Procedures for the maintenance and / or repair of a wind turbine

Abstract

A method for the maintenance and / or repair of a wind turbine, wherein a rotor of the wind turbine with a rotor hub having a rotor blade bearing (10) is arranged on a tower of the wind turbine, wherein a ring element (11) of the rotor blade bearing is rotatable with respect to a further ring element (13) of the rotor blade bearing which is fixed with respect to the rotor hub, wherein a rotor blade of the rotor is attached to the ring element, wherein an angle of attack of the rotor blade with respect to the rotor hub is adjustable by a rotation of the ring element, characterized in that at least one worn tooth (14) of a toothing (12) of the ring element is machined by welding until the tooth is brought into a predetermined, preferably at least approximately original, state of the tooth, wherein the rotor blade bearing is at least partially, in particular the ring element in a region surrounding the tooth,During welding, cooling is carried out using a cooling device, with maintenance and / or repair being performed in situ.

Description

[0001] The invention relates to a method for the maintenance and / or repair of a wind turbine, wherein a rotor of the wind turbine is arranged on a tower of the wind turbine with a rotor hub having a rotor blade bearing, wherein a ring element of the rotor blade bearing is rotatable with respect to a further ring element of the rotor blade bearing that is fixed with respect to the rotor hub, wherein a rotor blade of the rotor is fastened to the ring element, wherein an angle of attack of the rotor blade with respect to the rotor hub is adjustable by rotating the ring element.

[0002] Wind turbines are well known in the art. They typically comprise a tower and a rotor mounted on the tower, which in turn comprises a rotor hub and typically two or three rotor blades attached to the rotor hub. In order to adjust the angle of attack of a rotor blade relative to the rotor hub in order to regulate the power of a wind turbine, the rotor hub typically comprises a rotor blade bearing designed as a rolling bearing for each rotor blade, which comprises a ring element, a further ring element, and rolling elements arranged between the ring element and the further ring element. The ring element is rotatable relative to the further ring element, which is fixed relative to the rotor hub, so that the angle of attack of the rotor blade can be adjusted by rotating the ring element when the rotor blade or rotor blade flange of the rotor blade is attached to the ring element.To carry out the rotation, the ring element usually has a toothing which engages with a counter toothing of a gear of a transmission device of a rotor blade adjustment device of the rotor hub, so that by means of a drive device of the rotor blade adjustment device, such as an electric motor, a torque can be applied to the ring element via the toothed wheel, as a result of which the rotation of the ring element with respect to the further ring element or the rotor hub can take place.

[0003] The usable range of the gearing in a wind turbine with this type of rotor blade adjustment is typically 90°, with the rotor blades each moving within a range of 0° to 90°. A range of 0° to 5° is considered the working range. In this working range, particularly at 0° within the working range, the gearing is subject to increased wear, which is attributable to increased abrasion of the gear teeth located within the working range due to insufficient lubrication. This insufficient lubrication results in particular from the fact that a lubricant applied to the teeth is increasingly displaced due to the constant movement of the rotor blades.Alternating loads occurring with each rotation of the rotor, whereby the teeth of the gearing continuously interact with the meshing teeth of the gear of the rotor blade pitch device, contribute to increased wear of the gearing or teeth of the gearing. Ultimately, a worn tooth can even break out. Gearing that has become worn or worn due to wear leads to massive impacts in the rotor with each rotation of the rotor, which can damage the rotor blade bearing or the interior of the rotor blade bearing and other components of the wind turbine or the rotor, which must be prevented.

[0004] Therefore, DE 10 2010 062 418 A1 discloses a method for maintaining a wind turbine. When a wear limit of the teeth is reached and the rotor blade flange is detached from the ring element, the ring element is rotated relative to the rotor blade flange so that teeth of the gearing that are not yet worn engage with the teeth of the counter-gearing, and the working area after rotation of the ring element is thus formed by teeth of the gearing that are not yet worn. This requires complex disassembly of the rotor blades. The occurrence of further impacts in the rotor can thus initially be prevented, so that the wind turbine can continue normal operation after the method has been carried out until such time as another such repair is necessary.Due to the mandatory dismantling of the rotor blades as part of the aforementioned procedure, carrying out this procedure involves considerable effort and is costly.

[0005] The present invention is therefore based on the object of specifying a method which enables simplified and cost-effective maintenance and / or repair of a wind turbine.

[0006] This object is achieved by a method having the features of claim 1.

[0007] In the method according to the invention for the maintenance and / or repair of a wind turbine, a rotor of the wind turbine with a rotor hub having a rotor blade bearing is arranged on a tower of the wind turbine, wherein a ring element of the rotor blade bearing is rotatable relative to a further ring element of the rotor blade bearing that is stationary relative to the rotor hub, wherein a rotor blade of the rotor is fastened to the ring element, wherein an angle of attack of the rotor blade relative to the rotor hub is adjustable by rotating the ring element, wherein at least one worn tooth of a toothing of the ring element is machined by welding until the tooth is brought into a predetermined, preferably at least approximately original, state of the tooth, wherein the rotor blade bearing is cooled at least in part, in particular the ring element in a region surrounding the tooth, during welding using a cooling device,where maintenance and / or repair is carried out in situ.,

[0008] The term “maintenance” refers in particular to measures that are carried out on a tooth before it reaches its wear limit.

[0009] The term “repair” refers in particular to measures that are carried out on a tooth after it has reached its wear limit.

[0010] The term “condition of the tooth” refers in particular to a geometric shape of the tooth, a micrograph of the tooth and mechanical properties of the tooth, in particular a hardness of the tooth and a tensile strength of the tooth.

[0011] The term "worn tooth" refers to a tooth that is showing signs of wear, although the tooth may not yet have reached its wear limit or may already have reached it. This term can also extend to a tooth that is essentially avulsed.

[0012] According to the invention, at least one worn tooth of the gearing, preferably all worn teeth of the gearing, is machined by welding for the maintenance or repair of the tooth or the wind turbine until the tooth is restored to a predetermined, preferably approximately original, condition. In other words, the tooth can be welded on.

[0013] According to the invention, the rotor blade bearing is cooled at least in part, in particular the ring element in a region surrounding the tooth, during welding using a cooling device. This makes it possible to avoid heat build-up. In particular, it is possible to prevent components of the wind turbine adjacent to the rotor blade bearing or the rotor blade bearing itself, in particular hardened regions of the rotor blade bearing, from becoming excessively hot. In particular, this makes it possible to prevent the temperature of the ring element in a region of the raceway or in a fastening region of the rotor blade from exceeding a critical temperature, so that damage to the raceway or the rotor blade can be prevented. The cooling device can comprise at least one cooling unit, which can be arranged on the ring element, for example in a bore or through-opening of the ring element.Advantageously, the cooling device can operate on a water-cooled basis. For example, a copper coil through which water can flow can be provided as the cooling device.

[0014] According to the invention, maintenance and / or repair is carried out in situ. In other words, the maintenance and / or repair is carried out while the rotor blade bearing is installed in the wind turbine. Removal of the rotor blade bearing is therefore not necessary. Instead, maintenance or repair can be carried out from within the rotor hub, with a service technician installed in the rotor hub performing the process steps.

[0015] After maintenance or repair of the tooth, the tooth lies within a working area of ​​the gearing. The ring element is therefore not rotated in such a way that the maintained or repaired tooth lies outside the working area. Since the maintained or repaired teeth are robust enough to continue to form the working area for rotor blade adjustment, a complex and cost-intensive rotation of the ring element with the rotor blade detached from the ring element is not necessary. As a result, the method according to the invention enables comparatively simple and cost-effective maintenance or repair of a wind turbine.

[0016] Rolling elements of the rotor blade bearing can be arranged between the ring element and the further ring element. The rotor blade bearing can therefore be a rolling bearing. Furthermore, the ring element can form an inner ring of the rotor blade bearing, and a further ring element of the rotor blade bearing can form an outer ring of the rotor blade bearing, wherein the toothing of the ring element can form an internal toothing of the inner ring. Alternatively, the ring element can form an outer ring of the rotor blade bearing, and the further ring element can form an inner ring of the rotor blade bearing, wherein the toothing of the ring element can form an external toothing of the outer ring. The rolling elements of the rotor blade bearing can then be arranged between the inner ring and the outer ring.

[0017] Advantageously, the tooth can be brought into an at least approximately original geometric shape by deposition welding, which involves applying a filler metal to a base material of the tooth or a base material of the tooth. Tungsten inert gas welding (TIG welding) can advantageously be used for this purpose. UTP A 651, for example, can be used as the filler metal or deposition material.

[0018] Advantageously, the tooth can be preheated before welding, and the tooth can be cooled after welding, wherein the preheating and cooling can be carried out in such a way that martensite formation in a material of the tooth can be substantially prevented. The term "tooth material" refers to both a base material of the tooth, in particular the original one, and a welding filler material that forms or co-forms the tooth after welding. In order to substantially prevent martensite formation in a material or microstructure of the tooth, the tooth or the material of the tooth can be preheated before welding and cooled after welding, wherein a preheating rate and a cooling rate can be selected such that the microstructure of the tooth cannot transform into a martensitic microstructure.The presence of martensite in the tooth structure significantly increases the risk of crack formation in the tooth, so its formation must be avoided. Advantageously, preheating can be comparatively fast and cooling comparatively slow. It can also be provided to cool the rotor blade bearing or the ring element during preheating and / or cooling, at least in part or in the area surrounding the tooth, using the cooling device. The method can also be used, in particular, for a ring element or rotor blade bearing made of 42CrMo4. This material does not inherently have good welding properties, but the combination of preheating and cooling enables this material to be processed by welding.

[0019] Advantageously, preheating and cooling can be carried out in such a way that defects in the weld, in particular cracks, lack of fusion, or the like, are substantially avoided. In particular, lack of fusion in a transition zone, where the base material adjoins the filler metal, can be avoided by a suitable choice of preheating and cooling rates.

[0020] Advantageously, the preheating and / or cooling can be carried out using a heating device, preferably an inductive one. For controlled cooling of the tooth, the tooth can be heated after welding using the heating device, whereby the heating power of the heating device can be successively reduced to control the temperature of the tooth. During preheating, the heating device can be operated at maximum heating power. Advantageously, the heating device can be a mobile induction device.

[0021] In an advantageous embodiment of the method, the preheating can be controlled based on a heating curve stored in the heating device and / or the cooling can be controlled based on a cooling curve stored in the heating device. For this purpose, a preheating rate or cooling rate, or parameters describing the heating and cooling curves, can be input into the heating device by an operator.

[0022] Advantageously, the tooth or a base material of the tooth can be preheated to a temperature of 180°C to 220°C. However, lower or higher temperatures are also conceivable.

[0023] Advantageously, the temperature of the rotor blade bearing, in particular of the ring element, can be monitored at least in certain areas during preheating and / or welding and / or cooling. This can be accomplished, for example, using a temperature sensor, a thermometer, or a thermal imaging camera. It is possible to monitor the temperature in a region of the tooth and / or in a region surrounding the tooth. It is also possible to monitor the temperature of the ring element in a region intended for fastening a rotor blade or rotor blade flange. In particular, the temperature can be monitored during welding in order to initiate appropriate measures when a critical temperature is reached to prevent damage to the ring element or rotor blade bearing or rotor blade caused by heat.

[0024] The rotor blade can be fastened to the ring element by means of a rotor blade flange of the rotor blade using a plurality of fastening means of the rotor. The fastening means can comprise fastening bolts and fastening nuts. The fastening bolts can each engage in or pass through through-openings of the ring element. Furthermore, the fastening bolts can have a thread that can be brought into engagement with a thread of the through-openings. The through-openings can be formed in the form of a bolt circle in the ring element or in a ring body of the ring element.

[0025] Advantageously, a cooling device of the cooling apparatus can be arranged in a bore of the rotor blade bearing, in particular of the ring element. The bore can, in particular, be a through-opening of the ring element provided for inserting a fastening means.

[0026] Furthermore, the rotor blade can be fastened to the ring element by means of a rotor blade flange of the rotor blade by means of a plurality of fastening means of the rotor. The fastening means can each be inserted into a through-opening of the ring element. At least one fastening element inserted into a through-opening adjacent to the tooth can be removed from the through-opening. A cooling device can be arranged in the through-opening. The ring element can be cooled in a region surrounding the tooth during welding using the cooling device. For example, the toothing can have four worn teeth forming a working area, which are to be repaired.In order to ensure that the temperature of the ring element in the area of ​​the raceway and in the area where the rotor blade is fastened does not exceed a critical temperature, a fastening means substantially opposite the tooth can be removed from a through-hole into which the fastening means is inserted for each of the four teeth, so that a cooling device, for example in the form of a copper coil, can then be arranged in each of the four exposed through-holes in order to cool an area surrounding the teeth to be welded. Heat introduced into a tooth by welding can thus be directly removed again in an area opposite the tooth or the weld point, thus preventing heat build-up. Cooling can also take place during preheating. After welding orOnce cooled, the fastener can be reinserted into the through hole.

[0027] Advantageously, the tooth can be machined after welding or cooling by machining, in particular grinding and / or milling. This allows the tooth to be brought from its approximately original state to a substantially original state. The welded tooth can be ground or milled by hand. However, a mobile grinding or milling machine can also be provided, by means of which the machining can be carried out automatically. After machining, a template can be used to check whether the maintained or repaired tooth has reached the desired, predetermined condition. Hardness measurements can also be performed to check the condition of the tooth.

[0028] Furthermore, a mating toothing of a gearwheel of a transmission device of a rotor blade adjustment device of the rotor hub can engage with the toothing in a working range, wherein at least one tooth of the mating toothing that has become worn as a result of an interaction between the mating toothing and the toothing can lie within the working range before maintenance and / or repair of the tooth, wherein the gearwheel can be rotated by actuating the rotor blade adjustment device at the latest after maintenance and / or repair of the tooth in such a way that the tooth of the mating toothing lies outside the working range. The teeth of the mating toothing of the gearwheel are also subject to continuous wear as a result of interaction with the teeth of the toothing, although this wear is generally less than that of the teeth of the toothing. By rotating the gearwheel in such a way that in the working range of the mating toothing orIf, in a 0° position of the working range, essentially still unworn or unstressed teeth of the mating toothing engage with the maintained or repaired tooth of the toothing, renewed wear of the tooth of the toothing can be slowed. Damage to the gear can also be prevented by the rotation. The rotation can be carried out by actuating the rotor blade pitching device or a drive device of the rotor blade pitching device, in which the ring element or the rotor blade can be rotated by an integer multiple of 360°, for example three or four times by 360°. After the rotation, the rotor blade can then be back in a 0° position, in which the still unworn teeth of the mating toothing can engage with the maintained or repaired teeth of the toothing.

[0029] Alternatively, the gear can also be replaced, especially if the teeth of the counter gear have reached a wear limit.

[0030] Furthermore, a lubricant can be applied to the gear teeth and / or the counter-gear teeth. In particular, the lubricant can be applied to the maintained or repaired teeth.

[0031] A preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawings.

[0032] They show: Fig. 1 a schematic representation of a rotor blade bearing known from the prior art; Fig. 2 a graphical representation of a temperature curve during the implementation of the procedure.

[0033] The Fig. 1 shows a schematic representation of a rotor blade bearing 10 known from the prior art and designed as a rolling bearing, which comprises a ring element 11 with a toothing 12 and a further ring element 13. Rolling elements of the rotor blade bearing 10 (not shown here) are arranged between the ring element 11 and the further ring element 13. The ring element 11 forms an inner ring of the rotor blade bearing 10, and the further ring element 13 forms an outer ring of the rotor blade bearing 10, with the toothing 12 of the ring element 11 forming an internal toothing of the inner ring. The toothing 12 has a plurality of teeth 14. Furthermore, the ring element 11 has a plurality of through-openings 15 forming a hole circle, and the further ring element 13 has a plurality of through-openings 16 forming a further hole circle.By means of fastening means (not shown here) which can pass through the through-openings 16, the rotor blade bearing 10 can be arranged on a rotor hub (not shown here) such that the further ring element 13 is fixed with respect to the rotor hub, wherein the ring element 11 is rotatable with respect to the further ring element 13. The through-openings 15 serve to fasten a rotor blade (not shown here), which can be fastened to the ring element 11 by means of further fastening means (not shown here) which can pass through the through-openings 15. An adjustment of an angle of attack of the rotor blade with respect to the rotor hub can then be achieved by rotating the ring element 11 with respect to the further ring element 13 or the rotor hub.

[0034] The Fig.2 shows a temperature-time diagram 17, wherein a time 31 in the form of a time is plotted on a time axis 18 of the temperature-time diagram 17 and a temperature 20 in °C is plotted on a temperature axis 19 of the temperature-time diagram 17. The temperature-time diagram 17 shows a temperature profile 21 during the implementation of an advantageous embodiment of the method according to the invention, wherein four adjacent, worn teeth of a toothing of a ring element of a rotor blade bearing are repaired. The temperature profile 21 has four sections 22, 23, 24 and 25, wherein each section 22, 23, 24 and 25 reflects a repair of one of the four teeth. It can also be seen that an upper curve 26 and a lower curve 27 are shown in the temperature-time diagram 17.The upper curve 26 shows the temperature profile 21 at a tooth opposite a weld point, while the lower curve 27 shows the temperature profile 21 at an upper side of the rotor blade bearing adjacent to a tooth. As an example, the temperature profile 21 will now be explained in more detail using section 23, which shows the repair of the second tooth. It can be seen that section 23 comprises three regions 28, 29, and 30. In region 28, the temperature 20 rises steeply as a result of preheating of the tooth at maximum power of an induction device used for this purpose. In region 29, the tooth is machined by welding, with a filler material being applied to a base material of the tooth until the tooth is brought into at least approximately its original geometric shape.Finally, the temperature 20 in the region 30 drops comparatively slowly due to controlled cooling of the tooth. The preheating and cooling of the tooth are carried out in such a way that martensite formation in a microstructure of the tooth as well as defects in the weld are substantially avoided. In particular, during welding, the ring element is cooled in a region surrounding the teeth using a cooling device, thereby preventing possible damage to the rotor blade bearing, in particular to hardened running surfaces of the rotor blade bearing, and to a rotor blade attached to the ring element.For this purpose, for each of the four teeth, a fastening means substantially opposite the tooth and intended for fastening the rotor blade to the ring element is removed from a through-hole in the ring element into which the fastening means is inserted. This means that a cooling device of the cooling apparatus, for example in the form of a copper coil, can subsequently be arranged in each of the four exposed through-holes to cool an area surrounding the teeth to be welded. Maintenance or repair is carried out in situ from a rotor hub containing the rotor blade bearing. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102010062418 A1

[0004]

Claims

[1] Method for the maintenance and / or repair of a wind turbine, wherein a rotor of the wind turbine is arranged on a tower of the wind turbine with a rotor hub having a rotor blade bearing (10), wherein a ring element (11) of the rotor blade bearing is rotatable with respect to a further ring element (13) of the rotor blade bearing that is fixed with respect to the rotor hub, wherein a rotor blade of the rotor is fastened to the ring element, wherein an angle of attack of the rotor blade with respect to the rotor hub is adjustable by a rotation of the ring element, characterized bythat at least one worn tooth (14) of a toothing (12) of the ring element is machined by welding until the tooth is brought into a predetermined, preferably at least approximately original, state of the tooth, wherein the rotor blade bearing is cooled at least in some regions, in particular the ring element in a region surrounding the tooth, during welding using a cooling device, wherein the maintenance and / or repair is carried out in situ. [2] Method according to claim 1, characterized by that the tooth (14) is brought into an at least approximately original geometric shape by build-up welding by applying a welding filler material to a base material of the tooth. [3] Method according to claim 1 or 2, characterized bythat the tooth is preheated before welding, wherein the tooth is cooled after welding, wherein the preheating and cooling are carried out in such a way that martensite formation in a material of the tooth is substantially avoided. [4] Method according to claim 3, characterized by that preheating and cooling are carried out in such a way that defects in the weld, in particular cracks, lack of fusion or the like, are essentially avoided. [5] Method according to claim 3 or 4, characterized by that the preheating and / or cooling is carried out using a, preferably inductive, heating device. [6] Method according to claim 5, characterized by that the preheating is controlled by means of a heating curve stored in the heating device and / or the cooling is controlled by means of a cooling curve stored in the heating device. [7] Method according to one of claims 3 to 6, characterized bythat the tooth (14) is preheated to a temperature (20) of 180 °C to 220 °C. [8] Method according to one of claims 3 to 7, characterized by that a temperature (20) of the rotor blade bearing (10), in particular of the ring element (11), is monitored at least in some areas during preheating and / or cooling. [9] Method according to one of the preceding claims, characterized by that a temperature (20) of the rotor blade bearing (10), in particular of the ring element (11), is monitored at least in some areas during welding. [10] Method according to one of the preceding claims, characterized byin that the rotor blade is fastened to the ring element by means of a rotor blade flange of the rotor blade by means of a plurality of fastening means of the rotor, wherein the fastening means are each inserted into a through-opening (15) of the ring element (11), wherein at least one fastening means inserted into a through-opening adjacent to the tooth (14) is removed from the through-opening, wherein a cooling device of the cooling device is arranged in the through-opening, wherein the ring element is cooled in a region surrounding the tooth during welding using the cooling device. [11] Method according to one of the preceding claims, characterized by that the tooth (14) is machined after welding by machining, in particular grinding and / or milling. [12] Method according to one of the preceding claims, characterized byin that a counter-toothing of a gearwheel of a transmission device of a rotor blade adjustment device of the rotor hub is in engagement with the toothing (12) in a working range, wherein at least one tooth of the counter-toothing that is worn as a result of an interaction between the counter-toothing and the toothing lies within the working range before maintenance and / or repair of the tooth, wherein the gearwheel is rotated by actuation of the rotor blade adjustment device at the latest after maintenance and / or repair of the tooth in such a way that the tooth of the counter-toothing lies outside the working range.

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