Lifting yoke capable of rotating rotor

Abstract

A rotor lift yoke for lifting a three-bladed rotor (6), the rotor lift yoke comprising: a lift structure (16), a first flexible elongate element (34) and a second flexible elongate element (36) and a third flexible elongate element (38) and a fourth flexible elongate element (40), the first flexible elongate element and the second flexible elongate element are both arranged to be connected to both the lifting structure and the root (104) of the first blade (10a) of the rotor, and the third flexible elongate element and the fourth flexible elongate element are both arranged to be connected to the lifting structure and the root of the second blade (10b) of the rotor. The rotor lift yoke further includes one or more length adjustment mechanisms (44, 46) arranged to adjust an effective length of the first flexible elongate element and the third flexible elongate element and / or an effective length of the second flexible elongate element and the fourth flexible elongate element. The flexible elongate elements are further arranged such that when the flexible elongate elements are attached to the roots of their respective blades, at least one point on the first flexible elongate element and the third flexible elongate element and / or at least one point on the second flexible elongate element and the fourth flexible elongate element is attached to their respective blades by an anti-slip attachment. In this manner, a rotor lifting yoke is provided that can rotate the rotor from a vertical position to a horizontal position and back again in an easy and flexible manner only by adjusting the length of the flexible elongate element.

Description

[0001] The present invention relates to a rotor lifting yoke for lifting a three - blade rotor of a wind turbine. The lifting yoke includes a lifting structure adapted to be lifted by a crane, a first flexible elongate element and a second flexible elongate element both arranged to connect to both the lifting structure and the root of a first blade of the rotor, and a third flexible elongate element and a fourth flexible elongate element both arranged to connect to both the lifting structure and the root of a second blade of the rotor. The first flexible elongate element and the second flexible elongate element are arranged such that when the first flexible elongate element and the second flexible elongate element are connected to the root of the first blade, the first flexible elongate element contacts the side of the root of the first blade facing the rotor tip, and the second flexible elongate element contacts the side of the root of the blade facing the rotor base, and the third flexible elongate element and the fourth flexible elongate element are arranged such that when the third flexible elongate element and the fourth flexible elongate element are connected to the second blade, the third flexible elongate element contacts the side of the root of the second blade facing the rotor tip, and the fourth flexible elongate element contacts the side of the root of the second blade facing the rotor base. Background Art

[0002] Lifting yokes are well - known in the field of wind turbine repair, construction, and assembly. Generally, a crane is used to transport components of a wind turbine between the ground and the top of the tower. For example, when replacing a gearbox, the crane will lift the old gearbox from the nacelle to the ground and then lift the new gearbox from the ground to the nacelle.

[0003] However, it is often difficult to connect the crane to the component itself in an easy way. Therefore, a lifting yoke is usually provided which is adapted to the component to be lifted. The lifting yoke can then be attached to the component, and the crane can then lift the combined lifting yoke and component. In one operation, the lifting yoke is connected to the component on the ground, and then the combined lifting yoke and component are lifted to the nacelle by the crane. Or the opposite occurs, where the lifting yoke is connected to the component when the component is on the wind turbine, and then the combined lifting yoke and component are lowered to the ground.

[0004] Some examples of lifting yokes used in the wind turbine industry are disclosed in US8960747, CN108190725, and WO2022112250. These yokes have adjustment mechanisms such that when the lifting yoke lifts a component, the orientation of the component relative to the yoke can be controlled and adjusted, thereby controlling and adjusting the orientation of the component relative to the wind turbine. This allows the same yoke to be used with different components from different manufacturers. For example, components of different weights and sizes need to be supported by the yoke in different ways such that the component is set in the proper orientation relative to the wind turbine. However, most known yokes are not arranged to allow for large changes in orientation.

[0005] A specific example of a lifting operation is lifting or lowering the rotor for a wind turbine. This is a complex operation that requires two cranes to rotate the rotor as it is lowered to the ground. It should be noted that for the purposes of this specification, the term "rotor" refers to the complete rotor blade assembly, which includes the rotor hub and the blades mounted on the rotor hub.

[0006] In a typical process for lowering the rotor from the nacelle to the ground, the hoist wire of the first large crane is connected to the rotor either through a rotor lifting yoke and slings that surround the blades or through a dedicated lifting bracket bolted to the rotor hub. When the rotor is lowered to the ground, the hoist wire of the second smaller crane is connected to the tip of the blade pointing downward and is used to lift the tip of the blade pointing downward so that as the rotor is lowered, the rotor pivots upward until the rotor and the blades are set horizontally. Then, the rotor can be set on the ground with the blades extending horizontally outward from the hub. When lifting the rotor from the ground to the nacelle, the hoist wire of the first crane is again connected to the rotor either through the lifting yoke with slings or through the lifting bracket bolted to the rotor. The second crane lifts the tip of the blade that will become the blade pointing downward. The first crane lifts faster than the second crane, and then the rotor will slowly rotate until the rotor and the blades are set vertically. However, in both the lifting operation and the lowering operation, multiple cranes are required to rotate the hub from a horizontal position to a vertical position or from a vertical position to a horizontal position.

[0007] It should also be noted that the solution using slings around the rotor blades poses a risk of damaging the rotor blades because when the rotor is pivoted, the blades will rotate within the slings, causing the ropes / straps of the slings to slide relative to the surface of the blades. If the friction between the blades and the ropes / straps is high, there may be a risk of damaging the blades because the movement of the ropes / straps is different from that of the blades themselves. In addition, if there are attachments on the blades themselves, such as vortex generators or other aerodynamic features, there may be a risk of these attachments being damaged.

[0008] EP2072812 discloses a proposed lifting yoke that can avoid using two cranes. However, this solution has proven to be too complex to implement because the lifting yoke is too heavy and bulky, and the connection between the rotor and the yoke is difficult to implement in a safe and reliable manner. Therefore, even though the lifting yoke is described in the patent literature, it has never been implemented in practice. US2020140236 discloses another proposed solution. Although this solution seems reasonable, it is not applicable to a three-blade rotor because the friction between the ropes and the blades is not sufficient to rotate the rotor. However, the solution proposed in US2020140236 would be applicable to a two-blade rotor. SUMMARY OF THE INVENTION

[0009] Accordingly, a first aspect of the present invention provides a rotor lifting yoke for a three - blade wind turbine rotor, which can rotate the rotor from a substantially vertical plane to a substantially horizontal plane during a lifting operation, and from a substantially horizontal plane to a substantially vertical plane.

[0010] A second aspect of the present invention provides a rotor lifting yoke that is lightweight and compact.

[0011] A third aspect of the present invention provides a rotor lifting yoke that can be used with many different types and sizes of three - blade rotors.

[0012] A fourth aspect of the present invention provides a rotor lifting yoke that has a lower risk of damaging the blades during use.

[0013] These aspects are provided at least in part by the rotor lifting yoke according to claim 1. In this way, a rotor lifting yoke is provided that allows the rotor to be rotated from a vertical orientation to a horizontal orientation in an easy manner.

[0014] It should be noted that in this specification, the term "anti - slip attachment" should be understood as a form of attachment that ensures a constant position between the flexible elongated element and the blade, where there is no displacement at a specific position between the flexible elongated element and the root of the blade. In some embodiments, the anti - slip attachment is provided by a bracket that is fixed to the flexible elongated element and the root of the blade. In some embodiments, the anti - slip attachment is provided by the friction between a part of the flexible elongated element and the root of the blade. It should be clear that in order to provide an anti - slip attachment in the case of a friction connection, the frictional force should exceed the rotational force generated by the weight of the rotor.

[0015] In some embodiments, the one or more length - adjusting mechanisms are remotely controllable during the lifting operation. The term "effective length" in this specification should be understood to strengthen that different forms of length - adjusting mechanisms can be provided, and these length - adjusting mechanisms fall within the scope of the present invention. For example, in some embodiments, the length of the flexible elongated element is constant, but the end of the flexible elongated element connected to the lifting structure can alternatively be displaced. In this way, the length of the flexible elongated element is constant, but the effective length of the element will change as the end of the element is displaced. This can be achieved, for example, by displacing the cross - beam to which the end of the flexible elongated element is attached. In such an embodiment, the length is constant, but the effective length is variable.

[0016] In some embodiments, the first flexible elongate element and the second flexible elongate element are parts of the same flexible elongate element and / or the third flexible elongate element and the fourth flexible elongate element are parts of the same flexible elongate element. Thus, for example, rather than providing separate ropes for the front portion and the rear portion of the blade, the same rope that contacts both the front portion and the rear portion of the blade can be provided.

[0017] In some embodiments, the first flexible elongate element and the second flexible elongate element are each configured to be connected to the root of the first blade by one or more brackets, the one or more brackets connected to the first flexible elongate element and the second flexible elongate element are configured to be detachably attached to the root of the first blade, and wherein the third flexible elongate element and the fourth flexible elongate element are each configured to be connected to the root of the second blade by one or more brackets, the one or more brackets connected to the third flexible elongate element and the fourth flexible elongate element are configured to be detachably attached to the root of the second blade.

[0018] In some embodiments, the first flexible elongate element is configured to be attached to the root of the first blade by a first bracket, the second flexible elongate element is configured to be attached to the root of the first blade by a second bracket, the third flexible elongate element is configured to be attached to the root of the second blade by a third bracket, and the fourth flexible elongate element is configured to be attached to the root of the second blade by a fourth bracket.

[0019] In some embodiments, the first flexible elongate element and the second flexible elongate element are configured to be connected to the root of the first blade by a first bracket, and the third flexible elongate element and the fourth flexible elongate element are configured to be connected to the root of the second blade by a second bracket.

[0020] In some embodiments, the brackets are configured to be respectively attached to the roots of the first blade and the second blade by bolts, the bolts being the bolts that connect the roots of the blades to the rotor hub.

[0021] In some embodiments, the rotor lifting yoke further includes a first spacer element and a second spacer element. The first flexible elongate element and the second flexible elongate element are parts of the same flexible elongate element, and the same flexible elongate element for forming the first flexible elongate element and the second flexible elongate element is arranged to wind around the root of the first blade by at least 540 degrees. The third flexible elongate element and the fourth flexible elongate element are parts of the same flexible elongate element, and the same flexible elongate element for forming the third flexible elongate element and the fourth flexible elongate element is arranged to wind around the root of the second blade by at least 540 degrees. The first spacer element is arranged to be placed between the first flexible elongate element and the root of the first blade when lifting the rotor, and the second spacer element is arranged to be placed between the third flexible elongate element and the root of the second blade when lifting the rotor. And the first spacer element and the second spacer element respectively have a dimension of at least 500 mm in a direction perpendicular to the surface of the root of the first blade and a dimension of at least 500 mm in a direction perpendicular to the surface of the root of the second blade. In this way, the tension in the first flexible elongate element and the third flexible elongate element is reduced. In addition, during lifting, an undesired rotation of the root of the blade relative to the flexible elongate element is prevented because the torque around the center of gravity of the rotor caused by gravity will be reduced. In some embodiments, the distance is greater than 600 mm, greater than 700 mm or greater than 800 mm. In some embodiments, the distance is determined by the size of the rotor to be lifted. In some cases, the distance is 20%, 25% or 30% larger than the root diameter of the blade of the rotor to be lifted.

[0022] In some embodiments, the first spacer element is fastened to the first flexible elongate element and / or the second flexible elongate element, and the second spacer element is fastened to the third flexible elongate element and / or the fourth flexible elongate element. In this way, the movement of the spacer element relative to the flexible elongate element is prevented. The term "fastened to" in this specification should be understood as two elements being connected together such that the two elements move together at the fastened position. The term "fastening" is a displacement constraint in at least one dimension, and not necessarily a rotation constraint or a displacement constraint in all directions. An example of a fastening connection is a loop on the spacer element through which a rope is fed. The spacer element can be displaced along the rope; however, the loop cannot be displaced away from the rope. Therefore, the point where the spacer element is attached to the loop will remain in a controlled position relative to the rope but can slide along the rope. Other forms of fastening are also conceivable.

[0023] In some embodiments, a first spacer element is fastened to both a first flexible elongate element and a second flexible elongate element such that the first spacer element forms part of the same flexible elongate element that is arranged to wrap around the root of the first blade by at least 540 degrees, and a second spacer element is fastened to both a third flexible elongate element and a fourth flexible elongate element such that the second spacer element forms part of the same flexible elongate element that is arranged to wrap around the root of the second blade by at least 540 degrees. In this case, the "same flexible elongate element" is not flexible along its entire length, but the element is still able to wrap around the root of the blade.

[0024] In some embodiments, the first spacer element and the second spacer element include a blade-facing surface, the curvature of which matches the curvature of the root of the blade. In this way, the forces between the spacer element and the root of the blade can be distributed over an area. In some embodiments, the length of the blade-facing surface is greater than 400 mm, greater than 500 mm, or greater than 600 mm.

[0025] In some embodiments, during a lifting operation, the first flexible elongate element contacts the first spacer element at the farthest point at which the first spacer element extends from the surface of the root of the first blade, and the third flexible elongate element contacts the second spacer element at the farthest point at which the second spacer element extends from the surface of the root of the second blade.

[0026] In some embodiments, the first spacer element and the second spacer element are arranged such that during a lifting operation when the rotor is in a horizontal position, in the plane of the diameter of the root of the first blade, the horizontal distance between the center of the root of the first blade and the first flexible elongate element is at least 70% of the diameter of the root of the first blade, and in the plane of the diameter of the root of the second blade, the horizontal distance between the center of the root of the second blade and the third flexible elongate element is at least 70% of the diameter of the root of the second blade.

[0027] In some embodiments, the rotor lifting yoke is arranged such that during a lifting operation in which the rotor lifting yoke lifts the rotor, at least a portion of the first flexible elongate element or at least a portion of the second flexible elongate element and at least a portion of the third flexible elongate element or at least a portion of the fourth flexible elongate element respectively contact a portion of the root of the first blade and a portion of the root of the second blade, and the portions of the root of the first blade and the root of the second blade that are contacted are located below the center of the root of the respective blade.

[0028] In some embodiments, the anti-slip attachment between the flexible elongate element and the root of the blade is located on the root of the blade, above or below the line connecting the side of the blade facing the rotor tip and the side of the root of the blade facing the rotor base. In some embodiments, the anti-slip attachment between the first flexible elongate element and / or the third flexible elongate element and the root of the blade is located at a point that is set beyond the side facing the rotor tip in the direction from the side facing the rotor tip to the side facing the rotor base, and the anti-slip attachment between the second flexible elongate element and / or the fourth flexible elongate element and the root of the blade is located at a point that is set beyond the side facing the rotor base in the direction from the side facing the rotor base to the side facing the rotor tip.

[0029] In some embodiments, the length adjustment mechanism includes one or more winch mechanisms that are connected to one or more of the first flexible elongate element, the second flexible elongate element, the third flexible elongate element, or the fourth flexible elongate element. In some embodiments, the winch mechanism includes a motor and a pulley. In some embodiments, the motor is a hydraulic motor. In some embodiments, the motor is an electric motor. In some embodiments, the motor is powered by a battery attached to the lifting yoke. In the case where the motor is a hydraulic motor, the hydraulic power supply can be powered by a battery-driven pump.

[0030] In some embodiments, the lifting structure includes a first crossbeam and a second crossbeam that are arranged parallel to each other and spaced apart from each other, and the second flexible elongate element and the fourth flexible elongate element are connected to the first crossbeam, and the first flexible elongate element and the third flexible elongate element are connected to the second crossbeam.

[0031] This specification also discloses a crane for lifting a rotor by means of a lifting yoke according to any one or any combination of the above embodiments.

[0032] In some embodiments of the crane, at least a portion of the first flexible elongate element and / or at least a portion of the second flexible elongate element are in contact with the root of the first blade, and at least a portion of the third elongate element and / or at least a portion of the fourth elongate element are in contact with the root of the second blade.

[0033] It should be emphasized that when used in this specification, the terms "comprising / including / consisting of" are used to specify the presence of the stated features, wholes, steps, or components, but do not preclude the presence or addition of one or more other features, wholes, steps, components, or groups thereof. Description of the Drawings

[0034] In the following, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings. It should be emphasized that the shown embodiments are for illustrative purposes only and should not be used to limit the scope of the present invention.

[0035] Figure 1 A perspective view of a schematic wind turbine tower according to a first embodiment of the present invention is shown, in which the rotor is being lowered by a crane and a rotor lifting yoke.

[0036] Figure 2 Shows Figure 1 A partially enlarged perspective view of the rotor lifting yoke and the rotor.

[0037] Figure 3 Shows Figure 1 A partially enlarged perspective view of the rotor lifting yoke and the rotor, with the rotor in a lower position and partially rotated.

[0038] Figure 4 Shows Figure 1 A partially enlarged perspective view of the rotor lifting yoke and the rotor, with the rotor in an even lower position and fully rotated so that the rotor and the blades are set horizontally.

[0039] Figure 5 A partially enlarged perspective view of a wind turbine tower, rotor, and rotor lifting yoke according to a second embodiment of the present invention is shown.

[0040] Figure 6 And Figure 7 Respectively schematically show a third embodiment of the rotor lifting yoke according to the present invention, with the rotor in a vertical position and a horizontal position respectively.

[0041] Figure 8 And Figure 9 Schematically show a fourth embodiment of the rotor lifting yoke according to the present invention, with the rotor in a vertical position and a horizontal position, and this fourth embodiment is similar to the Figure 5 Shown embodiment.

[0042] Figure 10 And Figure 11 Schematically show a fifth embodiment of the rotor lifting yoke according to the present invention, with the rotor in a vertical position and a horizontal position, and this fifth embodiment is similar to the Figures 1 to 4 Shown embodiment.

[0043] Figure 12 And Figure 13 Schematically show the vertical position and the horizontal position of the rotor lifted by a sixth embodiment of the rotor lifting yoke according to the present invention.

[0044] Figure 14 And Figure 15Schematically shows the vertical and horizontal positions of a rotor lifted by a seventh embodiment of a rotor lifting yoke according to the present invention.

[0045] Figure 16 Schematically shows the vertical position of a rotor lifted by an eighth embodiment of a rotor lifting yoke according to the present invention. Detailed Description

[0046] Figures 1 to 4 Schematically illustrates a first embodiment of a lifting yoke 1 that enables a rotor to rotate according to the present invention, and the lifting yoke 1 is in operation.

[0047] The accompanying drawings schematically show a wind turbine tower 2, a nacelle 4, and a rotor 6. The rotor includes a rotor hub 8 and three blades 10a, 10b, 10c attached to the rotor hub 8. A crane hook 12 is used to lift the rotor through the lifting yoke 1, and the crane hook is lifted by a crane wire 14 of a crane (not shown).

[0048] The lifting yoke includes a lifting structure 16, which is in the form of a first crossbeam 18 and a second crossbeam 20. The second crossbeam is arranged parallel to the first crossbeam and offset relative to the first crossbeam. This offset is ensured by an offset beam 22, which is attached to the first crossbeam and extends perpendicularly from the first crossbeam. The second crossbeam is pivotally supported at the end of the offset beam 22 by a shackle connection 24. The ends 26, 28 of the first crossbeam and the end 30 of the offset beam spaced apart from the first crossbeam are connected to a sling or cable 32, which is connected to the crane hook 12. When the crane moves the hook up and down, the lifting structure 16 will thus also move up and down.

[0049] The lifting yoke further includes a first rope 34 and a second rope 36 attached to the first blade 10a, and a third rope 38 and a fourth rope 40 attached to the second blade 10b. The first rope 34 and the third rope 38 are also attached near the opposite ends of the second crossbeam, and the second rope 36 and the fourth rope 40 are also attached near the opposite ends of the first crossbeam. In this embodiment, a bracket 42 is fixed to a bolt ring that connects the first blade to the hub. A second bracket (not visible) is fixed to a bolt ring that connects the second blade to the hub. The first rope and the second rope are attached to the first bracket 42, and the third rope and the fourth rope are attached to the second bracket. In this way, these ropes are fixed in place relative to the roots of the corresponding blades, and these ropes are attached to the roots of the corresponding blades at the position of the brackets.

[0050] In this embodiment, the first crossbeam further includes two winch assemblies 44, 46. The first winch assembly 44 is connected to one end of the second rope 36, and the second winch assembly 46 is connected to one end of the fourth rope 40. In the current embodiment, the winch assemblies are driven by battery-powered electric motors that can be remotely controlled. When the winch assemblies are operated, the lengths of the second rope and the fourth rope can be adjusted.

[0051] When the lengths of the second rope and the fourth rope are adjusted, the rotor will rotate because the first rope, the second rope, the third rope, and the fourth rope are fixed in place relative to the rotor. In Figure 2 it, the rotor is suspended such that the rotor is disposed in a substantially vertical plane. In Figure 3 it, the lengths of the second rope and the fourth rope have been increased. This causes the rotor to rotate outward, and the blades pointing downward begin to pivot outward away from the wind turbine tower. In Figure 4 it, the lengths of the second rope and the fourth rope have been further increased, causing the rotor to rotate such that the rotor is substantially disposed in a horizontal plane. In this position, the rotor base is substantially horizontally disposed and faces downward. In this position, the rotor can be disposed on the ground or on a support structure on the ground. The entire operation can be performed by the same crane without the need for a separate crane to pivot the tips of the blades pointing downward outward.

[0052] Those skilled in the art should be aware that different mechanisms and devices can be provided to control the relative lengths of the ropes. For example, the winch mechanism can be attached to the first rope and the third rope instead of the second rope and the fourth rope. In this example, the lengths of the first rope and the third rope need to be decreased to obtain the same rotation as in Figures 1 - 4 it. In another example, the winch mechanism can be connected to all four ropes. In this example, the first rope and the third rope can be shortened, and the second rope and the fourth rope can be lengthened. In another example, the shackle connection between the offset beam 22 and the second crossbeam 20 can be formed as part of a winch mechanism that can extend or shorten the distance between the first crossbeam and the second crossbeam. In this example, the lengths of the ropes between the crossbeam and the rotor will be constant, but the distance between the two crossbeams will be variable. Those skilled in the art should understand that different solutions are possible.

[0053] It should be noted that in this embodiment, although it is difficult to see in the drawings, the bracket 42 is an arc-shaped metal plate which has a plurality of bolt holes corresponding to the bolt type of the bolts that connect the blade 10a to the rotor hub. When it is necessary to attach the bracket to the blade, some of the bolts that connect the blade to the hub are removed, the bracket is placed in place, and then the bolts are passed through the bracket, through the blade and inserted into the hub. Then, one end of the first rope and one end of the second rope are attached at opposite ends of the bracket 42. Then the same process is repeated for the second blade 10b and the third and fourth ropes.

[0054] Another feature to note in the current embodiment is that the second crossbeam 20 is pivotally supported at the end of the offset beam 22 relative to the first crossbeam 18. In this way, the beam will pivot and will automatically balance the loads in the ropes 34, 38 which are attached between the second crossbeam 20 and the first blade 10a and between the second crossbeam 20 and the second blade 10b. If the second crossbeam had been fixed relative to the first crossbeam, there could be a difference between the loads in the ropes attached to the first blade and the second blade. However, when the beam is pivotally attached to the crane support, the loads will be automatically balanced.

[0055] In some rotors, the bolts that connect the blades to the rotor hub are inaccessible. In such cases, it is not easy to directly attach the bracket to the root of the blade. In these cases, one way to establish a non-slip connection between the rope and the root of the blade is to increase the friction between the rope and the root of the blade to which the rope is connected. One way to do this is to increase the coefficient of friction of the material of the rope relative to the material of the root of the blade. For example, the rope can be covered with a rubber-like substance which has a high coefficient of friction relative to the fiberglass material of the root of the blade. When the length of the rope is adjusted, the surface of the root of the blade will follow the rope and the rotor will be pivoted as if the rope were fixed to the rotor through the bracket. It should be clear to those skilled in the art that the geometry of the rotor and the position of the rope on the blade will have a great influence on the torque forces on the rotor during the rotation operation. In the case where the rotor is suspended in a vertical plane, the torque forces will be quite low because the rotor will be balanced. However, when the rotor is pivoted, the center of gravity will change. If the center of gravity is offset in the horizontal plane from the center of the roots of the first and second blades, the torque force that attempts to pivot the third blade downward will increase. In such cases, a higher frictional force between the blade and the rope is required to maintain the position of the rotor. Based on the known geometry of the rotor, the expected torque forces can be easily calculated. The frictional force can also be easily calculated through the coefficient of friction and the expected normal force based on the weight of the rotor. Therefore, the appropriate material and size of the rope can be determined.

[0056] In another embodiment, as Figure 5As shown, a first identical continuous rope 60 is wound 540 degrees around the root of the first blade 10a, and a second identical continuous rope 62 is wound 540 degrees around the root of the second blade 10b. In this way, when the rotor is lifted, the ropes will tighten around the roots of the blades to increase the friction between the blades and the ropes. In some cases (not shown), the ropes can be wound around the roots of the blades two or even more times to further increase the amount of contact between the ropes and the blades. In this figure, a first spacer element 61 is provided between the first blade 10a and the first identical continuous rope 60, and a second spacer element 63 is provided between the second blade 10b and the second identical continuous rope 62. Refer to Figure 8 、 9 、14 and 15 for a more detailed description of the function of the spacer elements.

[0057] In another embodiment (not shown), a strip or other form of circular bracket can be tightened around the circumference of the root of the blade. For example, a strip having a rubber-like surface that abuts the blade surface can be tightened by means of a ratchet mechanism until the strip presses very tightly against the blade surface. Then, as Figures 1 - 4 shown, the ropes can be attached to the strip by fastening to attachment points on the strip.

[0058] It should be noted that in Figure 5 this case, the same rope is used on either side of the rotor. However, there are still a forward portion 64 and a backward portion 66 of the rope. Therefore, when understanding the claims, the front portion 64 can be considered as the first flexible elongated element, and the rear portion can be considered as the second flexible elongated element.

[0059] Figure 6 and Figure 7 schematically illustrate a third embodiment of a lifting yoke 100 for lifting the rotor of a wind turbine. In this case, for illustrative purposes, the rotor hub 102 is shown, and a cross-section through the root 104 of one blade is shown. It should be clear to those skilled in the art that similar devices are provided on the other side of the rotor hub and are connected to the blades on the other side of the rotor hub.

[0060] In this embodiment, a single rope 106 is used instead of two separate ropes attached to a bracket on the rotor hub. One end of the rope 106 is attached to the first crossbeam 108 and the second end of the rope is attached to the second crossbeam 110. The rope is arranged to pass under the root of the blade so as to support the weight of the rotor hub. A bracket 112 is provided which fastens a portion of the rope to the root of the blade. The bracket can be arranged in many different ways. In one case, a bracket can be provided which clamps a portion of the rope between two plates, both of which are fixed to the rotor hub by bolts connecting the blade and the hub.

[0061] It should be noted that in this case, even though a single rope is used, the rope can still be considered to comprise two separate elements which are joined together into one element. The first rope portion 106a contacts the side 114 of the root of the blade facing the rotor tip, and the second rope portion 106b contacts the side 116 of the root of the blade facing the rotor base. In this embodiment, the bracket is fastened to the blade at a point between the side facing the rotor tip and the side facing the rotor base and at a point below the center of the blade. In this way, when the rotor is rotated, the bracket will rotate upwards but remain below the center of the blade. If the bracket were attached at a higher position on the structure, the bracket would rotate upwards beyond the center of the blade and create an additional load on the rope. It should also be noted that when the rotor is held in a horizontal position ( Figure 7 ), the dimensions of the bracket, the position at which the first rope portion 106a is held relative to the blade surface, and the geometry of the rotor will have an effect on the tension in the first rope portion 106a. The further the rope is held from the surface of the root of the blade, the lower the tension in the first rope portion 106a will be, while the tension in the second rope portion 106b will be higher. This principle also applies to other embodiments disclosed in this application. By adjusting this distance, the tension in each rope can be designed more specifically.

[0062] It should be noted that the side 114 facing the rotor tip is so named because this side faces the tip 118 of the rotor hub 102. The side 116 facing the rotor base is so named because this side faces the base 120 of the rotor hub 102. It should be noted that when the rotor rotates, the side of the blade facing the rotor tip and the side facing the rotor base will also rotate. Furthermore, it can be seen that one of the ropes is always in contact with either the side facing the rotor tip or the side facing the rotor base.

[0063] It can also be noted that in Figure 6 and Figure 7In the embodiment, the rope between the crossbeam and the support does not change its physical length, but changes the position of the crossbeam, thereby allowing the rotor to rotate. In this case, a more complex lifting structure needs to be provided, and a mechanism needs to be provided between the lifting structure of the yoke and the crossbeam. However, the final effect is the same as adjusting the lengths of the first and second ropes. Therefore, the claims specify adjusting the effective length of the rope. This should include the case where the crossbeam is disposed between the rope and the displacement mechanism and the ends of the rope are displaced to cause a change in the effective length of the rope.

[0064] Figure 8 and Figure 9 shows a schematic view of a fourth embodiment of a rotor lifting yoke 200 similar to that shown in Figure 5 In this case, the rope 202 wraps around the root of the blade 204 by 540 degrees. In this embodiment, no support is required because the friction between the blade and the rope is sufficient to ensure a non-slip connection between the rope and the blade. In the case where the friction is not high enough, the rope can additionally wrap around the blade for some time, thereby wrapping around the blade by 900 degrees. In this embodiment, a spacer element 206 is disposed between the rope 202 and the surface 208 of the root of the blade 204. In this way, the offset between the tip-facing rope portion 202a and the surface of the blade is increased. Due to this spacer element, when the rotor is in its horizontal position, the tension in the tip-facing rope portion will decrease, and the tension in the rope portion 202b facing the rotor base will increase because the torque acting on the rotor due to gravity will be more evenly distributed between the two rope portions. In the absence of the spacer element, the tension in the tip-facing rope portion will be so high that it is impossible to hold the rotor in place only due to friction. It has been found that when the rotor is in the horizontal position, the offset D2 needs to be at least 20% of the diameter D1 of the root of the blade, and this offset D2 is the offset from the surface of the root of the blade to the portion of the spacer element that contacts the tip-facing portion 202a of the rope. For modern blades, this offset is typically greater than 500 mm. As the rotor gets larger, the spacing offset D2 will become larger and larger.

[0065] The spacer element 206 in the figure is provided with a blade-facing surface 210 which is curved to conform to the root of the blade. In this way, the force applied by the rope to the spacer element will be distributed over a larger area of the surface of the root of the blade. Additionally, the greater the length of the curved portion 210 and, generally, the greater the area of contact of the curved portion with the root of the blade, the more stable the position of the spacer element will be. In some cases, a coating that increases friction can be applied to the blade-facing surface of the spacer element to hold the spacer element in place on the blade surface. In the current embodiment, the spacer element is provided in a generally triangular configuration; however, it should be clear that other embodiments can be provided. As a non-limiting example, a spacer element in the form of a T-shaped element can be envisioned, where the upper portion of the T is curved to conform to the curvature of the blade and the root of the T is arranged to point downward when the rotor is in its vertical position. When the rotor rotates to the horizontal position, the root of the T will rotate to point horizontally outward so as to also push the tip-facing portion of the rope away from the surface of the blade.

[0066] Figure 10 and Figure 11 A fifth embodiment 300 of a lifting yoke is shown. In this example, rather than attaching one bracket to the root of the blade, two separate brackets 304, 306 are attached to the root of the blade 302. A first rope 308 is attached to the first bracket 304 and a second rope 310 is attached to the second bracket.

[0067] Figure 12 and Figure 13 A sixth embodiment 400 of a lifting yoke is shown. In this example, ropes 402, 404 are again attached to two separate brackets 406, 408 on the root of the blade 410, but the ropes cross each other to connect to opposite sides of the root of the blade. In this way, the contact surface between the ropes and the blade is increased. This will reduce the force on the brackets themselves and will align the force with the circumference of the blade. In Figure 10 and Figure 11 example, at one position ( Figure 11 ), the load will be supported almost entirely by one bracket 304 and the direction of the load will be almost radial along the root of the blade. This will require a stronger bracket than the Figure 12 and Figure 13 solutions.

[0068] In this embodiment, it can be said that the bracket 406 connected to the first cable 402 is attached at a point on the root of the blade, and in the direction from the side 114 of the root of the blade facing the rotor tip towards the side 116 of the root of the blade facing the rotor base, this point is positioned "beyond" the side 114 of the root of the blade facing the rotor tip. Similarly, the bracket 408 connected to the second cable 404 is attached to the root of the blade at a point, and in the direction from the side of the blade facing the rotor base towards the side of the blade facing the rotor tip, this point is positioned "beyond" the side 116 of the root of the blade facing the rotor base. In this embodiment, the bracket is positioned "beyond" the corresponding side of the root of the blade by approximately 135 degrees. In contrast, in Figure 10 and 11 in the embodiment, the bracket is positioned "beyond" the corresponding side of the root of the blade by approximately 45 degrees. In another embodiment (not shown), the bracket can be positioned even more than 135 degrees beyond the corresponding side of the root of the blade.

[0069] Figure 14 and Figure 15 illustrate another embodiment 500 of a rotor lifting yoke similar to Figure 8 and Figure 9 However, in this case, instead of having a spacer element between the surface and the cable, the spacer element 506 in this embodiment is an integral part of the cable element 502. The part 502a of the cable facing the rotor tip is connected to the "highest" part 508 of the spacer element by a fastening member 510. Similarly, the part 502b of the cable facing the rotor base first winds 360 degrees around the root of the blade and then is attached to one end 512 of the spacer element. In this way, the spacer element is arranged between the part 502b of the cable facing the rotor base and the part 502a of the cable facing the tip. Due to this arrangement, the position of the spacer element can be precisely controlled and held in place by the cable itself.

[0070] Figure 16 illustrates a similar to Figure 14 and Figure 15Another embodiment 600 of the embodiment. In this case, the part 602b of the rope facing the rotor base is first attached to one end 604 of the spacer element 606. Then, the part 602a of the rope facing the tip winds around the root of the blade approximately 360 degrees (also around the spacer element), and is then attached to the other end 608 of the spacer element 606. As with other embodiments having a spacer element, when the rotor rotates to its horizontal position, the spacer element offsets the part 602a of the rope facing the rotor tip from the surface of the blade. This equalizes the tension in the two rope parts and allows the rotor to be rotated and held in a stable position. It should be clear to those skilled in the art that the spacer element can be arranged in different ways, and the rope can be connected or fastened to the spacer element in different ways.

[0071] It should be clear that the above different concepts can be combined in different ways within the scope of the present invention.

[0072] In the above discussion, a rope is used between the rotor and the lifting structure. However, it should be clear to those skilled in the art that in addition to ropes, other elements are also suitable for this application. In the claims, the term "flexible elongated element" is used. This should cover ropes, chains, belts, slings, wires, cables, etc. or combinations thereof. Those skilled in the art will also be able to provide different options and different connection options between the element and the blade. For example, if the flexible elongated element is a chain, a suitable protective element is required. It should also be noted that the entire "flexible elongated element" does not need to be flexible. It is possible that some parts of the "flexible elongated element" are rigid, but are shaped to fit the surface of the rotor blade. For example, this is Figures 14 - 16 the case in the embodiment, where the spacer element forms part of the "flexible elongated element".

[0073] It should be noted that the drawings and the above description have shown the exemplary embodiments in a simple and schematic manner. Many specific mechanical details are not shown because those skilled in the art should be familiar with these details, and these details will only unnecessarily complicate this description. For example, the specific materials and components used and the specific manufacturing processes are not described in detail because it is considered that those skilled in the art will be able to find suitable materials, components and suitable methods to manufacture the rotor lifting yoke according to the present invention.

Claims

1. A rotor lifting yoke for lifting the rotor of a wind turbine having three blades, the lifting yoke comprising: a. A lifting structure adapted to be lifted by a crane, b. A first flexible elongate element and a second flexible elongate element, both the first flexible elongate element and the second flexible elongate element being arranged to be connected to both the lifting structure and the root of the first blade of the rotor, and c. A third flexible elongate element and a fourth flexible elongate element, both the third flexible elongate element and the fourth flexible elongate element being arranged to be connected to both the lifting structure and the root of the second blade of the rotor, d. The first flexible elongate element and the second flexible elongate element being arranged such that when the first flexible elongate element and the second flexible elongate element are connected to the root of the first blade, the first flexible elongate element contacts the side of the root of the first blade facing the rotor tip, and the second flexible elongate element contacts the side of the root of the blade facing the rotor base, and e. The third flexible elongate element and the fourth flexible elongate element being arranged such that when the third flexible elongate element and the fourth flexible elongate element are connected to the second blade, the third flexible elongate element contacts the side of the root of the second blade facing the rotor tip, and the fourth flexible elongate element contacts the side of the root of the second blade facing the rotor base, f. Characterized in that the rotor lifting yoke further comprises one or more length adjustment mechanisms arranged to adjust the effective length of the first flexible elongate element and the third flexible elongate element and / or to adjust the effective length of the second flexible elongate element and the fourth flexible elongate element, and g. The rotor lifting yoke and the flexible elongate elements are further arranged such that when the flexible elongate elements are attached to the roots of their respective blades, at least one point on the first flexible elongate element and the third flexible elongate element and / or at least one point on the second flexible elongate element and the fourth flexible elongate element are attached to their respective blades by anti-slip attachments.

2. The rotor lifting yoke according to claim 1, wherein, The first flexible elongate element and the second flexible elongate element are part of the same flexible elongate element, and / or the third flexible elongate element and the fourth flexible elongate element are part of the same flexible elongate element.

3. The rotor lifting yoke according to claim 1 or 2, wherein, The first flexible elongate element and the second flexible elongate element are arranged to be connected to the root of the first blade by one or more brackets, the one or more brackets connected to the first flexible elongate element and the second flexible elongate element being arranged to be detachably attached to the root of the first blade, and the third flexible elongate element and the fourth flexible elongate element are arranged to be connected to the root of the second blade by one or more brackets, the one or more brackets connected to the third flexible elongate element and the fourth flexible elongate element being arranged to be detachably attached to the root of the second blade.

4. The rotor lifting yoke according to claim 3, wherein, The first flexible elongate element is arranged to be attached to the root of the first blade via a first bracket, the second flexible elongate element is arranged to be attached to the root of the first blade via a second bracket, the third flexible elongate element is arranged to be attached to the root of the second blade via a third bracket, and the fourth flexible elongate element is arranged to be attached to the root of the second blade via a fourth bracket.

5. The rotor lifting yoke according to claim 3, wherein, The first flexible elongate element and the second flexible elongate element are both arranged to be connected to the root of the first blade via a first bracket, and the third flexible elongate element and the fourth flexible elongate element are both arranged to be connected to the root of the second blade via a second bracket.

6. The rotor lifting yoke according to any one of claims 3, 4, and 5, wherein, The brackets are arranged to be attached to the roots of the first blade and the second blade respectively by bolts, and the bolts are the bolts for connecting the roots of the blades to the rotor hub.

7. The rotor lifting yoke according to claim 2, wherein, The rotor lifting yoke further includes a first spacer element and a second spacer element. The first flexible elongate element and the second flexible elongate element are parts of the same flexible elongate element. The same flexible elongate element for forming the first flexible elongate element and the second flexible elongate element is arranged to wind around the root of the first blade by at least 540 degrees. The third flexible elongate element and the fourth flexible elongate element are parts of the same flexible elongate element. The same flexible elongate element for forming the third flexible elongate element and the fourth flexible elongate element is arranged to wind around the root of the second blade by at least 540 degrees. The first spacer element is arranged to be placed between the first flexible elongate element and the root of the first blade when lifting the rotor. The second spacer element is arranged to be placed between the third flexible elongate element and the root of the second blade when lifting the rotor. And the first spacer element and the second spacer element respectively have a dimension of at least 500 mm in a direction perpendicular to the surface of the root of the first blade and a dimension of at least 500 mm in a direction perpendicular to the surface of the root of the second blade.

8. The rotor lifting yoke according to claim 7, wherein, The first spacer element is fastened to the first flexible elongate element and / or the second flexible elongate element, and the second spacer element is fastened to the third flexible elongate element and / or the fourth flexible elongate element.

9. The rotor lifting yoke according to claim 7 or 8, wherein, The first spacer element is fastened to both the first flexible elongate element and the second flexible elongate element, such that the first spacer element becomes a part of the same flexible elongate element arranged to wind around the root of the first blade by at least 540 degrees, and the second spacer element is fastened to both the third flexible elongate element and the fourth flexible elongate element, such that the second spacer element becomes a part of the same flexible elongate element arranged to wind around the root of the second blade by at least 540 degrees.

10. The rotor lifting yoke according to any one of claims 7-9, wherein, The first spacer element and the second spacer element include surfaces facing the blade, and the curvature of the surfaces facing the blade matches the curvature of the root of the blade.

11. The rotor lifting yoke according to claim 10, wherein, The length of the surface facing the blade is greater than 500 mm.

12. The rotor lifting yoke according to any one of claims 7-11, wherein, During the lifting operation, the first flexible elongated element contacts the first spacer element at the farthest point where the first spacer element extends from the surface of the root of the first blade, and the third flexible elongated element contacts the second spacer element at the farthest point where the second spacer element extends from the surface of the root of the second blade.

13. The rotor lifting yoke according to any one of claims 7-12, wherein, The first spacer element and the second spacer element are arranged such that during the lifting operation when the rotor is in a horizontal position, in the plane of the diameter of the root of the first blade, the horizontal distance between the center of the root of the first blade and the first flexible elongated element is at least 70% of the diameter of the root of the first blade, and in the plane of the diameter of the root of the second blade, the horizontal distance between the center of the root of the second blade and the third flexible elongated element is at least 70% of the diameter of the root of the second blade.

14. The rotor lifting yoke according to any one of claims 1 to 13, wherein, The rotor lifting yoke is arranged such that during the lifting operation of lifting the rotor by the rotor lifting yoke, at least a part of the first flexible elongated element or the second flexible elongated element and at least a part of the third flexible elongated element or the fourth flexible elongated element respectively contact a part of the root of the first blade and a part of the root of the second blade, and the parts of the root of the first blade and the root of the second blade that are contacted are located below the centers of the roots of the respective blades.

15. The rotor lifting yoke according to any one of claims 1 to 14, wherein, The length adjustment mechanism includes one or more winch mechanisms, and the one or more winch mechanisms are connected to one or more of the first flexible elongated element, the second flexible elongated element, the third flexible elongated element, and the fourth flexible elongated element.

16. The rotor lifting yoke according to any one of claims 1 to 15, characterized in that The lifting structure includes a first cross beam and a second cross beam, the first cross beam and the second cross beam are arranged parallel to each other and spaced apart from each other, and the second flexible elongated element and the fourth flexible elongated element are connected to the first cross beam, and the first flexible elongated element and the third flexible elongated element are connected to the second cross beam.

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