Patent Application
20220056891
The invention relates to a maintenance enclosure for use when maintaining a wind turbine blade, wherein the maintenance enclosure comprises a ceiling, a floor and at least two side walls extending between the ceiling and the floor. The invention also relates to a method for maintaining a wind turbine blade.
Wind turbines have become an increasing source of energy around the world. These devices produce energy by having a set of blades rotate in the wind and thereby drive a generator which produces energy. It is known that especially the blades are subject to heavy wear due to the direct exposure to the environment and the high tangential velocity, especially at the tip of the blade. As the wind turbine blade rotates the leading edge of the blade may collide with e.g. rain drops. The angular speed and length of the wind turbine blade results in a high-energy impact between rain drops and the leading edge of the wind turbine blade whereby the rain drops may, over time, damage the blade of the wind turbine. Damage on the wind turbine blade may also origin from e.g. lightning strikes or fatigue loads which may result in crack propagation in the blade. This is not particularly beneficial as the aerodynamic behavior and the structural integrity of the blade is thereby negatively affected. Ultimately, the performance of the wind turbine is heavily reduced, or the wind turbine blade may even break down if no actions are taken.
Thus, from DE 10 2016 121 273 A1 it is known to perform service on wind turbine blades by lifting a maintenance chamber up to a vertically positioned wind turbine blade and therefrom perform the necessary service and maintenance work.
However, performing maintenance according to the prior art is difficult and complex in that only a limited part of the wind turbine blade may be accessed from the maintenance chamber. Thus, the maintenance chamber according to the prior art is not efficient for maintaining wind turbine blades.
It is therefore an object of the present invention to provide for an apparatus and method for maintaining wind turbine blades which solves the above-mentioned problems.
The invention provides for a maintenance enclosure for use when maintaining a wind turbine blade. The maintenance enclosure comprises a ceiling, a floor and at least two side walls which extend between the ceiling and the floor. The maintenance enclosure also comprises a first adjustable opening in a first side wall of the at least two side walls which are adapted for receiving the wind turbine blade and a second adjustable opening in a second side wall of the at least two side walls which are adapted for receiving the wind turbine blade. The first adjustable opening and the second adjustable opening are positioned opposite each other and the floor comprises a slit which extends at least a portion of the distance between the first adjustable opening and the second adjustable opening. Furthermore, the slit is adapted for receiving the wind turbine blade.
It is advantageous to provide for a maintenance enclosure which comprises a slit and adjustable openings in a first side wall and a second sidewall of the maintenance enclosure in that the maintenance enclosure may be placed on a wind turbine blade in a horizontal position. This is advantageous in that the maintenance work is easier to perform and a larger section of the wind turbine blade may be enclosed by the maintenance enclosure.
In this context, the term “maintenance enclosure” should be understood as any construction which is fully or partly enclosed. Thus, the maintenance enclosure could comprise a container, a steel frame, a booth or any other type of fully or partly closed construction which may be used for receiving and maintaining a wind turbine blade in a horizontal position.
Furthermore, in this context, the term “adjustable opening” and should be understood as an opening which adapts to the operational requirements, i.e. it may be closed, open, partly closed and/or adaptable to a shape of a wind turbine blade. Thus, it may be a hatch, door, hole or other kind of opening which may be re-shaped, closed, partly closed or opened.
In this context, the term “slit” should be understood as a channel or cut-away which extends completely through the floor in the vertical direction such that it forms an open channel extending at least a part of the distance between the first and second adjustable opening and whereby at least a part of the wind turbine blade may be received in the slit.
In an aspect of the invention the maintenance enclosure comprises a blade edge support adapted for supporting the maintenance enclosure on an edge of the wind turbine blade.
It is advantageous to provide the maintenance enclosure with a blade edge support in that the maintenance enclosure may be supported on the edge of the wind turbine airfoil such that the mutual engagement stabilizes the position of the enclosure and the airfoil or at least such that the maintenance enclosure follows the position of the wind turbine blade.
In this context, the term “blade edge” should be understood as the leading edge or the trailing edge of the wind turbine blade.
In this context, the term “blade edge support” should be understood as a rack, frame, chain, suspension or any other kind of structure which may support the maintenance enclosure on the leading edge of the wind turbine blade such that at least a part of the weight load from the maintenance enclosure is transferred through the wind turbine blade and/or such that the blade edge support may aid in maintaining the mutual position of the maintenance enclosure and the blade vertically but e.g. also horizontally.
In an aspect of the invention the maintenance enclosure is formed elongated and wherein the first side wall and the second side wall are positioned in opposite ends of the elongated maintenance enclosure.
It is advantageous to form the maintenance enclosure elongated and arranging the first and second side wall in opposite ends of the maintenance compartment in that it hereby is possible to form the maintenance enclosure relatively compact and still be able to access a relatively large portion of the blade from inside the maintenance enclosure. Thus, the maintenance enclosure can be formed with a simple geometry which is easy to lift onto the wind turbine blade.
In an aspect of the invention, the maintenance enclosure is formed as a parallelepiped, wherein each angle is a 90-degree angle.
Forming the enclosure is a parallelepiped with 90-degree angles is advantageous in that a rigid and safe enclosure is provided. Furthermore, this shape enables easy storing, stacking and handling.
It should be emphasized, that a parallelepiped with 90-degree angle is to be understood as a three-dimensional figure wherein the base shape as seen from the side (transverse to its longitudinal direction) has a rectangular shape.
In an aspect of the invention, the maintenance enclosure is an ISO-container comprising a corner casting in each corner of said ISO-container.
It is advantageous if the maintenance enclosure is an ISO-container comprising a corner casting in each corner in that the maintenance enclosure thereby comprises standardized dimensions such that standard container lifting and transportation machinery may be used for lifting and transporting the maintenance enclosure.
A corner casting is well known to the skilled person as the corner block provided at each corner of the ISO-container for lifting the container. Each of these corner castings are provided with a number of openings for twistlock fasteners to allow gripping the container from above, below, or the side, and enable mutual fixation between stacked containers to secure them during stacking.
In an aspect of the invention, the slit extends along the longitudinal direction of the maintenance enclosure.
Usually the length of the maintenance enclosure is larger than the width. Therefore, it is advantageous if the slit extends along the longitudinal direction of the maintenance enclosure in that the size of the enclosure is utilised more efficiently.
In an aspect of the invention, the slit extends the entire length of the floor.
It is advantageous if the slit extends the entire length of the floor in that the service enclosure may be lifted onto any part of the blade.
In an aspect of the invention, the first adjustable opening and/or the second adjustable opening comprises a sliding door.
It is advantageous to provide one or both of the adjustable openings with a sliding door in that it may easily be closed/open depending on requirements. Furthermore, sliding door do not swing open due to e.g. wind load and they do not require extra space when opened.
In an aspect of the invention, the maintenance enclosure comprises blade positioning means adapted for maintaining the mutual position between the maintenance enclosure and the wind turbine blade in the horizontal direction.
To efficiently harvest energy from wind, wind turbines are designed as tall constructions such that the blades may rotate at a high altitude where a strong wind exists. However, same wind may also introduce large blade tip deflections which may constitute a problem when lifting the maintenance cabin onto the blade. Therefore, it is advantageous to provide the maintenance cabin with blade positioning means for maintaining the mutual position between the maintenance cabin and the blade in the horizontal direction in that the maintenance cabin and the blade are mutually engaged whereby the working environment is stabilised.
In an aspect of the invention, the blade positioning means are adjustable in the horizontal direction.
It is advantageous if the blade positioning means are adjustable in the horizontal direction in that the blade positioning means hereby can be adapted to the actual width of the blade. Furthermore, the blade positioning means may be used for gripping onto the wind turbine blade and thereby stabilise the horizontal position of the maintenance enclosure and the blade.
In an aspect of the invention, the blade positioning means comprises suction cups and/or expanding walls.
To ensure that any part of the blade may fit into the slit the slit is designed wider than the blade by a margin such that there is some tolerance on either side of the blade. However, this also enables the blade to deflect back and forth and it is therefore advantageous if the blade positioning means comprises expanding walls for obtaining a tight sealing along the enclosure 1 and the blade 2. It is also advantageous if the blade positioning means comprises suction cups in that the suction cups may engage the surface of the blade 2 such that the mutual position between the blade 2 and enclosure 1 is stabilized.
In this context, the term “expanding walls” should be understood as a movable wall, expanding air cushion, barrier or any other kind of wall which may expand.
In an aspect of the invention, the maintenance enclosure comprises lifting lugs on the outer side.
It is advantageous to provide the maintenance enclosure with lifting lugs in that the maintenance enclosure may be lifted up by lifting from the dedicated lifting lugs whereby the stresses in the construction arising when lifting the enclosure are well distributed.
In an aspect of the invention, the first adjustable opening and/or the second adjustable opening comprises a sealing element adaptable to the shape of at least a part of the circumference of the wind turbine blade.
It is advantageous if the first adjustable opening and/or the second adjustable opening comprises a sealing element which is adaptable to the shape of at least a part of the wind turbine blade in that a tight sealing may be achieved on different sections of the blade which may comprise a different shape. Furthermore, this is advantageous in that e.g. rain, snow or dust is kept outside whereby a comfortable working environment may be obtained.
It should be emphasized that the sealing element could provide for sealing against rain, snow, wind, thermal insulation or other type of sealing.
In an aspect of the invention, the sealing element comprises air cushions.
It is advantageous if the sealing element comprises air cushions in that the sealing element may easily adapt to the blade contour and thereby provide for a sufficient sealing and a gentle contact between sealing and wind turbine blade.
In an aspect of the invention, the length of the maintenance enclosure is between 4 and 30 meters, preferably between 6 and 22 meters and most preferably between 8 and 16 meters. The width of the maintenance enclosure is between 1 and 10 meters, preferably between 2 and 8 meters and most preferably between 3 and 6 meters. The the height of the maintenance enclosure is between 0.5 and 8 meters, preferably between 1 and 6 meters and most preferably between 2 and 5 meters.
If the length, width and height of the maintenance enclosure is too large, the maintenance enclosure may become too heavy and unpractical to move around.
Furthermore, if for example the length is much larger than the width or the height, the stiffness of the construction may be insufficient, and the enclosure may buckle under its own weight or when carrying loads. And if the dimensions are too small, it may be troublesome to fit working tools and maintenance personnel inside the enclosure. Thus, the present dimensions present an advantageous relationship between structural integrity and function.
In an aspect of the invention, the maintenance enclosure comprises positioning means for bringing the maintenance enclosure into alignment with the wind turbine blade.
It is advantageous to provide the maintenance enclosure with positioning means in that the orientation and position of the maintenance enclosure may be adjusted while mid-air for easier alignment with the wind turbine blade.
In this context, the term “positioning means” should be understood as propellers, nozzles, wires or other kind of position actuators suitable for adjusting the position of the maintenance enclosure when mid-air.
In an aspect of the invention, the positioning means comprises propellers.
It is advantageous if the positioning means comprises propellers in that the orientation of the maintenance enclosure may be adjusted with a relatively simple mechanical solution and that the adjustment of the position and/or the orientation of such a maintenance cabin may be performed without the aid from a crane, wind turbine tower, ground tools or other.
In an aspect of the invention, the maintenance enclosure comprises guide means at the floor which are arranged to guide the wind turbine blade into the slit.
It is advantageous if the service enclosure comprises guide means at the floor in that the blade is easier guided into the slit of the service enclosure.
In this context, the term “guide means” should be understood as a guide wheel, a narrowing-down channel, air cushion or other type of guider for easier guiding the blade into the slit.
In an aspect of the invention, the maintenance enclosure comprises lifting means inside the maintenance enclosure.
It is advantageous to provide the maintenance enclosure with lifting means inside the enclosure in that heavy tools (which may be necessary in connection with the maintenance of the blade) may easier be lifted and moved inside the enclosure.
In this context, the term “lifting means” should be understood as a traverse crane, hydraulic jack, pulley system or other kinds of lifters for lifting heavy tools or other objects inside of the maintenance enclosure
Furthermore, the invention provides for a method for maintaining a wind turbine blade. The method comprising the steps of:
It is advantageous to provide for a method for maintaining a wind turbine blade according to the above-mentioned method in that it is possible to cover a larger section of the blade at a time whereby the maintenance enclosure is more efficient. Furthermore, the service personnel may perform the maintenance work in a more comfortable working position in that the workers do not have to repeatedly bend and stretch as would have been necessary in order to work along a blade in a vertical position. Also, space problems in relation to the wind turbine tower are solved in that the maintenance enclosure is operated in an area away from the tower.
In an aspect of the invention, the method comprises the step of fixating the position of the maintenance enclosure in relation to the wind turbine blade before performing the maintenance.
When the blade is received in the maintenance enclosure it may fluctuate from side to side and lead to a potentially lethal situation for the maintenance personnel inside of the enclosure. Therefore, it is advantageous to fixate the position of the enclosure in relation to the blade before performing the maintenance in that a safer working environment is achieved. Furthermore, the maintenance work itself is easier to carry out if the wind turbine blade is not fluctuating inside the enclosure.
In an aspect of the invention, the wind turbine blade is positioned with a leading edge of the wind turbine blade facing upwards.
The leading edge of the blade is exposed to heavy wear and a large part of the maintenance work is performed hereon. Therefore, it is advantageous to arrange the blade such that the leading edge is facing upwards in that the leading edge is easier accessed. Furthermore, the blade is designed to carry a much greater load in the direction from the leading edge to the trailing edge than in the opposite direction in that the blade is loaded in this direction during normal use.
In an aspect of the invention, the maintenance enclosure is lifted onto the wind turbine blade by means of a crane.
It is advantageous to use a crane for lifting the maintenance cabin onto the wind turbine airfoil in that it provides for a stable and balanced lifting.
It should be emphasized that in this context, the term “crane” should be understood as any type of tower crane, telescopic crane, floating crane or other type of crane suitable for the task of lifting heavy objects.
In an aspect of the invention, the method further comprises the step of guiding the maintenance enclosure onto the wind turbine blade by means of positioning means capable of adjusting the position and/or orientation of the maintenance enclosure in the horizontal plane.
Joining two objects in a certain orientation mid-air may be difficult for example if the wind is blowing. Therefore, using positioning means capable of adjusting the position and/or the orientation of the enclosure is advantageous in that the step of guiding the maintenance enclosure onto the blade is eased.
In an aspect of the invention, the method further comprises the step of sealing a gap between the wind turbine blade and the floor and/or between the wind turbine blade and the at least one sidewall after lifting a maintenance enclosure onto the wind turbine blade.
It is advantageous to seal a gap between the wind turbine blade and the floor and/or between the blade and the at least one sidewall in that a more comfortable working environment is achieved in that the enclosure is isolated from rain, snow, wind.
In an aspect of the invention, the method of maintaining the wind turbine blade is performed by means of a maintenance enclosure according to any of the previously described maintenance enclosures.
Using the previously described maintenance enclosures for carrying out the method of maintaining the wind turbine blade is advantageous in that it provides for an efficient maintenance and comfortable working environment.
The invention also provides for use of a maintenance enclosure according to any of the previously described maintenance enclosures for performing maintenance on a wind turbine blade of an offshore wind turbine.
Offshore wind turbines are located at sites with tough weather conditions. Therefore, using a maintenance according to any of the previously described maintenance enclosures for maintaining a wind turbine blade of an offshore wind turbine is advantageous in that it is be easily adapted to these conditions.
The invention will be described in the following with reference to the figures in which
It should be noted that the wind turbine blade 2 is mounted on a wind turbine throughout all the figures although this is not shown in the figures for the sake of simplicity. Furthermore, it should be noted that orientation terms such as, horizontal, vertical, up and down should be understood in relation to the maintenance enclosure in operational position, i.e. when the floor 4 of the maintenance enclosure 2 is substantially parallel with a wind turbine blade 2 in horizontal position or close to horizontal position when mounted on a wind turbine.
At some point in the lifetime of the wind turbine blade 2, maintenance must be performed due to e.g. cracks initiating from fatigue loads and the wear on the leading edge 10 of the wind turbine blade 2 due to collision with e.g. rain drops. The maintenance enclosure 1 as disclosed in
The maintenance personnel may be present inside the maintenance enclosure 1 during the process of lifting the maintenance enclosure 1 up and onto the wind turbine blade 2. They may also be transported to and from the maintenance enclosure e.g. with a helicopter or other means for transporting people after the maintenance enclosure 1 has been positioned on the blade 2.
In this embodiment the maintenance enclosure 1 is lifted onto the wind turbine blade 2 by means of a telescopic crane (not shown). However, in another embodiment, the maintenance enclosure 1 could be lifted by using a helicopter, one or more drones, a forklift machine, a mobile crane, crawler crane or any other means for lifting the maintenance platform onto the wind turbine airfoil. The maintenance platform 1 may also be self-propelled e.g. by comprising nozzles or propellers at the bottom (or at the top) which lift the maintenance platform 2 upwards.
When the maintenance enclosure 1 must be repositioned in order to perform maintenance work or service on another section of the wind turbine blade 2, the repositioning is performed by e.g. a crane (not shown) which lifts the maintenance enclosure 1 free from the blade 2 where after it is moved along the blade. However, in an embodiment the maintenance enclosure 1 may comprise driving means (not shown) for moving the maintenance enclosure 1 along the blade 2 without the aid of a lifting crane such that it is self-propelled. The driving means could comprise wheels, a pulley system, caterpillar tracks or any other kind of driver suitable for moving the maintenance enclosure 1 along the blade 2.
In this embodiment, the first side wall 5a and second side wall 5b comprises a series of struts. However, in another embodiment, the first side wall 5a and/or the second sidewall 5b could comprise a solid wall (see for example
In an embodiment, the maintenance enclosure may be completely or partly enclosed by a tarp and it could be open to the sides and/or the top and/or it could be partly open to the sides and/or the ceiling.
As an exemplary embodiment the maintenance work could be performed according to the method comprising the steps of
Some maintenance work may only require service or maintenance on the tip of the wind turbine blade 2. Therefore, the maintenance enclosure only encloses the tip of the wind turbine blade 2 (see for example
In this embodiment, the blade edge support 9 is a rack shaped in the form of a “V”. However, in another embodiment the blade edge support 9 could comprise a frame, rods, beams, spring suspension or other kind of structure for supporting a part of the load from the main enclosure 2 on the leading edge 10 of the blade 2.
Also, some maintenance work may require drilling, welding, gluing, soldering or other kind of process which may develop toxic smoke or fumes which may be harmful to the maintenance personnel if exposed to for large periods of time. Therefore, the maintenance enclosure 1 may comprise a ventilation system 26. The maintenance enclosure 1 may further comprise a climate control system or a dehumidifier for adjusting the environment inside the maintenance enclosure 1. Said systems could be separate systems or combined into one system.
The maintenance enclosure 1 may be provided with different kinds of monitoring systems. For example, the maintenance enclosure 1 may be provided with anemometers for monitoring wind speeds and thereby provide the maintenance personnel with warning signs if the wind speed exceeds a critical speed at which it may not be safe to stay in the maintenance enclosure 1. Also, in such situations, a quick evacuation route may be urgent. Thus, in an embodiment, the maintenance enclosure 1 may comprise means for evacuating the personnel such as inflatable evacuation slide, evacuation capsule, inflatable evacuation channel or other kind of evacuation systems. Other emergency equipment which may be comprised in the maintenance enclosure could be fire extinguishers, first aid kit and other.
Generally, the maintenance enclosure 1 may comprise different kind of tools necessary for performing the maintenance work such as compressors, drills, screw drivers, high pressure cleaners, tools boxes etc.
Maintenance work on a wind turbine blade 2 may require heavy duty tools, power tools, heavy replacement parts or other objects, which may be troublesome to move around. Thus, the maintenance enclosure 1 may comprise lifting means 21 for lifting these objects. In this embodiment, the lifting means 21 is a traverse crane. However, in another embodiment, the lifting means 21 could be a pulley system, a robot arm, boom arm or other kind of lifting structure which may be attached to the ceiling 3.
In this embodiment, the slit 8, as shown in
The maintenance enclosure 1 may comprise guide means 20 for directing and guiding the blade 2 into the slit 8 such that blade 2 is partly or fully received in the slit 8. In this embodiment, the guide means 20 comprises wheels. In another embodiment the guide means 20 could also comprise a suspension mechanism for absorbing any minor collision between the guide means 20 and the wind turbine blade 2 which may occur when the enclosure 1 is lifted onto the wind turbine blade 2. In another embodiment, the guide means 20 could comprise a narrowing-down channel and the edge of the floor could also be tapered so that the blade is guided into the slit 8.
In an embodiment, the maintenance enclosure 1 may comprise a battery pack (not shown) for providing energy to computer systems, tools, ventilation system or other energy consuming apparatus in the maintenance enclosure 1.
To ensure light-weight construction, the maintenance enclosure 1 comprises steel or aluminum frame. However, in an embodiment the frame could comprise e.g. composite materials or polymer materials. The main frame of the maintenance enclosure 1 could also comprise 3D printed parts.
In the embodiment as disclosed in
In this embodiment, the first side wall 5a and second side wall 5b are straight walls. However, in another embodiment, the sidewalls could be bent, curved, wave-shaped or any other shape which may be structurally or aerodynamically optimized for preventing buckling of the maintenance enclosure or for withstanding wind loads.
In this embodiment, the sealing element 16 comprises an air cushion 17. However, in another embodiment, the sealing element 16 could comprise a gate of brushes as known from door seals, a rubber seal, a wedge-shaped polymer seal, a pad or any other kind of seal which is adaptable to a part of the circumference of the wind turbine blade and which provides for a sealing effect. The air cushion 17 may provide for a sealing element 16 for providing a firm seal between the wind turbine blade 2 and the first wall 5a of maintenance enclosure 1 such that the maintenance enclosure 1 and the wind turbine blade 2 are firmly secured in relation to each other. The sealing element 16 may also provide for sealing against e.g. wind, rain, snow and dust which may leak into the maintenance enclosure 1 and affect the working environment or function of the maintenance enclosure 1.
The leading edge 10 of the blade 2 is exposed to heavy wear. Therefore, the main part of the maintenance work is performed on this region of the wind turbine blade 2 and the figures therefore illustrate maintenance enclosure 1 which encloses a wind turbine blade 2 with the leading 10 facing upwards. However, the maintenance enclosure 1 may also be lifted onto the blade with the trailing edge 27 facing upwards. Thus, the maintenance enclosure is also suitable for performing maintenance on the wind turbine blade 2 with the trailing edge 27 pointing upwards.
In this embodiment, the slit 8 extends in the entire longitudinal direction of the maintenance enclosure 1. However, in another embodiment, the slit 8 could extend in an angled direction or transverse direction. Also, in an embodiment, the slit 8 extends only a part of the length of the floor 4 e.g. if the maintenance enclosure 1 was initially placed vertically down onto the tip of the blade 2 and subsequently moved horizontally along the blade 2.
The maintenance platform may be used for offshore wind turbines as well as onshore wind turbines and depending on the site, wind currents may shift and rotate the maintenance platform 1 in the air as it is lifted onto the wind turbine blade 2. Therefore, in an embodiment (as disclosed in
Due to the design of the maintenance enclosure 1 it may operate at any given time of the day or year. However, it may often be used in daylight rather than in times of dark. Therefore, the maintenance enclosure may be provided with window panes 23 for increasing the natural light inside the maintenance enclosure and also for reducing the energy which is spent on artificial lightning. To further increase the efficiency of the maintenance enclosure 1, it may be advantageous to provide solar cells 22 on the ceiling 3 such that the maintenance enclosure 1 may be self-sustained (or at least more).
In this embodiment, the maintenance enclosure 1 is elongated and rectangular with 90-degree angles. However, in another embodiment, the maintenance enclosure may be triangular, circular, polygonal, parallelepiped with angles other than 90-degree or any other shape.
In this embodiment, the maintenance enclosure 1 may be an ISO-container with standard dimensions comprising corner castings in each corner. If the maintenance enclosure 1 is an ISO-container it may be easier to stack and ship the enclosure(s) to different sites by using standard container ships. In another embodiment the maintenance enclosure 1 may also comprise an ISO-container with lifting lugs 15 as shown in
Also, in the embodiment of
Although it is safest to suspend the maintenance enclosure 1 on a lifting crane at all times, the maintenance enclosure 1 may, in an embodiment, be supported entirely by the wind turbine blade 2.
The airfoil 2 is shaped such that it generates a pressure difference between the high-pressure side 25 and the low-pressure side 24 when the air flows from the leading edge 10 to the trailing edge 27 whereby an aerodynamic force is produced which generates lift.
The wind turbine 28 could be an offshore wind turbine or an onshore wind turbine on which wind turbine blades 2 may be serviced by using the maintenance enclosure 1 according to an embodiment of the invention.
The invention has been exemplified above with reference to specific examples of blade edge support 9, blade positioning means 12, sealing element 16 and other. However, it should be understood that the invention is not limited to the particular examples described above but may be designed and altered in a multitude of varieties within the scope of the invention as specified in the claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DK2019/050040 | 1/31/2019 | WO | 00 |
