Patent Description:
The generator in a wind turbine, such as a direct drive wind turbine, is usually equipped with some kind of cooling system, e.g., in the form of a ventilation system that blows a cooling fluid through the stator cavity before it is exhausted to the surroundings. In so-called direct drive wind turbines where the generator is coupled directly to the rotor and hence arranged between the rotor and the nacelle, space limitations and other constraints present a challenge in the design of such cooling systems, in particular with regard to exhausting the used (hot) cooling fluid. Some known solutions involve an extensive amount of ducts and piping that is guided from the generator and through the nacelle in complicated ways such that it does not interfere with other parts and/or prevents access thereto. Relevant background-art examples of such solutions are disclosed in for instance <CIT> and <CIT>.

Hence, there may be a need for simple and efficient cooling solutions that are easy to implement without interfering with room or accessibility constraints.

According to a first aspect of the invention, a canopy for a direct drive wind turbine is provided. The canopy comprises an interface section configured for mechanically coupling the canopy to a generator, wherein the interface section comprises at least one outlet configured to receive cooling fluid exhausted by the generator and eject the received cooling fluid.

This aspect of the invention is based on the idea that at least one outlet is formed in the interface section such that the cooling fluid exhausted by the generator can be ejected directly to the outside surroundings of the wind turbine without the need for long and complex arrangements of ducts. In particular, the exhausted cooling fluid is not guided into the nacelle.

According to an embodiment of the invention, the interface section forms a circumferential shape about an axial direction of the wind turbine.

In other words, the interface section surrounds the axial direction and may in particular be formed as a round or circular section capable of being mechanically coupled to the generator of the direct drive wind turbine.

According to the first aspect of the invention, the interface section comprises a tubular member extending in the axial direction of the wind turbine.

The tubular member may extend from the main part of the canopy towards the generator. The length (in the axial direction) of the tubular member is generally kept as short as possible in order to not extend the axial dimensions of the canopy more than necessary.

According to a further embodiment of the invention, the at least one outlet is formed in the tubular member and configured to eject the received cooling fluid in a radial direction.

In other words, the short tubular member provides a surface in which the at least one outlet is formed, such that the cooling fluid is ejected radially outwards.

The outlet may have a circular, elliptic, rectangular or any other shape that provides a sufficient cross-sectional area for ejecting the used cooling fluid.

This embodiment is particularly advantageous as it does not require any modification of the cross-sectional shape of the interface section of the canopy.

According to a second aspect of the invention, the interface section comprises at least one radial protrusion in which the at least one outlet is formed.

In other words, the interface section is extended (in comparison to known interface sections) with at least one protrusion in the radial direction. The at least one protrusion allows forming of the at least one outlet.

This embodiment is particularly advantageous as it does not require any substantive extension of the interface section of the canopy in the axial direction.

According to a further embodiment of the invention, the at least one outlet is configured to eject the received cooling fluid in the axial direction.

In other words, the at least one outlet takes up a minimum of space in the axial direction.

According to the second aspect of the invention, a cavity is formed between the canopy and the at least one radial protrusion, and the at least one outlet is configured to eject the received cooling fluid into the cavity.

The cavity assures that the used cooling fluid is ejected to the surroundings of the wind turbine generator.

According to a further embodiment of the invention, the at least one outlet comprises a plurality of outlets.

The plurality of outlets may in particular be arranged along the perimeter of the interface section with equal spacing between each outlet.

The plurality of outlets may comprise any number of outlets, such as in particular two, three, four, five, six, eight, <NUM> or <NUM> outlets.

According to a third aspect of the invention there is provided a direct drive wind turbine comprising a rotor, a generator, and a nacelle arranged at an upper end of a tower. The nacelle comprises a canopy according to the first aspect or any of the above embodiments thereof.

This aspect of the invention is generally based on the same idea as the first and second aspect and provides a wind turbine which benefits from the advantageous canopy of the first aspect as discussed above.

According to a further embodiment of the invention, the generator comprises at least one ventilation unit adapted to exhaust the cooling fluid towards the at least one outlet of the canopy.

The at least one ventilation unit, such as a fan or blower, is preferably arranged close to the periphery of the generator and close to the corresponding at least one outlet of the canopy.

According to a further embodiment of the invention, the wind turbine further comprises at least one duct arranged to guide the exhausted cooling fluid to the at least one outlet.

The duct may in particular be arranged between the at least one ventilation unit and the at least one outlet. Alternatively, the duct may comprise the at least one ventilation unit.

According to a further embodiment of the invention, the cooling fluid is air.

The cooling air is sucked in from the surroundings of the wind turbine generator and blown and/or sucked through the stator cavity before it is exhausted from the generator and ejected through the at least one outlet in the canopy.

The aspects defined above and further aspects of the present invention are apparent from the examples of embodiments to be described hereinafter and are explained with reference to the examples of embodiments. The invention will be described in more detail hereinafter with reference to examples of embodiments. However, it is explicitly noted that the invention is not limited to the described exemplary embodiments.

The illustration in the drawing is schematic. It is noted that in different figures, similar or identical elements are provided with the same reference numerals or with reference numerals which differ only within the first digit.

<FIG> shows a direct drive wind turbine <NUM> according to an exemplary embodiment of the present invention. The wind turbine <NUM> comprises a nacelle enclosed in a canopy <NUM> and arranged at the upper end of tower <NUM>. The canopy <NUM> comprises an interface section <NUM> which is mechanically coupled to generator <NUM> which is arranged between the canopy <NUM> and the rotor <NUM> of the wind turbine <NUM>. The interface section <NUM> of the canopy <NUM> comprises several outlets <NUM> for ejecting cooling fluid exhausted by the generator <NUM>.

<FIG> shows a partial view of a canopy <NUM> according to an exemplary embodiment of the present invention. The canopy <NUM> comprises an interface section formed as a relatively short tubular member <NUM> with outlets <NUM> in the tubular surface of the interface section <NUM>. A short duct <NUM> is inserted in each outlet opening <NUM>. The ducts <NUM> are formed to receive used cooling fluid, e.g. hot air, exhausted by the generator (not shown) in the axial direction eject the fluid through the corresponding outlet opening <NUM> in the radial direction. The interface section <NUM> also comprises a flange or lip <NUM> configured to engage with a corresponding structure in the generator. In the present exemplary embodiment, eight outlets <NUM> and corresponding ducts <NUM> are arranged around the circumference of the tubular member <NUM>. However, any number of outlets <NUM>, such as one, two, three, four, six, <NUM> or <NUM> outlets <NUM>, may be feasible and used in other embodiments of the present invention.

<FIG> shows the set of ducts <NUM> used in the exemplary embodiment shown in <FIG>. As shown, each duct <NUM> comprises an inlet opening <NUM> pointing in the axial direction of the wind turbine and thereby configured to receive cooling fluid from the generator (not shown). Furthermore, each duct <NUM> comprises a bent duct portion <NUM> shaped to change the flow direction of the exhaust cooling fluid from the axial to a radial direction corresponding to the orientation of the duct outlet <NUM> which fits into the outlet opening <NUM> shown in <FIG>.

<FIG> shows a partial view of the canopy <NUM> and a generator <NUM> according to the exemplary embodiment shown in <FIG>. The generator <NUM> comprises a ventilation unit (fan or blower) <NUM> arranged to convey exhausted cooling fluid from inside the generator <NUM> to the duct <NUM> such that it can be ejected in the radial direction through the duct outlet <NUM>.

<FIG> shows a first partial view of a canopy <NUM> according to a further exemplary embodiment of the present invention. This embodiment differs from the one discussed above in conjunction with <FIG> in the shape of the interface structure <NUM> which comprises radial protrusions <NUM> extending inwards towards the axis of the wind turbine in order to accommodate axial fluid outlets (not shown in <FIG> but discussed further below in conjunction with <FIG>) that are in communication with ducts <NUM> providing the exhaust cooling fluid from the generator (not shown).

<FIG> shows a second partial view of the canopy <NUM> according to the further exemplary embodiment shown in <FIG>. In this second partial view, one of the outlets <NUM> can be seen. Furthermore, it can be seen that the outlet <NUM> ends in a small pocket formed in the protrusion <NUM> (see <FIG>) and thus ejects the received cooling fluid in the axial direction.

<FIG> shows a partial view of canopy <NUM> and generator <NUM> according to the further exemplary embodiment shown in <FIG>. Like in the embodiment discussed in conjunction with <FIG>, the generator <NUM> comprises a ventilation unit (fan or blower) <NUM> arranged to convey exhausted cooling fluid from inside the generator <NUM> to the duct <NUM> such that it can be ejected in the axial direction through the duct outlet <NUM> and into the pocket formed in the protrusion <NUM> before escaping to the surroundings of the wind turbine.

<FIG> shows a cross-sectional view of the generator <NUM> shown in <FIG>. As shown, the generator <NUM> comprises a total of eight ventilation units <NUM> arranged close to the outer circumference of the generator <NUM> such that they can be connected to corresponding ducts (e.g., ducts <NUM> in <FIG>) which are in communication with corresponding outlets. Again, it is noted that any other number of ventilation units <NUM> may be used in other exemplary embodiments, such as one, two, three, four, six, <NUM> or <NUM> ventilation units <NUM>.

As shown above, both exemplary embodiments provide simple and compact structures for ejecting used generator cooling fluid through outlets formed in the interface section of the canopy. While the embodiment shown in <FIG> relies on a short tubular member adding a bit to the length of the canopy but without affecting the cross-section of the interface between canopy and generator, the embodiment shown in <FIG> avoids any axial extension by instead adding protrusions along the circumference of the interface section.

Claim 1:
A canopy (<NUM>, <NUM>) for a direct drive wind turbine, the canopy comprising an interface section (<NUM>, <NUM>) configured for mechanically coupling the canopy to a generator (<NUM>), wherein the interface section comprises at least one outlet (<NUM>, <NUM>) configured to receive cooling fluid exhausted by the generator and eject the received cooling fluid, wherein the interface section comprises a tubular member extending in the axial direction of the wind turbine.