Patent Description:
Modern wind turbines are commonly used to supply electricity into the electrical grid. Wind turbines of this kind generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. Said rotation generates a torque that is normally transmitted through a rotor shaft to a generator, either directly or through the use of a gearbox. This way, the generator produces electricity which can be supplied to the electrical grid.

The wind turbine hub may be rotatably coupled to a front of the nacelle. The wind turbine hub may be connected to a rotor shaft, and the rotor shaft is then rotatably mounted in the nacelle using one or more rotor shaft bearings arranged in a frame inside the nacelle. The nacelle is a housing arranged on top of a wind turbine tower that contains and protects e.g. the gearbox (if present) and generator and, depending on the wind turbine, further components such as a power converter, and auxiliary systems.

Maintenance inside the wind turbine hub may be required periodically. pitch drives and pitch bearings, attachments of the blade root, lubrication systems, electrical systems and others may be inspected and repaired from the inside of the wind turbine hub, if needed.

Depending on the wind turbine configuration, operators can reach and access the hub through a variety of ways. In e.g. direct drive wind turbines, access may be available through the inside of the generator. In other configurations, and particularly configurations with a rotor shaft rotatably mounted in a frame in the nacelle, access may be provided through a hatch at the roof of the nacelle. An operator can exit the nacelle through the hatch in the roof and then enter into the hub through a hatch at the front side of the hub or a hatch at the rear side of the hub. When an operator exits the nacelle and makes his or her way to the hub, the operator is exposed to and unprotected from the exterior, e.g. rain, hail, wind gusts etc. Even though fall protection systems may be used, the procedure still supposes a health and safety issue and operators may experience anxiety during such procedures.

Document <CIT> discloses a wind turbine with access features for gaining access to the interior of a rotor hub. The access features comprise an access bridge extending between the nacelle and the rotor hub.

Document <CIT> discloses a wind turbine with a bridge to access the rotor hub from the nacelle.

Document <CIT> discloses a nacelle cover for wind turbines, wherein the nacelle cover comprises access hatches.

Document <CIT> discloses a wind turbine comprising a nacelle with a wall panel that can be opened for the personnel to enter the nacelle.

Another nacelle according to the prior art is described in document <CIT>.

Examples of the present disclosure provide methods and systems for accessing a wind turbine hub from a nacelle that at least partially resolve some of the aforementioned problems.

In a first aspect of the present disclosure, a nacelle configured to be mounted on top of a wind turbine tower is provided. The nacelle comprises a nacelle hatch for covering a nacelle opening at a side of the nacelle facing a wind turbine hub, wherein the nacelle hatch is completely supported by the nacelle when the hatch is closed. The nacelle hatch forms a passageway to an opening in the wind turbine hub at a side of the wind turbine hub facing the nacelle when the hatch is opened, the passageway comprising a first side structure at least partially obstructing a downwards view on a first side of the hub and a second side structure at least partially obstructing a downwards view on a second side of the hub, the second side being opposite to the first side.

In accordance with this aspect, a nacelle is provided which comprises a nacelle hatch which can reduce anxiety for operators when they need to access the hub from the nacelle. When opened, the hatch partially or completely obstructs a view downwards for an operator, which can reduce anxiety. Safety may be improved by having a protective structure reducing the chances of a fall. The hatch when closed is completely supported by the nacelle i.e. there is no connection to the hub. There are thus no components that are fixed or otherwise attached to the hub. Manufacture of the hub can be maintained as before i.e. without a passageway to the hub.

Obstructing a view may herein be understood as to block, hinder, alter or impede a view. A structure that obstructs a view at least partially may herein be understood as any structure that hinders a view, such that an operator notices a presence of the structure when looking and his/her view of objects or surroundings on another side of the structure is substantially different than in absence of the structure.

A passageway may be understood herein as any structure forming a way of passage for an operator between the nacelle and the hub. The passageway may be completely or only partially covered and may include complete or partial sidewalls. The structure of the passageway may be load bearing, partially load bearing or not load bearing.

In another aspect, a method for accessing a wind turbine hub from a nacelle, is provided. The method comprises opening a hatch at a front side of the nacelle, and deploying the hatch such that the hatch forms a passageway to an opening in the wind turbine hub at a rear side of the wind turbine hub. The passageway comprises a first side structure substantially blocking a downwards view on a first side of the hub and a second side structure substantially blocking a downwards view on a second side of the hub, the second side being opposite to the first side.

<FIG> illustrates a perspective view of one example of a wind turbine <NUM>. As shown, the wind turbine <NUM> includes a tower <NUM> extending from a support surface <NUM>, a nacelle <NUM> mounted on the tower <NUM>, and a rotor <NUM> coupled to the nacelle <NUM>. The rotor <NUM> includes a rotatable hub <NUM> and at least one rotor blade <NUM> coupled to and extending outwardly from the hub <NUM>. For example, in the illustrated embodiment, the rotor <NUM> includes three rotor blades <NUM>. However, in an alternative embodiment, the rotor <NUM> may include more or less than three rotor blades <NUM>. Each rotor blade <NUM> may be spaced about the hub <NUM> to facilitate rotating the rotor <NUM> to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub <NUM> may be rotatably coupled to an electric generator <NUM> (<FIG>) positioned within the nacelle <NUM> to permit electrical energy to be produced.

<FIG> illustrates a simplified, internal view of one example of the nacelle <NUM> of the wind turbine <NUM> of the <FIG>. As shown, the generator <NUM> may be disposed within the nacelle <NUM>. In general, the generator <NUM> may be coupled to the rotor <NUM> of the wind turbine <NUM> for generating electrical power from the rotational energy generated by the rotor <NUM>. For example, the rotor <NUM> may include a main rotor shaft <NUM> coupled to the hub <NUM> for rotation therewith. The generator <NUM> may then be coupled to the rotor shaft <NUM> such that rotation of the rotor shaft <NUM> drives the generator <NUM>. For instance, in the illustrated embodiment, the generator <NUM> includes a generator shaft <NUM> rotatably coupled to the rotor shaft <NUM> through a gearbox <NUM>.

It should be appreciated that the rotor shaft <NUM>, gearbox <NUM>, and generator <NUM> may generally be supported within the nacelle <NUM> by a support frame or bedplate <NUM> positioned atop the wind turbine tower <NUM>.

The nacelle <NUM> is rotatably coupled to the tower <NUM> through the yaw system <NUM> in such a way that the nacelle <NUM> is able to rotate about a yaw axis YA. The yaw system <NUM> comprises a yaw bearing having two bearing components configured to rotate with respect to the other. The tower <NUM> is coupled to one of the bearing components and the bedplate or support frame <NUM> of the nacelle <NUM> is coupled to the other bearing component. The yaw system <NUM> comprises an annular gear <NUM> and a plurality of yaw drives <NUM> with a motor <NUM>, a gearbox <NUM> and a pinion <NUM> for meshing with the annular gear <NUM> for rotating one of the bearing components with respect to the other.

Blades <NUM> are coupled to the hub <NUM> with a pitch bearing <NUM> in between the blade <NUM> and the hub <NUM>. The pitch bearing <NUM> comprises an inner ring and an outer ring. A wind turbine blade may be attached either at the inner bearing ring or at the outer bearing ring, whereas the hub is connected at the other. A blade <NUM> may perform a relative rotational movement with respect to the hub <NUM> when a pitch system <NUM> is actuated. The inner bearing ring may therefore perform a rotational movement with respect to the outer bearing ring. The pitch system <NUM> of <FIG> comprises a pinion <NUM> that meshes with an annular gear <NUM> provided on the inner bearing ring to set the wind turbine blade into rotation around a pitch axis PA.

<FIG> schematically illustrate an example of a nacelle hatch. <FIG> illustrates an isometric view of the wind turbine rotor and nacelle with a deployed hatch. <FIG> illustrates the same view, wherein the hatch has been made transparent to show component. <FIG> show a side view of the same nacelle and hatch. <FIG> schematically illustrates a method for deploying this same nacelle hatch.

<FIG> illustrates an isometric view of a nacelle <NUM> configured to be mounted on top of a wind turbine tower. The nacelle <NUM> comprises a nacelle hatch <NUM> for covering a nacelle opening at a side of the nacelle facing a wind turbine hub. The nacelle hatch is completely supported by the nacelle <NUM> when the hatch is closed. This may be seen in <FIG>.

The nacelle hatch <NUM> forms a passageway to an opening <NUM> in the wind turbine hub at a side of the wind turbine hub facing the nacelle when the hatch is opened. The passageway comprises a first side structure <NUM> at least partially obstructing a downwards view on a first side of the hub and a second side structure <NUM> at least partially obstructing a downwards view on a second side of the hub, the second side being opposite to the first side.

In the example of <FIG>, the wind turbine has the rotor upstream from the nacelle. The upstream or front surface of the nacelle <NUM> thus faces the hub, whereas the rear surface or downstream surface of the hub faces the nacelle. In other examples, the rotor may be arranged downstream from the nacelle.

The nacelle may further comprises side surfaces <NUM> and top surface or "roof" surface <NUM>. The nacelle may generally house the rotor shaft, gearbox (if present), and the generator. The rotor shaft may be rotatably mounted in the nacelle. Other components such as batteries, converters, power cables, A/C systems etc. may also be partially or completely contained within the nacelle <NUM>. The nacelle hatch may be arranged vertically above the rotor shaft, or above the bearing arrangement of the rotor shaft in the nacelle.

In some examples, the nacelle hatch <NUM> may comprise one or more panels hingedly mounted to the nacelle for forming the passageway. In the example of <FIG>, the nacelle hatch <NUM> comprises a first top panel <NUM> hingedly mounted to the nacelle <NUM>. Hinges <NUM> that allow rotation of the first top panel from covering an opening in the nacelle to an open position have been schematically illustrated.

A first side panel <NUM> hingedly mounted to the first top panel <NUM> to form at least part of the first side structure, and a second side panel <NUM> hingedly mounted to the first top panel <NUM> to form at least part of the second side structure. Hinges <NUM> have been schematically illustrated and may be seen e.g. in <FIG>.

In the example of <FIG>, the nacelle hatch <NUM> furthermore comprises a second top panel <NUM> hingedly mounted at a front edge of the first top panel <NUM>. Hinges <NUM> have been schematically illustrated in <FIG> at a front edge of the first top panel.

When an operator needs to access the hub, a path may be provided from the nacelle to the hub. The side panels <NUM> block the view of an operator downwards on either side of the hub, and may increase security by avoiding falls on either side of the hub when stepping from the nacelle to the hub.

<FIG> schematically illustrate side views of an example of a method for accessing the wind turbine hub <NUM> from the nacelle <NUM>. Before accessing the hub, the wind turbine rotor may have been rotated to one of a plurality of predetermined positions suitable for maintenance. In particular, three of such positions may be predefined, e.g. the three positions corresponding to a bunny ears configuration. In the bunny ears configuration, one of the blades is pointing straight down, whereas the other blades are pointing upwards.

Specifically, after rotating the hub to such a position or stopping the hub in such a position, the rotor may be locked in place. The rotor may be provided with a locking plate, and a bolt or pin may be inserted from the nacelle in a hole in the locking plate to secure the rotor in its position. However, one of the aspects of the nacelle hatches disclosed herein is that since the nacelle hatch can be completely supported by the hub, maintenance may potentially be carried out even when the rotor is not exactly in one of the predefined stopping or locking positions.

The method may then comprise opening a hatch <NUM> at a front side of the nacelle, as shown in <FIG>. The method then comprises deploying the hatch <NUM> such that the hatch <NUM> forms a passageway to an opening <NUM> in the wind turbine hub <NUM> at a rear side of the wind turbine hub <NUM>. The passageway comprises a first side structure <NUM> substantially blocking a downwards view on a first side of the hub and a second side structure <NUM> substantially blocking a downwards view on a second side of the hub, the second side being opposite to the first side.

The opening <NUM> in the wind turbine hub allowing access to the inside of the hub may be provided with a cover <NUM>. In some examples, cover <NUM> may be securely locked when in its opened position. Cover <NUM> in its opened position may be encompassed within the passageway formed by hatch <NUM>.

In the specific example of <FIG>, deploying the hatch <NUM> comprises pushing a first panel <NUM> hingedly mounted to the nacelle. The first panel <NUM> which is mounted to the nacelle may form a first top panel when deployed. The deploying of the hatch <NUM> may further comprise unfolding a plurality of panels <NUM>, <NUM> that are hingedly mounted to the first panel <NUM>.

In some examples, the hatch may be configured to selectively lock the panels in an opened position. This may apply to one or more or all of the panels. In <FIG>, the first top panel <NUM>, may be locked in place before unfolding the other panels. Locking of the panels may be done in a variety of ways, such as mechanically blocking with a latch or using a pneumatic or hydraulic system.

The other panels which are suspended from the first top panel may also be locked in an open position by suitable mechanical, electrical, pneumatic or hydraulic systems.

In the example illustrated in <FIG>, and particularly in <FIG>, the hatch when opened may be supported by the hub. In other examples, the hatch, when opened, may still be fully supported by the nacelle.

In some examples, the hatch <NUM> may be configured to be manually opened and closed. An operator may in the example of <FIG> grab the first top panel and push it open. After securing the first top panel in the open position, the operator may then unfold the side panels <NUM> and unfold the second top panel <NUM>. To retract the hatch, e.g. after maintenance inside the hub has been completed, the procedure may be followed in opposite order. In alternative examples, a system involving motors and/or pistons may be used to automatically or semi-automatically deploy the hatch when needed and also to retract the hatch.

<FIG> schematically illustrates a further example of a nacelle hatch <NUM>. In this example, the nacelle hatch comprises a first side panel <NUM> hingedly mounted to the nacelle <NUM> for forming the first side structure, and a second side panel <NUM> hingedly mounted to the nacelle <NUM> for forming the second side structure. As in the example of <FIG>, the side panels block or at least partially obstruct a downwards view of an operator wanting the access an opening <NUM> in the hub.

In the example of <FIG>, the hatch when deployed to an open position, the operator is protected from the exterior e.g. hail, rain, wind gusts etc. In the example of <FIG>, the hatch only protects the operator on the sides, but this can be sufficient for reducing anxiety of operators.

In some examples, when the hatch is opened, the first and second side panels <NUM> extend substantially to a top surface of the hub. the side panels <NUM> may be partially supported by the hub. The side panels are herein shown to be substantially rectangular. In other examples, the shape of the side panels may be irregular, e.g. the corners may be adapted to mate with a shape of the surface of the hub.

<FIG> schematically illustrates yet a further an example of a nacelle hatch. In the example of <FIG>, the nacelle hatch <NUM> comprises an expandable structure, which when expanded extends between an opening in the nacelle and the opening in the hub.

The passageway formed between the nacelle and the hub may be closed on the top and on either side such that operators are generally well protected from the exterior.

In the examples of <FIG>, the expandable structure may comprise a bellows. The bellows may include a plurality of pleats <NUM>, <NUM>, <NUM>, <NUM> which be collapsed on top of each other in the closed position of the hatch. In the open position or open configuration of the hatch <NUM>, the pleats <NUM>, <NUM>, <NUM>, <NUM> are separated from each other.

The hatch <NUM> may include a handle which an operator may grasp to push the hatch <NUM> towards the hub, and/or to pull the hatch back towards the nacelle. In other examples, opening and closing the hatch may be automatic, using e.g. an electric motor, pneumatic or hydraulic system.

In accordance with examples disclosed herein, a wind turbine may comprise a tower, a nacelle arranged on top of the tower, and a rotor including a rotor hub and a plurality of wind turbine blades. The rotor (e.g. rotor shaft) may be rotatably mounted with respect to the nacelle, and the nacelle may comprises a nacelle opening at an upstream side of the nacelle, and the hub comprises a hub opening at a downstream side of the hub. The nacelle comprises a nacelle hatch, the nacelle hatch covering the nacelle opening in a first configuration, and the nacelle hatch forming a passage to the hub opening in a second configuration. The nacelle hatch in the second configuration includes at least a protective structure on both sides of the passage.

A protective structure may herein be understood as any structure that increases security or protection for an operator to some extent when passing from the nacelle to the hub or vice versa. The protective structure may be completely secure in that an operator does not need to latch him/herself on to a safety line. In some examples, the protective structure may be sufficiently strong and stiff for operators to use it as a support and to be able to lean against it. In other examples, the protective structure may not be able to carry such loads but may still increase security for operators by blocking or reducing weather influences or by reducing anxiety for operators as hereinbefore explained.

In some examples, the nacelle hatch in the second configuration may include a protective structure at a top of the passage, such as shown in e.g. <FIG> and <FIG>.

In some examples, the nacelle hatch may comprise a plurality of unfoldable panels, such as shown in e.g. <FIG> and <FIG>. At least one of the plurality panels may be hingedly mounted to the nacelle.

In some examples, the nacelle hatch may comprise an expandable structure, such as shown in <FIG>. In the example of <FIG>, the expandable structure comprises a bellows, which may be a slidable bellows or corrugated bellows. In other examples, the expandable structure may include a telescopic structure, or telescopic elements.

Claim 1:
A nacelle (<NUM>) configured to be mounted on top of a wind turbine tower (<NUM>) and comprising a nacelle hatch (<NUM>, <NUM>) for covering a nacelle opening at a side of the nacelle (<NUM>) facing a wind turbine hub (<NUM>), wherein
the nacelle hatch (<NUM>, <NUM>) is completely supported by the nacelle (<NUM>) when the hatch (<NUM>, <NUM>) is closed, and
the nacelle hatch (<NUM>, <NUM>) is configured to be deployed from a closed position in which it covers the nacelle opening to an open position in which it forms a passageway to an opening (<NUM>) in the wind turbine hub (<NUM>) at a side of the wind turbine hub (<NUM>) facing the nacelle (<NUM>),
the passageway comprising a first side structure (<NUM>) at least partially obstructing a downwards view on a first side of the hub (<NUM>) and a second side structure (<NUM>) at least partially obstructing a downwards view on a second side of the hub (<NUM>), the second side being opposite to the first side.