner and softer outer layer of the tapered bushing with a longer, thicker and harder inner elastic layer. Such a tapered bushing is optimized with respect to its radial and torsional deformation when forces act on the rotary bearing according to the invention.

[0043] The rotary bearing according to the invention is designed in such a way that at least in strong pendulum-like movements the movable part of the rotor hub can strike the fixed part. In order to avoid damage and undesired recoil effects, it is expedient according to the invention to provide a stop device, for example in the form of an elastic damper.

[0044] This is important for rotation angles due to external influences such as extreme wind gusts ( In the case of excessively large angles (sometimes called gusts) or also adjustment errors (e.g. > 4°), it is meaningful. For example, the stop can be arranged between the fixed component and the movable component of the rotating bearing or the rotor hub. In the case of excessive angles, the stop can then have the task of gently damping the impact. For example, hydraulic damping cylinders from the prior art can be used for this purpose.

[0045] The described rotary bearing according to the invention as an integral component of the rotor hub of the two-blade rotor allows a reversible pendulum-like movement of the two-blade rotor in the direction of the structure or tower of the wind turbine with a rotation angle of 3-5°, even in the event of high axial and radial loads on the two-blade rotor.

[0046] Such a bearing, which is itself arranged in the rotor hub, requires only a small space requirement here, because the cone angle can remain small. In addition, due to the small diameter of the conical bushing, the elastomer layer undergoes small torsional movements, thus utilizing relatively few elastic layers to achieve high torsional cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be described in more detail below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0048] Figure 1 A typical rotor hub according to the invention is shown in perspective view.

[0049] The rotor shaft (1) is firmly connected to a fixed component in the form of a carrier plate (3) in the example shown. The carrier plate (3) therefore rotates together with the rotor shaft. The carrier plate (3) is connected to two oppositely arranged joint units (5) (only one is shown). In addition, the joint unit is connected to a component (2) that is movable relative to the rotor axis and is designed so that it accommodates the carrier plate (3) and the end portion of the rotor shaft in its interior. The component (2) that forms the outer shape of the rotor hub is movably fastened to the joint unit (5) and implements the desired rotational movement in the direction of the structure of the wind power plant when a force acts on the rotor blades. The rotor blades (not shown) of the two-blade rotor are arranged at the coupling part (7) of the movable component (2). The component (2) that is movable only around the axis of rotation and has two rotor blades is limited in its movement relative to the fixed component (3) in its interior by an elastic stop device (4).

[0050] Figure 2 The side view (a) and the perspective view (b) show the Figure 1 Similar is the case with the rotary bearing or rotor hub according to the invention. Figure 2 In particular, the arrangement and design of two oppositely disposed joint units (5) on a support plate (3) are shown. Each joint unit (5) consists of a conical bushing (5.1) and a layered spring element (5.2). The conical bushing (5.1) is arranged in such a way that its wide base faces inwards and its narrow base faces outwards, wherein the cone axis is identical to the longitudinal axis of the support plate (3). The flat layered spring elements (5.2) are arranged outwards above the narrow cone bases and can thus absorb and transmit axial forces. The connection between the support plate (3) and the joint element (5.1) (5.2) is carried out via a pin-shaped portion or a bolt-shaped portion (6) correspondingly shaped in the shape of a cone, which is arranged in an extension of the support plate (3). The pin-shaped portion (6) of the fixed carrier plate (3) is connected to the inner surface of the conical bushing (5.1), and the outer surface of the conical bushing is connected to the movable component (2), so that the components (2) and (3) can be rotated relative to each other by reversible torsional deformation of the elastic conical bushing, and thus the rotor blade can be rotated relative to the structure. A stop device (4) is arranged between the components (2) and (3), which can limit the one-dimensional movement of a rotor blade (not shown) arranged on the component (2).

[0051] Figure 3 (a) shows a perspective view of the rotor shaft (1) with a firmly connected carrier plate (3). The carrier plate (3) is in turn connected to two joint units (5), more precisely in such a way that the inner elastic conical surface is respectively connected via Figure 2 1 . The movable member (2) is connected to the respective outer conical surfaces of the two conical bushings (5.1) by means of a connecting pin (6) (not shown here) shown in the drawing. For reasons of better clarity, the movable member (2) connected to the respective outer conical surfaces of the two conical bushings (5.1) is not shown. The drawing also shows three of the four pairs of stop devices (4) for the movable member (2) and their arrangement on the carrier plate (3).

[0052] Figure 3 b shows a top view of the carrier plate (3) and two oppositely disposed joint units (5) according to the present invention and their fastening parts, wherein the movable component (2) is omitted for the sake of clarity.

[0053] Figure 4 Detailed views of a connector unit (5) according to the invention are shown in perspective view (a) and side view (b)(c).

[0054] The multilayer conical element (5.1) with the cone angle (5.1.4) with its inner surface firmly surrounds a pin-shaped part or bolt-shaped part (6) formed accordingly in this area, which in turn is firmly connected to the carrier plate (3) shown below. Figure 4 As shown in (c), the conical bushing can also be connected to the pin (6) in a secure but releasable manner via a correspondingly shaped removable conical element (5.1.5) by means of a clamping screw (5.1.7), thereby making it possible to easily replace the bushing and the pin. The removable conical element (5.1.5) rests in a circular guide (recess) (5.1.6).

[0055] The lamellar spring element (5.2) as a multilayer sandwich element (5.2.1) is arranged above the conical bushing in such a way that the axes of the two components are aligned. The axially acting lamellar spring element (5.2) and the conical bushing (5.1) are surrounded by a housing (5.3). The housing (5.3) is firmly connected to the outside of the conical bushing (5.1) on the one hand, and to the movable component (2) on the other hand.

[0056] Therefore, when a force acts, an elastic torsional / rotational movement of the movable component (2) relative to the fixed component (3) can occur at the cone, which is equivalent to the rotational movement of the double-bladed rotor relative to the axis of the rotor shaft in the direction of the rotating structure of the wind power plant. Figure 4Furthermore, further geometrical dimensions (5.1.1) (5.1, 2) (5.1.3) of the tapered bushing used which are important for an optimal effect are shown.

[0057] Figure 5 (a) (b) show another embodiment of the present invention.

[0058] According to Figure 4 In contrast to the illustration of the invention, the flat sandwich element (5.2) is replaced by two hemispherical shells (5.2.2) arranged opposite each other in the axial direction, which are connected to each other via a correspondingly shaped core or bolt (9.2). The distance between the hemispherical rotation points is given by the position (9.1).

[0059] This arrangement allows for additional axial as well as radial movement of the resilient member.

[0060] Figure 6 A conical bushing (5.1) as a component of a rotating bearing according to the invention is shown in detail in a side view as it is used in an optimized embodiment of the invention. The conical bushing consists of eight elastic layers (18) (ah), which are separated from each other by firmly connected plates. In principle, bushings with 6-10 layers are also suitable. The thickness of each layer decreases from the inside to the outside. Thus, the innermost layer a has the greatest thickness (16) and the outermost layer h has the smallest thickness (17). In addition, the cone length (14) of the innermost layer a is greater than the subsequent layer b, which in turn is greater than the layer c located further outside, and so on. Thus, the innermost layer a can have a length (14) that is up to 30% greater than the length (15) of the outermost layer h.

[0061] In a particular embodiment of the conical bushing, the different layers (18) also have different Shore hardnesses, wherein the Shore hardness of the layers (18) increases by 2-5% per layer from the outside to the inside. The bushing exhibits optimal properties with regard to radial and torsional deformation of the individual elastic layers. The conical bushing (5.1) is further characterized by the given smaller and larger, inner and outer diameters (10)(11)(12)(13).

Claims

1. A rotary bearing for high load cycles as an integral component of a rotor hub of a sprung-mounted two-blade rotor for a wind turbine, the two-blade rotor being able to perform a pendulum-like movement of the rotor about a rotation angle of at least 3° under the action of simultaneously high axial and radial forces, the rotary bearing comprising: a first inner component (3) which is firmly connected to the rotor shaft (1) and thus to the rotating structure of the wind power plant; and a second outer movable component (2) having a connection area (7) for two oppositely disposed rotor blades (7a, 7b), wherein the first inner component (3) and the second movable outer component (2) which are rigidly connected are connected to one another via a rotary joint unit (5) in such a way that the rotor blades (7a, 7b) connected to the rotor hub can be reversibly moved in the direction of a structure of the wind turbine or away from the structure when a force acts on the structure, It is characterized in that (i) at least two rotating joint units (5) are arranged opposite to each other and firmly connected to each other, and each rotating joint unit is basically constructed of the following (a) at least one conical bushing (5.1) for absorbing forces acting mainly radially relative to the cone axis, each comprising a plurality of elastic layers (18), the conical bushing having a cone angle (5.1.4) which is selected such that torsional loads occurring during operation are minimized, wherein the at least one conical bushing (5.1) of the first rotary joint unit (5) is securely connected to the at least one conical bushing (5.1) of the second rotary joint unit (5) via a bolt-like connection (6), and (b) at least one elastic lamellar spring (5.2) which is arranged in such a way that it has a common axis with the at least one conical bushing and absorbs axially acting forces which cannot be absorbed by the conical bushing, (ii) the first inner component (3) which is firmly connected to the rotor shaft (1) is firmly connected to the innermost layer of the conical bushing (5.1) of the respective rotary joint unit (5) at two opposite sides, wherein the cone axis is arranged perpendicular to the axis of the rotor shaft (1), and (iii) The second external movable component (2) is firmly connected to the outermost layer of at least one conical bushing (5.1) of the respective rotary joint unit (5), so that under the action of force, reversible torsional deformation of the individual elastic layers (18) of the conical bushing (5.1) and, if possible, torsional deformation of the respective layered springs (5.2) are achieved, thereby achieving the mentioned pendulum-like motion of the double-blade rotor.

2. The rotary support according to claim 1, characterized in that: The cone angle (5.1.4) of the respective conical bushing (5) is less than 20°, in particular less than 15°, preferably 8-12°.

3. The rotary support according to claim 1 or 2, characterized in that: The at least one conical bushing (5.1) has six to ten layers (18), in particular eight layers, which are separated from one another by inelastic elements.

4. The rotary support according to any one of claims 1 to 3, characterized in that: The at least one axially acting elastic layer spring (5.2) is constructed from 3 to 8 elastic layers which are separated from one another by inelastic elements.

5. The rotary support according to any one of claims 1 to 4, characterized in that: The at least one elastic axial layer spring (5.2) is a flat sandwich element (5.2.1) which forms a structural unit with a radially acting conical bushing (5.1) of the rotary joint unit (5).

6. The rotary support according to any one of claims 1 to 4, characterized in that: The at least one elastic axial lamellar spring (5.2) is formed by at least one axially acting hemispherical element (5.2.2).

7. The rotary support according to claim 6, characterized in that: Two hemispherical elements (5.2.2) arranged axially opposite each other at a distance (9.1) form a rotary joint unit (5) together with a respectively radially acting conical bushing (5.1), wherein the hemispherical elements are preferably connected to each other via a correspondingly shaped fixing core (9.2).

8. The rotary support according to any one of claims 1 to 7, characterized in that: The first inner rigid component (3) is connected to the innermost layer of the conical bushing of the rotary joint unit (5) via a correspondingly formed bolt-type connection (6) in the region of the conical bushing (5.1).

9. The rotary support according to any one of claims 1 to 8, characterized in that: The conical bushing (5.1) is removable and replaceable.

10. The rotary support according to claim 9, characterized in that: The conical bushing (5.1) has in its interior a correspondingly shaped loose conical element (5.1.5) with means for guiding (5.1.6) and clamping (5.1.7).

11. The rotary support according to any one of claims 1 to 10, characterized in that: The outer elastic layer (18) of the conical bushing (5.1) has a lower Shore hardness than the inner elastic layer (18).

12. The rotary support according to claim 11, characterized in that: The Shore hardness of the layer (18) increases by 2-5% from the outside to the inside per layer.

13. The rotary support according to any one of claims 1 to 12, characterized in that: The inner elastic layer (18) of the conical bushing (5.1) has a greater thickness than the inner elastic layer (18).

14. The rotary support according to claim 13, characterized in that: The thickness of the layer (18) decreases by 5-10% from the inside to the outside per layer.

15. The rotary support according to any one of claims 1 to 14, characterized in that: The outer layer (18) of the conical bushing (5.1) is shorter than the inner layer.

16. The rotary support according to any one of claims 1 to 15, characterized in that: The rotary joint unit (5) has a stop element (4) which is designed and arranged in such a way that it limits the pendulum-like movement of the rotor blades (7a, 7b).

17. A rotor hub for a double-bladed rotor, characterized in that: The rotor hub has a rotation bearing according to any one of claims 1-16.

18. A wind power generation device, basically comprising a tower, a generator and a two-blade rotor capable of pendulum motion, characterized in that: The two-blade rotor has a rotor hub according to claim 17 .

Images