SURFACE

The present invention relates to a system for mounting a lightning receptor to a surface.

It is general practice to protect rotor blades of wind turbines from strokes of lightning by integrating lightning receptors of an electrically conductive material in the blade surface. The lightning receptors are connected by lightning conductor cables extending through the interior of the rotor blade to a ground in the tower of the wind turbine.

Typically lightning spots of copper are implemented during the blade production process, for example a Resin Infusion Moulding (RIM) process.

Due to their large dimensions and their location in open areas wind turbines are frequently hit by lightning. Consequently lightning receptors often become damaged and repair or replacement is required. Repair requires bonding techniques whereas replacement requires both grinding and bonding techniques. Both involve labour intensive, time consuming and furthermore hazardous work that needs to be performed at high altitudes at remote locations. In addition thereto economic losses occur due to stand still of the wind turbine during repair and/or replacement.

The invention has for its object to provide a system and method for mounting a lightning receptor to a surface that lift these drawbacks.

This object is achieved by the system according to the invention which system comprises a first mounting element having an inner side and an outer side and a second mounting element, which system is arranged such that the first mounting element on the inner side can receive the second mounting element and on the outer side can receive the lightning receptor, wherein the system comprises first coupling means for detachably coupling the second mounting element to the first mounting element and second coupling means for detachably coupling the lightning receptor to the second mounting element such that the lightning receptor in assembled state of the system can be decoupled from both sides of the first mounting element.

The system according to the invention allows for non-destructive replacement of lightning receptors simply by decoupling the first and second mounting elements and removing a non-functioning lightning receptor from the system and replacing it with a new one. The work can be performed quickly without the need for heavy equipment or complex bonding techniques. Advantageously the system according to the invention allows the lightning receptor to be removed from the outside as well as from the inside of the rotor blade. Clearly performing work inside the rotor blade is much safer than on the outside.

In a first practical embodiment the first mounting element is arranged to allow passage of the lightning receptor through the first mounting element in a decoupled position of the second mounting element.

According to a robust, reliable and elegant embodiment the second mounting element is arranged to block the through passage of the lightning receptor at the inner side of the first mounting element in an assembled state of the system.

According to a practical embodiment the second mounting element is provided with a collar that is arranged to lie against the inner side of the first mounting element in an assembled state of the system. Preferably the first coupling means are arranged to detachably couple the collar to the first mounting element.

According to a further practical embodiment the second mounting element comprises a neck part arranged to be received by the first mounting element, said neck part having an outer edge arranged to lie near the outer side of the first mounting element in an assembled state of the system, wherein the second coupling means are arranged to detachably couple the lightning receptor to the outer edge.

In a complete embodiment that is ready for use the system comprises a lightning receptor. According to a preferred embodiment the lighting receptor is arranged to be received by the first mounting element, said lighting receptor having a bottom surface arranged to lie near the outer side of the first mounting element in an assembled state of the system. In an elegant preferred embodiment the lighting receptor is generally cylindrical.

In a further preferred embodiment the second mounting element is generally plate-shaped and is arranged to lie against the inner side of the first mounting element in an assembled state of the system.

The second coupling means comprise a pin-hole coupling, preferably a screw-threaded pin-hole coupling. Alternatively the second coupling means comprise mating screw thread on the contacting surfaces of the lightning receptor and the first mounting element arranged such that in assembled state the lightning receptor contacts the second mounting element.

The invention further relates to a method for mounting a lightning receptor to a surface of a rotor blade of a wind turbine by means of the system according to one or more of the preceding claims, comprising the steps of: Laying an outer surface layer of the rotor blade having a through hole therein;

Assembling the system by coupling the second mounting element to the first mounting element and by coupling the lightning receptor to the second mounting element;

Placing the system on the outer surface layer such that one part of the lightning receptor is positioned in the through hole;

Laying core material on the outer surface layer adjacent the system; and

- Laying an inner surface layer having a further through hole over the core material and the system such that the second mounting element and the lightning receptor may pass through the further through hole. The invention will be further described with reference to the attached drawings, wherein

Figure 1 shows a cross section through a first preferred embodiment of a system according to the invention mounted in a rotor blade;

Figure 2 shows the system of figure 1 in exploded view;

Figure 3 shows a cross section through a second preferred embodiment of a system according to the invention mounted in a rotor blade;

Figure 4 shows the system of figure 3 in exploded view;

Figure 5 shows a cross section through a third preferred embodiment of a system according to the invention mounted in a rotor blade;

Figure 6 shows the system of figure 5 in exploded view;

Figure 7 shows a cross section through a fourth preferred embodiment of a system according to the invention mounted in a rotor blade; and

Figure 8 shows the system of figure 7 in exploded view.

Like components are designated in the figures by means of the same reference numerals that are successively incremented by the number 100 for each successive preferred embodiment.

Figure 1 shows a first preferred embodiment of a system according to the invention in cross section. In figure 1 the system takes up the assembled state and is mounted in a surface, more particularly in a rotor blade of a wind turbine. Part of the rotor blade is visible comprising an outer shell 40 and an inner shell 60 separated by core material 50.

The system comprises a first mounting element 10 and a second mounting element 20 that is detachably coupled to the first mounting element 10. A lightning receptor 30 is detachably coupled to the second mounting element 20.

Figure 2 shows the system of figure 1 in exploded view. First mounting element 10 has a first side, referred to herein as the inner side that is in use directed to the inner side 60 of the rotor blade. The first mounting element 10 further has a second side, that opposes the first side, which second side is referred to herein as the outer side and in an assembled state of the system is directed to the outer side 40 of the rotor blade. The first mounting element 10 may have any shape and is depicted here as a rectangle. Preferably the height of first mounting element 10 corresponds to the height of the adjacent core material layer 50. The first mounting element 10 is provided with a through hole 1 1 , that may be centrally located. The shape and size of the through hole 1 1 correspond to the shape and size of the second mounting element 20.

The second mounting element 20 comprises a hollow neck part 21 and a collar 22. The shape and size of the neck part 21 correspond to the shape and size of the through hole 1 1 of the first mounting element 10. The height of the first mounting element 10 and the second mounting element 20 are arranged such that in an assembled position, when the neck part 21 is received in the through hole 11 , the collar 22 lies against the inner side of the first mounting element 10 and the outer edge 23 of the neck part 21 lies near the outer side of the first mounting element 10. In this assembled state the total height of the first and second mounting elements corresponds to the general height of the core material layer 50.

In the first preferred embodiment shown the lightning receptor 30 comprises a plate 31 arranged to form a spot in the outer shell 40 of the rotor blade. A bar 32 is connected to the spot plate 31. The bar 32 is arranged to extend through the through hole of the first mounting element 10 and neck part 21 of the second mounting element 20. The shape and size of the spot plate 31 correspond to the shape and size of the through hole 1 1 of the first mounting element 10. More specifically the through hole 1 1 is arranged to allow passage of the lightning receptor 30 through the first mounting element 10 in a decoupled position of the second mounting element 20. In an assembled state of the system the second mounting element 20 is arranged to block the through passage at the inner side of the first mounting element 10 by the lightning receptor 30. The lightning receptor 30 is made of electrically conducting material, preferably copper.

First coupling means 71 are arranged to detachably couple the collar 22 to the inner side of the first mounting element 10. In the first preferred embodiment shown the first coupling means comprise bolts, collar 22 comprises mating holes 24 and first mounting element 10 comprises mating holes 12.

The second coupling means 72 are arranged to detachably couple the lightning receptor 30 to the second mounting element 20. In the first preferred embodiment shown the second coupling means comprise bolts 72, mating holes 33 in the spot plate 31 and mating holes in the outer edge 23.

Figure 3 shows a cross section through a second preferred embodiment of a system according to the invention mounted in a rotor blade and figure 4 shows the system of figure 3 in exploded view. All reference numerals of the second preferred embodiment have been incremented by 100 with respect to the first preferred embodiment.

The second embodiment differs over the first embodiment in that the bar 32 is omitted. Cabling 180 can be connected directly to the second mounting element 120 by means of first coupling means 171 .

Figure 5 shows a cross section through a third preferred embodiment of a system according to the invention mounted in a rotor blade and figure 6 shows the system of figure 5 in exploded view. All reference numerals of the third preferred embodiment have been incremented by 100 with respect to the second preferred embodiment.

Figure 7 shows a cross section through a fourth preferred embodiment of a system according to the invention mounted in a rotor blade and figure 8 shows the system of figure 7 in exploded view. All reference numerals of the fourth preferred embodiment have been incremented by 100 with respect to the third preferred embodiment.

The third and fourth embodiment differ over the first and second embodiment in that the shape and size of the through hole 21 1 , respectively 31 1 , correspond to the shape and size of the lightning receptor 230, respectively 330 and in that the second mounting element 220, 320 covers the through hole on the inner side.

Lightning receptor 230, 330 has a generally cylindrical shape. The bottom surface of the lightning receptor 230, 330 is arranged to form a spot in the outer shell 240, 340 of the rotor blade.

The second mounting element 220, 320 is generally plate shaped. Generally the dimensions of the through holes 241 , 341 respectively 211 , 31 1 can be kept smaller in diameter when compared to the first and second embodiment.

The height of the first mounting element 210, 310 and the lightning receptor 230, 330 are arranged such that in an assembled position, when the lightning receptor is received in the through hole 211 , 311 , the second mounting element 220, 320 lies against the inner side of the first mounting element 210, 310 and the bottom of the lightning receptor lies near the outer side of the first mounting element.

First coupling means 271 , 371 are arranged to detachably couple the second mounting element 220, 320 to the inner side of the first mounting element 210, 310. In the third and fourth preferred embodiments shown the first coupling means comprise bolts, the second mounting element 220, 320 comprises mating holes 224, 324 and the first mounting element 210, 310 comprises mating holes 212, 312.

The second coupling means are arranged to detachably couple the lightning receptor 230, 330 to the second mounting element 220, 230. In the third preferred embodiment the second coupling means are formed by pin 232 and mating hole 225. Preferably pin 232 and hole 225 comprise mating screw thread.

In the fourth preferred embodiment the second coupling means are formed by mating screw thread on the contacting surfaces of the first mounting element 310 and the lightning receptor 330. In the assembled state the top surface of the lightning receptor 330 contacts the second mounting element 320. Besides the screw thread on the outer circumference the lightning receptor 330 is on its top and/or bottom surface provided with recesses 335, 336, that are arranged to cooperate with an auxiliary tool (not shown) to screw the lightning receptor 330 into and out of the first mounting element 310.

In the first preferred embodiment known cabling 80 can be connected directly to the bar 32 of the lightning receptor 30 by means of first coupling means 73.

In the second, third and fourth preferred embodiment cabling 180, 280 respectively 380 can be connected directly to the second mounting element 120, 220 respectively 320 by means of the first coupling means 171 , 271 , respectively 371.

The system is suitable for mounting the lightning receptor 30 to the surface 40, 50, and 60 of a rotor blade of a wind turbine. A method for mounting comprises the following steps that refer to the first preferred embodiment.

In a first step an outer surface layer 40 of the rotor blade is laid. This may be part of a known lamination process, such as Resin Infusion Moulding. In the outer layer a through hole 41 is made. The through hole corresponds to the widest dimensions of the lightning receptor 30. In this first preferred embodiment the widest dimensions are determined by the diameter of the spot plate 31.

The system needs to be assembled by coupling second mounting element 20 to the first mounting element 10 and by coupling the lightning receptor 30 to the second mounting element 20.

The assembled system is placed on the outer layer 40, such that one part of the lightning receptor, in this example the spot plate 31 , is positioned in the through hole 41.

In the next step core material 50 is laid on the outer surface layer 40 such that room is reserved for the system, more specifically for the first mounting element 10. Preferably the core material layer is laid adjacent the system. Suitable core material is known in the art and comprises: PVC-foam, (balsa) wood, PET et cetera.

Finally an inner surface layer 60 of the rotor blade is laid, also provided with a further through hole 61 , over the core material layer 50 and the system. The shape and size of the further through hole 61 need to be chosen such that the second mounting element 20 may pass through the further through hole 61. Since the dimensions of the second mounting elements 20, in this example the dimensions of the collar 22, are greater than the dimensions of the lightning receptor 30, in this example the dimensions of the spot plate 31 , the through hole 61 will also allow passage of the lightning receptor 30.

Known cabling 80 can be used to connect the lightning receptor 30, for instance by means of bolts 73 and mating holes 34, to ground.

It will be evident for a person skilled in the art that the method according to the invention is also suitable for mounting the second, third and fourth preferred embodiment of the system according to the invention.

Preferably the first mounting element is made of a plastic material. In the first embodiment the second mounting element preferably also is made of a plastic material. Suitable plastic materials are known in the art. Some examples are HDPE, PA, PMMA, POM and PP. In all other embodiments the second mounting element needs to be electrically conducting. Some examples of suitable electrically conducting material include: copper, aluminum, titanium and (stainless) steel.

It is noted that the invention is not limited to the preferred embodiments described and shown herein. Especially all combinations of the preferred

embodiments shown are included. The invention therefore generally extends to any embodiment that falls within the scope of the appended claims as seen in the light of the foregoing description and drawings.