TECHNICAL FIELD

The present invention relates to a wind turbine rotary electric machine rotor.

BACKGROUND ART

To produce electric energy using wind turbines, rotary electric machines are used to convert kinetic energy to electric energy. Part of the kinetic energy converted by the rotary electric machine is converted to heat, which must be removed to optimize efficiency of the machine. In fact, as the temperature increases, the efficiency of the rotary electric machine decreases.

The electric energy produced is subsequently transformed in phase and frequency in stationary electric machines, which are also cooled to optimize performance .

For this purpose, the wind turbines described in US 7,057,305, US 7,161,260, US 6,676,122, US 7,594,800 and EP 2,136,077 comprise air cooling systems. More specifically, EP 2,136,077 describes a wind turbine comprising a rotary electric machine; a rotary assembly with a hub; blades fitted to the hub; a nacelle supporting the rotary electric machine; and a forced-air cooling system, which feeds air successively through the hub, the rotary electric machine and the nacelle. In other words, air flows in through a first opening in the hub, and out through a second opening in the rear of the nacelle.

Air cooling systems provide for fairly good performance of rotary electric machines on wind turbines installed in relatively mild or cold climates.

In hot climates, on the other hand, liquid cooling systems are required.

US 7,168,251 Bl describes a wind turbine comprising a preferably closed-circuit, preferably liquid cooling system.

Wind turbines must often be designed and built with a cooling system designed according to the climate of where the wind turbine is installed, i.e. to maximize power and efficiency of the electric machine according to the climate at the installation site.

Designing and building wind turbines according to the climate at the installation site, the scale economies made possible by mass production of the wind turbine component parts are greatly reduced.

In this respect, known cooling systems are not particularly versatile and perform poorly as regards cooling the electric generator.

To eliminate this drawback, the Applicant's Patent

Application EP 2,354,542 proposes a rotor liquid cooling system with a tubular structure fitted with heat exchangers .

This system is highly effective and versatile, but the heat exchangers increase the weight of the rotor. DISCLOSURE OF INVENTION

It is an object of the present invention to provide a rotary electric machine rotor that can be effectively cooled by a liquid or gas or a liquid/gas mixture, and is designed to eliminate the drawbacks of the known art.

According to the present invention, there is provided a wind turbine rotary electric machine rotor, the rotor comprising a tubular structure extending and designed to rotate about an axis of rotation; a plurality of active segments parallel to and arranged about the axis of rotation and fitted to the tubular structure; and a plurality of cooling channels formed in the tubular structure .

This provides for highly effective cooling of the tubular structure, which is positioned directly contacting the active segments.

In a preferred embodiment of the present invention, each cooling channel is parallel to the axis of rotation, and extends the full axial length of the tubular structure.

In a preferred embodiment of the present invention, the tubular structure comprises a cylindrical body; the plurality of cooling channels including axial cooling channels formed in the cylindrical body.

In other words, the cylindrical body, which is preferably made of metal, is traversed by cooling channels.

The cylindrical body preferably comprises axial ribs for supporting the active segments; the cooling channels comprising cooling channels in the axial ribs.

Because the axial ribs are positioned contacting the active segments, cooling the axial ribs is especially important.

In another preferred embodiment of the present invention, the tubular structure comprises a plurality of sectors arranged about the axis of rotation; the plurality of cooling channels comprising cooling channels extending inside the sectors.

Instead of a one-piece cylindrical body, the tubular structure may comprise a plurality of adjacent sectors; in which case, the cooling channels can be formed easily in each sector.

More specifically, each sector is extruded; the cooling channels being extruded directly inside the sector .

The cooling channels can thus be formed simultaneously with the sector.

In a variation, each sector is defined by a stack of laminations with openings; each cooling channel being defined by openings aligned in a direction parallel to the axis of rotation.

In this way, the sector is also highly capable of conducting magnetic flux, and the cooling channels are aligned with one another.

In a preferred embodiment of the present invention, each sector comprises pipes housed in the cooling channels .

The pipes preferably adhere to the sector along the walls of the cooling channels.

In a preferred embodiment of the present invention, each sector has axial ribs for supporting the active segments .

Each sector is thus designed to directly support, and be positioned contacting, the active segments.

In a preferred embodiment of the present invention, in addition to cooling channels formed in the tubular structure, the rotor also comprises further cooling channels extending in an axial direction and preferably the whole length of the rotor.

In a preferred embodiment of the present invention, the further cooling channels are bounded by the tubular structure and the active segments.

Since the active segments are fitted directly to the tubular structure, the tubular structure and/or the active segments need simply be designed to define the cooling channels once the active segments are fitted to the tubular structure.

Each further cooling cannel is preferably lined with a hydroformed pipe to secure the respective active segment to the tubular structure.

The hydroformed pipe lining, on the one hand, allows liquid to be conducted inside the further cooling channel, and, on the other, provides for securing the active segment to the tubular structure.

In a preferred embodiment of the present invention, the further cooling channels extend axially and are located inside the active segments.

It is thus possible to cool the heat-generating active segment.

In a preferred embodiment of the present invention, the rotor is associated with a liquid cooling system comprising at least one rotating circuit portion extending at least partly inside the cooling channels.

The possibility of liquid-cooling the rotor improves rotor cooling capacity, especially when the cooling channels are located inside the tubular structure .

It is a further object of the present invention to provide a wind turbine designed to eliminate the drawbacks of the known art . According to the present invention, there is provided a wind turbine comprising a rotary electric machine, and a blade assembly connected to the rotary electric machine; and wherein the rotary electric machine comprises a rotor as described above.

Preferably, the rotor is connected directly to the blade assembly, to eliminate the need for a mechanical transmission.

In a preferred embodiment of the present invention, the wind turbine comprises a liquid cooling system, in turn comprising a rotating circuit portion fitted to the rotor, and a stationary circuit portion.

BRIEF DESCRIPTION OF THE DRAWINGS

A number of non-limiting embodiments of the present invention will be described by way of example with reference to the attached drawings, in which :

Figure 1 shows a view in perspective, with parts removed for clarity, of a wind turbine equipped with a rotor in -accordance with the present invention;

Figure 2 shows a partly schematic elevation, with parts removed for clarity, of a rotary electric machine equipped with the Figure. 1 rotor, and of a liquid cooling system associated with the rotor;

Figure 3 shows a larger-scale view in perspective, with parts removed for clarity, of a detail of the Figure 2 rotor; Figure 4 shows a larger-scale, partly exploded view in perspective, with parts removed for clarity, of a component of the Figure 2 rotor;

Figure 5 shows a partly sectioned side view, with parts removed for clarity, of a variation of the Figure 4 component ;

Figure 6 shows a partly exploded view in perspective, with parts removed for clarity, of the Figure 5 variation;

Figure 7 shows a partly sectioned, schematic side view, with parts removed for clarity, of a rotor in accordance with an alternative embodiment of the present invention;

Figures 8 and 9 show larger-scale, partly sectioned side views, with parts removed for clarity, of details of the Figure 9 rotor in accordance with variations of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 indicates as a whole a wind turbine for producing electric energy. Wind turbine 1 comprises a pylon 2; a nacelle 3 mounted to rotate on pylon 2; an electric machine 4 fitted to nacelle 3; and a blade assembly 5 connected to electric machine 4.

The wind turbine also comprises a liquid cooling system 6, of which Figure 1 only shows two heat exchangers 7 which, in the example shown, are fitted to the outside of nacelle 3.

In the example shown, electric machine 4 comprises a stator 8 fixed to nacelle 3; and a rotor 9, which is supported to rotate with respect to stator 8, is located inside stator 8, and is connected rigidly to, and driven directly by, blade assembly 5.

It is understood that the present invention also applies to configurations other than the one shown and described in detail, i.e. to configurations in which the rotor surrounds the stator, or in which a drive is interposed between the blade assembly and the rotor.

With reference to Figure 2, electric machine 4 is tubular and extends about an axis of rotation A.

In the example shown, stator 8 comprises a tubular structure 10; and active segments 11, which are arranged about axis of rotation A, are fitted to tubular structure 10, and extend axially. Rotor 9 comprises a tubular structure 12; a hub 13; a radial structure 14 for connecting hub 13 to tubular structure 12; and active segments 15 arranged about axis of rotation A.

In the example shown, tubular structure 12 comprises a plurality of sectors 16 arranged about axis of rotation A and substantially adjacent to one another circumferentially . Each sector 16 is fitted to radial structure 14. Rotor 9 is connected to liquid cooling system 6, which comprises a rotary circuit portion 17 and a stationary circuit portion 18. Rotor 9 actually comprises rotary circuit portion 17 of liquid cooling system 6. Liquid cooling system 6 schematically comprises a rotary liquid distributor 19 to which rotary circuit portion 17 and stationary circuit portion 18 are connected; a liquid circulating pump 20 located along stationary circuit portion 18; and at least one of heat exchangers 7 , which are also located along stationary circuit portion 18.

Liquid cooling system 6 generally comprises a plurality of rotary circuit portions 17, each associated with a respective sector 16. Each rotary circuit portion 17 comprises two, respectively liquid feed and liquid return, branches 21, which, in the example shown, extend radially at radial structure 14.

Tubular structure 12 comprises a plurality of cooling channels 22 formed in tubular structure 12 itself. In the example shown, each sector 16 has cooling channels 22 parallel to axis of rotation A. The cooling channels 22 formed in tubular structure 12 serve to conduct air, or, as in the example shown in the attached drawings, form an integral part of liquid cooling system 6. In other words, rotary circuit portion 17 is defined partly by cooling channels 22.

More specifically, and with reference to Figure 3, each sector 16 is defined by an extruded section cut to the required length, and comprises a main body 23; a plurality of cooling channels 22; ribs 24 for supporting active segments 15; and two axial guides 25 designed to form an axially-sliding joint with radial structure 14.

With reference to Figure 4, each sector 16 comprises four cooling channels 22; and five axial grooves 26 alternating with cooling channels 22.

In the example shown, cooling channels 22 are designed to conduct cooling liquid, and axial grooves 26 to conduct cooling air.

The four cooling channels 22 are connected to one another by fittings 27, and two of the cooling channels 22 are connected to branches 21 by respective fittings 28.

Alternatively, each cooling channel is connected to an inlet manifold and an outlet manifold.

Each fitting 27 comprises a plug 29 designed to seal two adjacent cooling channels 22 and a cavity 30 formed in main body 23 and connecting the two adjacent cooling channels 22.

Each fitting 28 comprises a plug 31 designed to seal a cooling channel 22, and which has an attachment 32 for connecting plug 31 to a branch 21.

With reference to Figures 5 and 6, plurality 33 indicates a sector similar to sector 16 in Figures 3 and 4, and which is designed for assembly to radial structure 14, to define tubular structure 12 (Figure 2) , and to support active segments 15. Active segments 15 are shown in more detail in Figures 5 and 6, and, in the example shown, each comprise a group of permanent magnets 34, and two magnetic guides 35 on opposite sides of the group of permanent magnets 34. Each magnetic guide 35 is defined by a pack of laminations, is prismatic, and has a portion designed to form a prismatic joint with sector 33, and to define a seat for the group of permanent magnets 34 and for a protective plate 36. Magnetic guide 35 comprises ties 37 for tightening together the pack of laminations, and is generally impregnated with resin.

In the example shown in Figures 5 and 6 , each sector 33 is also defined by a pack of laminations tightened together by ties 37, and comprises a main body 38; a plurality of cooling channels 39; ribs 40 for supporting active segments 15; and two axial guides 41 designed to form an axially-sliding joint with radial structure 14 (Figure 2) .

Each sector 33 comprises four cooling channels 39, and five axial grooves 42 alternating with cooling channels 39. Main body 38 of sector 33 and each active segment 15 form a cooling channel 43 at each groove 42. And likewise, main body 38 and each two adjacent active segments 15 define a further cooling channel 44. In general, sector 33 and active segments 15 fitted to sector 33 together define cooling channels 39 formed in sector 33, and cooling channels 43 and 44 located between sector 33 and the active segments.

Cooling channels 39, 43 and 44 form part of air cooling circuits or liquid cooling circuits.

With reference to Figure 5, the walls of cooling channels 39 may be lined with polymer material or with actual hydroformed pipes 45, which, when cooling channels 39 define rotating circuit portion 17, are connected to fittings Rl and R2 : R2 for connecting two cooling channels 39; and Rl for each connecting a cooling channel 39 to a branch 21 of rotating circuit portion 17.

Likewise, as shown in Figure 6, the other cooling channels 43 and 44 may also theoretically be lined with hydroformed pipes 45 and form part of a liquid cooling circuit .

If so, lining cooling channels 43 with hydroformed pipes provides for securing active segment 15 to tubular structure 12, and in particular to sector 33.

Number 46 in Figure 7 indicates a rotor of a tubular rotary electric machine for a preferably direct- drive wind turbine .

Rotor 46 comprises a tubular structure 47; and a plurality of active segments 48 arranged along tubular structure 47. Tubular structure 47 has a cylindrical body 49; and a plurality of ribs 50 defining axial seats for active segments 48. And each active segment 48 comprises a group of permanent magnets 51 gripped between two magnetic guides 52.

Tubular structure 47, i.e. ribs 50 and cylindrical body 49, is preferably cast in one piece, and the parts of it requiring greater dimensional accuracy subsequently machined. Tubular structure 47 also comprises axial cooling channels 53 and 54 formed in tubular structure 47 itself; and axial cooling channels 55 bounded by tubular structure 47 and active segments 48. Each cooling channel 55 is bounded by an active segment 48, by two adjacent ribs 50, and by cylindrical body 49.

Cooling channels 53, 54 and 55 form part of air or liquid cooling circuits.

Cooling channels 53 and 54 may easily be used to form rotating circuit portion 17 (Figure 2), and cooling channels 55 are designed to preferably conduct air.

Cooling channels 53 are formed, preferably cast or drilled, directly inside cylindrical body 49. Cooling channels 54 are formed the same way inside ribs 50. And cooling channels 53 and 54 may easily be connected to one another by U-shaped fittings 56, and to branches 21 by L-shaped fittings 57. Figure 8 shows a variation of the active segments 48 fitted to tubular structure 47, it being understood that the Figure 8 active segments may also be fitted to tubular structure -12, with the necessary alterations to form a prismatic joint with tubular structure 12. Active segment 48 comprises a cooling channel 58 formed in active segment 48 itself. In the example shown, cooling channel 58 is bounded by two permanent magnets 51, and more specifically by two grooves 59 in two adjacent permanent magnets 51.

Figure 9 shows a further variation of the active segments 48 fitted to tubular structure 47. Active segment 48 comprises a plurality of cooling channels 60 formed in active segment 48 itself. In the example shown, each cooling channel 60 is bounded by two permanent magnets 51 spaced apart, and by magnetic guides 52.

Clearly, changes may be made to the rotor according to the present invention without, however, departing from the scope of the accompanying Claims