Apparatus and Method for Repairing Fibre-Composite Structures

Abstract

Repairs need to be carried out on various structures in outdoor climatic conditions, which may be in wind or rain. Such a structure may be a wind turbine blade (1). This limits the time when the repairs can be conducted while conditions are within the limits set for the process. The invention provides an enclosure (4) which can be sealed to the structure so that a repair can be conducted at any desired time. The enclosure is large enough to enclose a desired work area with the operator's hands and arms entering to carry out the work through hand and arm seals (6, 7).

Claims

1. An apparatus comprising a temporary enclosure for, in use, enclosing a work area of a structure in need of repair, whereby an operator outside of the enclosure can access the work area through one or more holes or sleeves or gloves in a wall of the enclosure, the enclosure comprising a transparent portion through which the operator can view the work area.

2. An apparatus according to claim 1 that is made of flexible or partially rigid or rigid material that can be assembled near to the work area, deployed on the work area and removed from the work area for reuse.

3. An apparatus according to claim 1 or 2 that incorporates partially rigid or rigid members such as battens, poles, tubes or rods to support its structure.

4. An apparatus according to claim 1, 2 or 3 that incorporates tensioned elements such as guy lines, cords, webbing, elastic cord or straps to support its structure.

5. An apparatus according to any preceding claim that is made partly or wholly from essentially transparent materials.

6. An apparatus according to any preceding claim, in which the enclosure is sealable around the work area, using a seal held in close proximity to a surface of the structure in need of repair, so as to maintain a controlled environment within the enclosure.

7. An apparatus according to claim 6 whereby the seal is achieved through vacuum or pressure or adhesion or tension.

8. An apparatus according to any preceding claim whereby the enclosure is couplable to a supply of air that is conditioned to maintain desired conditions within the enclosure, that may include temperature, humidity, dust filtering, and control of contaminants.

9. An apparatus according to claim 8 comprising a duct, tube or pipe for the supply of the air.

10. An apparatus according to claim 8 or 9 comprising a climatic control unit for providing the air, that is partly or wholly integrated with the enclosure whereby it comprises a part of the wall or structure of the enclosure or is within the enclosure.

11. An apparatus according to any preceding claim comprising an exhaust that allows air to be vented, preferably in a controlled manner.

12. An apparatus according to any preceding claim incorporating one or more sealable openings in a wall of the enclosure, comprising arm holes or sleeves or gloves, to enable the operator to conduct the work within the enclosure.

13. An apparatus according to any preceding claim incorporating a port through which tools, materials or other items to be used in the work can be passed into the enclosure and removed from the enclosure, the port preferably being openable and resealable or closable.

14. An apparatus according to claim 13 in which the port is partially flexible and is sealable using a zip fastener or hook-and-loop material such as Velcro or lacing or buttons or press studs or hook-and-eye closures or magnetic strips or similar means.

15. An apparatus according to any preceding claim comprising a power-access port for allowing access, in use, of a power supply such as a cable, pipe or transmission linkage whereby electrical or pneumatic or hydraulic or mechanical or thermal or other form of power can be made available within the enclosure; and whereby electronic instrumentation and signal cables can be linked.

16. An apparatus according to claim 15 in which the power-access port is partially flexible and is sealable around the power supply using a zip fastener or hook-and-loop material such as Velcro or lacing or buttons or press studs or hook-and-eye closures or magnetic strips or similar means.

17. An apparatus according to any preceding claim, incorporating a power supply outlet whereby electrical or pneumatic or hydraulic or mechanical or thermal or other form of power may be made available within the enclosure.

18. An apparatus according to any preceding claim, in which the enclosure incorporates lighting.

19. An apparatus according to any preceding claim incorporating sensors, instrumentation or monitoring equipment to monitor (locally or remotely) and optionally record the conditions and activity within and around the enclosure.

20. An apparatus according to any preceding claim, in which the enclosure is attachable to the structure in need of repair by a plurality of removable anchor means, such as suction cups.

21. An apparatus according to any preceding claim, in which the enclosure comprises a notch configured to enclose the leading edge, or the trailing edge, or another portion, of a wind turbine blade.

22. An apparatus according to any preceding claim, further comprising an awning usable in conjunction with or independently of the enclosure to provide shelter from the weather.

23. An apparatus according to claim 22 in which the awning is made of flexible or partially rigid or rigid material that can be assembled near to work area and deployed on the work area.

24. An apparatus according to claim 22 or 23 in which the awning incorporates rigid or partially rigid members such as battens, poles, tubes, rods, etc. to support its structure.

25. An apparatus according to any of claims 22 to 24 in which the awning incorporates tensioned elements such as guy lines, cords, webbing, straps, etc. to support its structure.

26. An apparatus according to any of claims 22 to 25 in which the awning incorporates a seal arrangement that can be held in close proximity to the work surface so as to prevent or reduce water from running down the surface into the work area.

27. An apparatus according to any preceding claim, in which the enclosure is flexible or partially flexible to adapt to different shapes of work surface, or different positions on a wind turbine blade, or different designs of wind turbine blade, or different work tasks.

28. An apparatus according to any preceding claim in which the enclosure is modular so that components of the enclosure can be assembled as required to enable it to be adapted to different shapes of work surface, or different positions on a wind turbine blade, or different designs of wind turbine blade, or different work tasks.

29. A method for repairing a structure comprising the steps of: enclosing a work area of the structure in need of repair within an enclosure as defined in any preceding claim; and accessing the work area by means of the one or more holes or sleeves or gloves in a wall of the enclosure, while viewing the work area through the transparent portion of the enclosure.

30. A method according to claim 29, further comprising the step of sealing an edge of the enclosure to a surface of the structure.

31. A method according to claim 29 or 30, further comprising the step of coupling the enclosure to a supply of air, the air preferably being conditioned for supply to the enclosure.

32. A method according to any of claims 29 to 31, further comprising passing tools, materials or other items into the enclosure through an openable and resealable port.

33. A method according to any of claims 29 to 32, further comprising coupling a power supply to the enclosure, by means of a power-access port of the enclosure.

34. An enclosure substantially as described herein, with reference to the accompanying drawings.

35. A method for operating an enclosure substantially as described herein, with reference to the accompanying drawings.

Description

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

[0055] Embodiments of the invention are illustrated in FIGS. 1 and 2, in side view and front view. Photographs of one embodiment are shown in FIGS. 3 and 4, in side view and front view. A detail of a vacuum seal used in one embodiment is illustrated in FIG. 5, in cross section.

[0056] FIG. 1 illustrates an embodiment of the invention in use to undertake a repair on a wind turbine blade, in side view;

[0057] FIG. 2 illustrates an embodiment of the invention in use to undertake a repair on a wind turbine blade, in front view;

[0058] FIG. 3 shows a side view of a first embodiment of the invention being demonstrated with an operator;

[0059] FIG. 4 shows a front view of the first embodiment of the invention shown in FIG. 3;

[0060] FIG. 5 is a cross-section of a vacuum seal;

[0061] FIG. 6 is a front view of a second embodiment of the invention;

[0062] FIG. 7 is an enlarged view of the second embodiment of the invention shown in FIG. 6;

[0063] FIG. 8 is a perspective view of a third embodiment of the invention; and

[0064] FIG. 9 is a cross section of the third embodiment of the invention shown in FIG. 8.

[0065] The temporary enclosure is deployed onto a structure such as a wind turbine blade 1 in FIGS. 1 and 2. The work area 2 may for example require repair or painting or inspection. The work area may be accessed from an access platform 3 which could for example be suspended from the structure or supported by a truck mounted system. The access platform may advantageously be a conventional access platform. No modification of such conventional apparatus may be required to operate with embodiments of the present invention. (The access platform 3 is represented diagrammatically in FIGS. 1 and 2, and cut away to allow clearer illustration of the enclosure.) The temporary enclosure 4 is of dimension about 1 m by 1 m, and about 0.5 m deep, and is set up to surround the work area 2. The perimeter of the enclosure 4 is held in close contact with the surface of the structure by means of seals 5, which may for example use vacuum, supplied by a vacuum pump (not shown) so that that they form a seal with the surface.

[0066] FIG. 5 illustrates a suitable vacuum seal, in cross-section. The seal is extruded, with this cross-section, from an elastomeric material such as silicone rubber. As shown in FIG. 5, the seal has a central circular portion containing a bore 13 that extends throughout the length of the seal. The central circular portion is sufficiently rigid that it maintains its shape when air is drawn out of the bore by a vacuum pump or suction pump (not shown) during operation. A row of holes 14 extends outwardly from the bore on one side of the central portion of the seal, opening towards the surface of the blade or other structure during use. Two flanges 12 extend from the central portion, one on each side of the row of holes, and press against the surface in use in order to prevent or reduce any flow of air between the seal and the surface. The width of the seal across the flanges is approximately 40 mm. The seal 5 also has a flange 15 extending from the central portion opposite to the row of holes, by which it is attached to the rest of the enclosure 4 by stitching or adhesive. The seal extends around the entire perimeter of the enclosure, and the bore is couplable by a suitable pipe or tube to a vacuum pump or suction pump (not shown). When the internal air pressure in the bore is reduced, atmospheric pressure thus causes the flanges 12 to make close contact with the surface, holding the seal against the surface.

[0067] The enclosure 4 has areas that are essentially transparent, enabling the operator to see the work area 2 from outside the enclosure 4. The operator is able to reach into the enclosure 4 and carry out repairs and other work on the work area 2 through arm holes fitted with sleeves 6 that are adjustable or elasticated to form close seals 7 around the operator's wrists or arms. A port 8 is provided to pass tools, materials and other items into the enclosure, resealable with a zip or similar closure system. A similar port could also facilitate a power supply to be provided within the enclosure if desired. A climate control box 9 conditions air for temperature, humidity and cleanliness and passes this into the enclosure 4 through a flexible duct 10.

[0068] FIGS. 6 and 7 illustrate a temporary enclosure 40 according to a second embodiment of the present invention. The enclosure of the second embodiment is substantially as the first embodiment described above in relation to FIGS. 1 to 4, except that the enclosure 40 of FIG. 6 does not comprise a vacuum seal around its perimeter. The enclosure 40 is securable to the surface of a structure such as a wind turbine blade 1 by four suction-cup devices 42. Each suction-cup device 42 is made up of two suction cups 44 connected together by a handle 46. Fabric loops on each corner of the enclosure 40 are attachable to the handles of the suction-cup devices 42 by karabiners 48. By adjusting the position at which the suction-cup devices are secured to the surface, the edges of the enclosure 40 can be tensioned so that the enclosure adopts its intended shape.

[0069] Strips of fabric webbing 50 are attached to the enclosure 40 around its perimeter. When the enclosure and the suction-cup devices 42 are secured to the surface of a structure, the tension along the edges of the enclosure urges the webbing 50 into contact with the surface so as to form a seal. The seal between the webbing and the surface prevents, or reduces, the passage into the enclosure of outside contaminants such as water, and restricts the passage of air in and out of the enclosure so that a controlled atmosphere can be maintained within the enclosure.

[0070] FIGS. 8 and 9 show a temporary enclosure 60 according to a third embodiment of the present invention. The enclosure 60 is substantially as described above in relation to FIGS. 6 and 7, except that it has been adapted for use on a leading edge of a wind turbine blade 1.

[0071] In order to make the enclosure 60 suitable for attachment to a leading edge of a wind turbine blade 1, an upper surface 62 and a lower surface 64 of the enclosure 60 are shaped to conform to the contours of the leading edge. That is, the upper and lower surfaces contain a U or V-shaped notch shaped to receive the leading edge of a turbine blade 1. This is different to the enclosures 4, 40 of the first and second embodiments, which have perimeters adapted to engage substantially flat, or slightly curved, surfaces. This notched shape advantageously allows the enclosure 60 to be secured to and enclose a work area on the leading edge of a turbine blade, which is the portion that most frequently requires repair.

[0072] In order to allow work to be carried out on both sides of the leading edge without repositioning the enclosure 60, the enclosure comprises four arm holes fitted with sleeves 6. This also advantageously allows two operators to carry out repairs and other work on the work area simultaneously.

[0073] By altering the shape of the notch in the upper and lower surfaces, or making the enclosure of a material sufficiently flexible to accommodate differently shaped blade edges, the enclosure 60 may be made suitable for enclosing the trailing edge of a wind turbine blade.

Further Embodiments and Features

[0074] During in situ repair or other work carried out on structures such as wind turbine blades, the working area is exposed to the weather and contamination. Exposure to conditions outside the use specification of repair processes or materials could limit the conditions in which the repair can be done or reduce the integrity of the repair. To provide protection, the enclosure and method of the invention provides a temporary shelter, or habitat, around the working area.

[0075] As listed below, embodiments of the invention may optionally incorporate a number of features in order to provide a controlled environment for repairs, in a glove bag type bubble enclosure, with an open face that is sealed against the blade, and around the leading or trailing edge of a blade if required.

[0076] A preferred embodiment of the glove bag enclosure is supplied with filtered heated air to maintain a desired environment within the enclosure, and optionally to maintain a positive pressure. It has sleeves for the technician's arms, a clear viewing panel, resealable access ports for tools and power cables, a horizontal bench surface and internal lighting for night working.

[0077] The structure will be lightweight, flexible, made mainly from fabric, could incorporate battens, poles or flexible hoops to maintain its shape (as with a tent), straps or cords to maintain tension and rubber seal section held against the blade. Access ports will be closed with zips or hook-and-loop fastener, or other resealable fastenings.

[0078] The enclosure can protect in situ repair work on a wind turbine blade from the weather and contamination.

[0079] The enclosure should maintain an internal environment with a temperature between 20 C. and 30 C., when the external ambient temperature may be between 5 C. to 30 C.

[0080] During curing of composite materials in the enclosure, the temperature of the composite workpiece should be maintained stable to within 3 C. No cooling function may be required, but thermostatic control with a temperature sensor inside the working area is advantageous.

[0081] The system should maintain an internal environment with relative humidity below 70% non-condensing. When it is raining or foggy, the relative humidity is close to 100%. Relative humidity in the enclosure may be reduced by heating the air or alternatively by using a dehumidifier (which condenses moisture out of the air which is recirculated) or a desiccant (which chemically absorbs moisture). If the surface temperature is higher than the external ambient temperature, moisture is unlikely to condense on the surface of the blade or structure.

[0082] The system should maintain an internal environment with a predetermined air cleanliness, optionally consistent with use of input air filters to BS EN779.1.

[0083] The ventilation system should preferably change the air within the internal environment of the enclosure at a predetermined rate, such as a predetermined number of times per hour.

[0084] For a given internal volume, say 1 m.sup.3, the air flow rate into the environment can be calculated from the air changes an hour. For example to achieve 60 changes per hour will require 60 m.sup.3/hour of air flow or greater than 1 m.sup.3/minute. The airflow will be reduced by any filter at the air input to the enclosure, perhaps by up to 30%, so the fan delivering the air must deliver sufficient extra capacity, at least 1.4 m.sup.3/min. This could advantageously be achieved by a 119 mm axial fan, for example.

[0085] The air flow rate then determines the power of any heater required to maintain the required internal temperature: power=mass flow ratespecific heat capacity of airtemperature rise.

[0086] The system should prevent dust contamination of the internal environment during repairs, e.g. by providing filtered air at positive pressure.

[0087] The system should prevent ingress of water into the internal environment during repairs. Rain may be blown by light wind (<10 m/s) and water will run down the surface of the blade or structure. In addition to a water resistant enclosure, rain water running down the surface of the blade or structure must be diverted away e.g. with contact seals such as vacuum seals, with particular attention to the seal between the habitat and the blade above the working area.

[0088] The materials used for the enclosure should be non-combustible or fire-retardant.

[0089] The internal air in the enclosure is preferably vented and dispersed safely away from the operator.

[0090] The enclosure should provide shading from direct sunlight.

[0091] Ideally the system should be usable without limitations or causing concern in wind speeds of up to 12 m/s average with gusts up to 14 m/s (this being the safe operating wind speed limit for onshore wind turbine platforms and a practical limit for work on offshore platforms). In addition, then enclosure should survive without damage, or causing a safety hazard, wind speeds gusting up to 20 m/s. This is advantageously enabled by the small size of the enclosure, by comparison with prior art systems, minimising the enclosed volume required around a repair.

[0092] It is advantageously possible to set up the system ready for use within 10 minutes, and to recover the system and stow it within 5 minutes (for example, in the event of a change in weather).

[0093] The enclosure preferably provides a controlled internal working space at least 1000 mm wide, 1000 mm high and 500 mm from the surface of the blade. An operator can preferably insert both arms through sleeves into the internal working space, e.g. through elasticated or adjustable cuffs. This provides sufficient freedom of movement to carry out the repair procedures safely, comfortably and without difficulty. The operator is provided with a clear viewing panel that will allow the work to be carried safely, comfortably and without undue difficulty.

[0094] At least one resealable access port is provided so that tools and materials can be passed into the internal working space for use, and then sealed. The port should allow passing in and out of items with a maximum dimension of up to 300 mm. This is advantageously a linear opening, e.g. a zip, that is at least 500 mm long.

[0095] Power outlet sockets are provided within the working area, or a port is provided for passing power cables into the working area, large enough to pass an electrical plug, which can then seal around the cable(s). An access port resealable with hook-and-loop fastener would allow cables to pass then be resealed around the cables giving an adjustable snug fit. A linear opening at least 100 mm long is preferred. This feature could be combined with the access port if the positioning is practical.

[0096] There should be adequate light within the working space for the technician to illuminate and see the work easily. During daylight, diffuse light through the fabric may be sufficient.

[0097] For work at night, artificial lighting should be provided. LED lights may be preferred in order to avoid excessive heating in the enclosure. Suspension points above the working area should be provided to hang lights overhead.

[0098] The system should preferably operate from 115V to 240V, 50 or 60 Hz single phase AC supply from the platform or turbine auxiliary supply. The system may advantageously draw not more than 2000 W maximum. The system circuit should have an isolating switch and protective circuit breakers to prevent any operation or fault affecting the functioning of the platform.

[0099] The system should be light in weight (as it will be carried and deployed by hand, and it adds to the payload on the platform). The total weight of the system should not exceed 20 kg.

[0100] The system will be used in an industrial environment, sometimes offshore/marine. All parts (unless they are intentionally disposable/replaceable) should withstand normal use, handling, transport, deployment and recovery without damage or deterioration.

[0101] It should be possible to deploy, operate and recover the system correctly and without undue difficulty working from a suspended access platform, wearing the usual personnel protection equipment (gloves, helmet, eye protection, outdoor clothing, harness, fall arrest and work positioning lines, lifejacket, workboots, etc.). Ideally, no tools may be needed normally to deploy, operate and recover the enclosure. Where service access requires use of a tool (such as a screwdriver), this should be of a type readily available, and provided in the kit.

[0102] The enclosure system should be packable into ideally one (or as few as practicable) robust and waterproof cases or bags for storage, transport, deployment and use on site. The package should contain a complete kit of all items, including all tools and spares, needed for on-site use and support of one system. The weight of any item in its packing should be less than 25 kg maximum. Handles and attachment points should be provided for safe and easy lifting.

[0103] The system should be compatible with conventional access platforms, for accessing the blade or other structure for repair.

[0104] Advantageously, securing the enclosure to a blade or other structure does not damage the blade or structure, or require any modification to the blade or structure. The use of a vacuum seal may be particularly advantageous in this regards.