LIFTING APPARATUS FOR A LIFTING CRANE

Abstract

Provided is a lifting apparatus for a lifting crane, adapted to carry an elongated component having a non-circular cross section extending over the major part of its length, especially a rotor blade of a wind turbine, including a frame with at least one holder for holding the component with a horizontal orientation, wherein a pitching system for pitching the component around its longitudinal axis is provided.

Claims

1. A lifting apparatus for a lifting crane, adapted to carry an elongated component comprising a non-circular cross section extending over the major part of its length, especially a rotor blade of a wind turbine, comprising a frame with at least one holding means or holder for holding the component with an essentially horizontal orientation, characterized in that a pitching system for pitching the component around its longitudinal axis is provided.

2. The lifting apparatus according to claim 1, wherein the at least one holding means or holder as a part of the pitching system is pivotable around a rotation axis.

3. The lifting apparatus according to claim 2, wherein it comprises at least two support arms, whereby separate holding means or holder adapted for a synchronized rotation are arranged at each support arm, or whereby the holding means or holder extends from one support arm to the other.

4. The lifting apparatus according to claim 1, wherein the at least one or each holding means or holder is adapted to hold the component in a region with a non-circular cross section.

5. The lifting apparatus according to claim 1, wherein the or each holding means or holder comprises a C-shaped holding part with holding elements for engaging the component, which holding part is movable along an arched guide means.

6. The lifting apparatus according to claim 5, wherein the holding part is guided on rollers or slide elements arranged in or along the guide means or guide).

7. The lifting apparatus according to claim 2, wherein the or each holding means or holder is movable by at least one controllable actuator.

8. The lifting apparatus according to claim 7, wherein the actuator is or comprises a hydraulic or pneumatic or electric cylinder, an electric motor or a spindle drive.

9. The lifting apparatus according to claim 7, wherein at least one control device is provided for controlling the movement of the at least one holding means or holder.

10. The lifting apparatus according to claim 9, wherein at least one sensor means or sensor for sensing a given or upcoming vertical tilting of the lifting apparatus or of the frame or of at least one support arm is provided, whereby the control device is adapted to control the pitching system depending on the sensor means or sensor information.

11. The lifting apparatus according to claim 1, wherein pitching system respectively the holding means or holder is adapted to rotate the component over an angle of at least 20°, of at least 40° and or over a maximum angle of 90°.

12. A crane comprising a lifting means or lift with a lifting apparatus according to claim 1.

13. The crane according to claim 12, wherein the lifting means or lift comprises one or more lifting cables, to which a connection device is attached, at which connection device the lifting apparatus is attached.

14. The crane according to claim 12, wherein one or more taglines are attached to the lifting apparatus.

15. A method for lifting a component comprising a non-circular cross section extending over the major part of its length, using a crane according to claim 12, wherein during the lifting process, when a vertical tilting movement of the lifting apparatus or at least the possibility of such a vertical tilting movement is detected, the pitching system is controlled for pitching the component around its longitudinal axis for counteracting the tilting movement.

16. The method according to claim 15, wherein during the lifting process the orientation of the lifting apparatus is constantly sensed by at least one sensor means or sensor of the lifting apparatus, whereby the pitching system is controlled by a control device based on the provided sensor means or sensor information.

17. The method according to claim 16, wherein the control device controls the movement of the at least one pivotable holding means or holder.

Description

BRIEF DESCRIPTION

[0024] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

[0025] FIG. 1 shows a principle sketch of a part of an inventive crane comprising an inventive lifting apparatus holding a rotor blade to be attached to a wind turbine;

[0026] FIG. 2 shows a side view of the lifting apparatus of FIG. 1 with a cut through the blade seen from the tip of the blade, with the blade being in a basic position;

[0027] FIG. 3 shows the arrangement of FIG. 2 with the blade being rotated in a clockwise direction by the pitching system; and

[0028] FIG. 4 shows the arrangement of FIG. 2 with the blade being rotated counterclockwise by the pitching system.

DETAILED DESCRIPTION

[0029] FIG. 1 shows a part of an inventive lifting crane 1 comprising a lifting device 2 with several cables 3, to which a connection device 4 is attached, as commonly known.

[0030] To the connection device 4 an inventive lifting apparatus 5, often also called yoke, is attached. The lifting apparatus 5 comprises, see also FIGS. 2 and 3, a frame 6 with two end-standing support arms 7, which here have a C-form.

[0031] A component, here a rotor blade 8, is carried by the lifting apparatus 6. The C-shaped support arms 7 are equipped with respective holding means or holder 9 for holding or gripping the rotor blade 8.

[0032] The rotor blade 8 is arranged in a horizontal direction and is lifted to be attached to a mounting interface 10 of a hub 11 of a wind turbine 12 shown in FIG. 1. It is therefore necessary to precisely position the blade root 13, which connects to the airfoil-shaped blade body 14, exactly relative to the mounting interface 10. This lifting and positioning is sometimes performed while wind blows and therefore interacts with the rotor blade 8 making the rotor blade 8 move.

[0033] The connection of the lifting apparatus 5 to the connection device 4 is not stiff. It is realized for example by a cable connection 15, which allows for the lifting apparatus 5 and therefore for the rotor blade 8 to rotate around a vertical axis. For stabilizing the lifting apparatus 5 respectively the blade 8 taglines 16 are attached to the lifting apparatus 5, by which a horizontal movement may be avoided or at least widely compensated.

[0034] The cable connection 15 does not only allow for a rotation around a vertical axis, but also for a tilting movement around a horizontal axis, which tilting movement is shown by the arrows P1. This tilting movement makes the lifting apparatus 5 tilt to the left or right side shown in FIG. 1, which tilting movement results in a respective movement of the rotor blade 8. Therefore, depending on the tilting to the left or to the right, the blade root 13 either performs a vertical movement upwards or downwards, as shown by the arrows P2 in FIG. 1. Therefore, its relative position to the mounting interface 10 may change due to such a vertical movement, which therefore needs to be counteracted.

[0035] For counteracting such a vertical movement, the lifting apparatus 5 comprises a pitching system 17, which is adapted to rotate the rotor blade 8 around its longitudinal axis respectively to change its spatial orientation, as shown in FIGS. 2-4.

[0036] As FIG. 2 shows in more detail, the rotor blade 8 is fixed in the holding means or holder 9. Each C-shaped arm 7 for example is equipped with a separate holding means or holder 9, which holding means or holder are part of the pitching system 17. The holding means or holder 9 comprises a holding part 18, which here has for example a C-shaped form, to which holding part 18 respective holding elements 19 like holding or clamping pads or the like are attached, which, as FIGS. 2-4 show, firmly fix the rotor blade 8. They are adapted to hold the blade 8 in a region with a non-circular cross-section, as clearly shown in the figures. The clamping mechanism of the holding means or holder shown in the figure is just an example. It may be realized in various ways, e.g. with clamping claws with at least one of the claws being movable from an open to a clamping position, or with a scissor-like moving means or mover for at least one of the clamps.

[0037] The holding means or holder 9 is rotatable around a rotation axis, which in general is a horizontal axis, which is parallel to a central axis of the frame respectively the lifting apparatus in general. For rotating the holding means or holder 9 it comprises respectively is arranged on an arched guide means or arched guide 20, here in form of a C-shaped guiderail or the like, along which it is movable respectively rotatable. The guide means or guide 20 is equipped with a number of rollers 21, on which the holding part 18 rolls and is guided, when it rotates around the rotation axis 22 of the holding means or holder 9 respectively the pitching system 17. The rollers 21 may be arranged along the whole path along which the holding part 18 moves, or only at some separate points along the path. Instead of rollers 21 also sliding elements building a slide bearing may be used.

[0038] For effecting this rotational movement, at least one actuator 23 is provided, whereby, as in this embodiment, two separate holding means or holder 9 are provided at each support arm 7, two respective actuators 23, one for each holding means or holder 9, are provided, which are synchronized, in order to realize a synchronized movement of the holding part 18. An actuator 23 may for example be a hydraulic or pneumatic or electric cylinder, which can be changed in its length and which is with one end coupled to, for example, the support arm 7, while the other end is coupled to the holding part 18 or the like. Certainly, the actuator 23 may also be an electric motor which is mechanically coupled for example by a spindle drive or a toothed connection to the holding part 18 etc. Any actuator is suitable, as long as it is able to initiate a circular or rotating movement of the holding part 18 and with it of the blade 8 along the guide means or guide 20.

[0039] For controlling the actuator 23 a control device 24 is provided, which controls the one or both actuators 23 in order to adjust the spatial orientation of the blade 8 by pitching it. The control device 24 communicates with the respective actuator 23, and also with at least one or more, sensor means or sensor 25, which is adapted to sense the spatial orientation of the lifting apparatus 5 respectively the frame 6 especially in regard of the vertical orientation respectively a vertical movement, which orientation or movement is an indicator of the vertical position or movement of the root 13 which needs to be aligned with the mounting interface 10. This sensor means or sensor 25 may for example be a position sensor or an acceleration sensor or the like. Besides the fully automatic control also a partly automatic control is possible, e.g. with a sensor means or sensor sensing a movement of the lifting apparatus and a manual control of the actuators based on the sensor information or the like.

[0040] The control device 24 is adapted to analyze the sensor means or sensor information in order to determine whether an unwanted vertical movement of the lifting apparatus 5 and therefore of the root 13 is likely to happen or is already given, and which measures need to be taken in order to counter this unwanted movement. So, the control device 24 may, due to the constant monitoring of the spatial situation by the one or the several sensor means or sensor 25, immediately respond to any relevant information from the constantly monitoring sensor means or sensor 25 in order to immediately control or provide a respective counteraction by controlling the actuators 23 and therefore by controlling the pitching system 17 in order to rotate the blade 8 in a clockwise direction (see arrow P3) or in a counterclockwise direction (see arrow P4). The control device is adapted to determine the direction of rotation based on the information regarding the direction of the possible or given movement and the known orientation of the blade 8 fixed in the holding means or holder 9, respectively its airfoiled surfaces.

[0041] FIG. 2 shows the arrangement of the blade 8 in the position, in which it is fixed or gripped by the holding means or holder 9 for the first time on the ground in order to be lifted to the hub. In this position, the holding parts 18 of both holding means or holder 9 are arranged in a basic position or an intermediate position, from which in both clockwise and counterclockwise directions for example the same angle of rotation may be run. If now the blade 8 is lifted, it is in the basic horizontal position.

[0042] When now wind blows, the wind may interact with the blade 8 and flow around the upper surface 26 and the lower surface 27 of the blade 8, which surfaces 26, 27 have different shapes due to the non-circular cross-section of the blade 8, as clearly shown in FIGS. 2-4. This leads to different wind speeds on the upper and lower surface side, as the upper surface 26 and the lower surface 27 have different lengths, along which the wind flows. As commonly known, a pressure difference results, which may generate a certain suction or drag in the vertical direction, making the blade move downwards or upwards, and therefore also making the root 13 move downwards or upwards, as the blade 8 and therefore the lifting apparatus 5 are movable around the horizontal axis of the cable connection 15, as already mentioned.

[0043] In order to counteract or compensate this unwanted vertical movement, it is possible by controlling the pitching system 17 to rotate the rotor blade 8 around the longitudinal axis 22 either in a clockwise direction (arrow P3) or in a counterclockwise direction (arrow P4), with the basic position of FIG. 2 as a starting point. This rotational movement is controlled by the control device 24, which is adapted to calculate the necessary angle of rotation in order to change the spatial orientation of the blade 8 respectively its upper and lower surface 26, 27 in a way sufficient to compensate or counteract the vertical tilt respectively the pressure difference which is the cause for the unwanted vertical tilt.

[0044] FIG. 3 shows an example, where the control device 24 controls the pitching system 17 to rotate in the clockwise direction according to arrow P3. It controls the actuators 23 to move the holding part 18 along the arched guide means or guide 20, which movement is guided by the rollers 21 allowing for a very soft but stable movement. This rotates the holding means or holder 9 around the horizontal rotation axis 22, and with it also the blade 8 is rotated around its longitudinal axis changing its spatial position as clearly shown in FIG. 3. Again, the axis of rotation 22 must not be the longitudinal axis of the blade 8, but the blade 8 is pivoted around its longitudinal axis by rotating the holding means or holder 9 around its rotation axis 22. FIG. 3 shows that the upper surface 26 has another orientation relative to the blowing wind, which blows in this example from the left side as shown by arrow P5, as in the basic position according to FIG. 2. The same is true for the lower surface 27. By changing this spatial orientation, the aerodynamic situation is severely changed, as the surface lengths, along which the wind flows along the upper and lower surfaces 26, 27, changes. Resulting from this, also the pressure difference between the upper and the lower side changes, and with it the given suction or drag, which is the reason for the unwanted vertical movement. This movement therefore is counteracted and compensated.

[0045] As the control device 24 is adapted to calculate the necessary pitching angle, a very precise counteraction or compensation is possible. It is to be noted, that any rotational position between the basic starting position and the maximum rotational position in the clockwise or counterclockwise direction may be controlled in order to mostly or completely compensate the unwanted vertical movement, and in order to avoid any overcompensation. It is possible that a calculation means respectively the control device itself calculates or simulates the effect of various pitching movements or angles at the given wind direction and wind speed on the component respectively the blade to model how it reacts. The control device can then choose the most promising pitching angle and pitching direction based on this input.

[0046] FIG. 4 shows an example, in which the pitching system 17 is controlled by the control device 24 for a movement of the holding part 18 in the counterclockwise direction according to arrow P4. As shown, the position of the holding part 18 relative to the guiding means or guide 20 has again changed compared to the basic situation, as the holding part 18 is moved along the arched guide means or guide 20 by controlling the actuators 23. As shown in FIG. 4, the upper surface 26 and the lower surface 27 again have a very different spatial orientation relative to the blowing wind respectively the wind direction (arrow P5), compared to the basic situation of FIG. 2 or to the situation of FIG. 3. Again, the aerodynamic situation changes severely resulting in a remarkable change of the pressure difference between the upper and the lower blade side and therefore the suction or drag resting on the blade 8. Again, this allows for a compensation of the unwanted tilt movement in this specific situation.

[0047] It is to be noted, that FIGS. 2-4 are only principle sketches especially with regard to the shown wind direction according to arrow P5. This arrow is only shown in order to demonstrate the change of the spatial orientation of the upper and the lower surface 26, 27, relative to a wind direction. It is no indication that the blade 8 needs to be rotated or positioned according to FIG. 3, when the wind blows from this direction, or needs to be positioned according to FIG. 4 in this wind direction situation. The direction and the angle of rotation is solely determined by the control device 24 based on the sensor means or sensor information.

[0048] The pitch or rotation angle may in total be for example 20°, with an angle of +−10° starting from the basic position according to FIG. 2. It may certainly also be a larger angle, for example a total angle of 40° with a respective pitching angle of +−20° starting from the basic position of FIG. 2. A maximum angle may for example be 90°, with a pitch angle of +−45° starting from the basic position of FIG. 2. As mentioned, any intermediate position may be controlled and fixed in order to compensate vertical tilt.

[0049] The inventive pitching system allows for a very variable change of the aerodynamic properties of the whole lifting arrangement respectively of the blade and therefore of the forces acting on the lifting apparatus 5 and therefore for a very variable, changeable interaction of the blade 8 with the wind in order to produce a defined counteracting tilt moment or tilt movement, which counteracts or compensates an unwanted tilt moment or tilt movement resulting from the interaction of the fast blowing wind with the airfoil-shaped rotor blade 8. The compensation or counteracting system, the pitching system 17, allows for the installation of such a rotor blade 8 also at weather conditions in which up to now such an installation was not possible due to the strongly blowing wind. Now, the installation may also be done at wind speeds of 16 m/s and higher, as the system allows for an excellent compensation of any unwanted vertical movement. Therefore, the weather window, in which the installation may be done is significantly widened. Furthermore, the inventive stabilization or compensation allows for a faster installation, as no time is needed for a cumbersome positioning or orientation of the rotor blade root 13 relative to the mounting interface 10, as no unwanted vertical movement occurs and as the horizontal movement can be countered by the taglines.

[0050] Finally, the inventive lifting apparatus respectively the crane with the inventive compensation or counteracting pitching system allows for installing even larger blades, which interact even more with the wind causing the previously mentioned problems with an unwanted vertical movement, as this movement can be compensated.

[0051] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0052] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.