WO2020250260A1

WO2020250260A1 - Conveyor for vertical axis wind generators

Info

Publication number: WO2020250260A1
Application number: PCT/IT2020/050146
Authority: WO
Inventors: Paolo Fabrizio DE MARCO
Original assignee: De Marco Paolo Fabrizio
Priority date: 2019-06-13
Filing date: 2020-06-10
Publication date: 2020-12-17
Also published as: IT201900008895A1

Abstract

The present invention refers to a conveyor for vertical axis wind generator comprising a chamber (2) adapted to contain a rotor (3) of a wind generator (30), and a plurality of channels (5) adapted to convey an airflow (11) in said chamber (2), from an external environment (6), said external environment (6) being external to the conveyor (1 ). Each channel (5) of said plurality of channels (5) comprises a curvilinear longitudinal shape. Moreover, each of said channels (5) of said plurality of channels (5) comprises an inlet opening (10) and an outlet opening (12), and the ratio between the surface extent of the inlet opening (10) and the surface extent of the outlet opening (12) e substantially higher than or equal to 4:1. The present invention also refers to a vertical axis wind generator (30) comprising a rotor (3) and a conveyor (1).

Description

TITLE

Conveyor for vertical axis wind generators

DESCRIPTION

An object of the present invention is a conveyor for wind generators, in particular for vertical axis wind turbines with Savonius rotor.

Wind generators, or wind turbines, can be divided in two categories, as a function of the position of the rotor with respect to the airflow hitting the rotor.

A first type of wind generators consists of horizontal axis wind ma chines. Such machines generally comprise three blades, operating on func tion.

A second type of wind generators consists of vertical axis wind ma chines, based on Savonius rotor or Darrieus rotor.

It is also known a hybrid category of wind machines which are capa ble of combining the advantages of Savonious-type turbines and Darrieus- type turbines. This latter type of wind machines, at low wind speeds, takes advantage of drag forces, whereas, at high speed, takes advantages of lift forces.

The horizontal axis wind turbines, due to their configuration, have the possibility to expose the entire active surface, or the most part thereof, to the airflow. That allows having a good efficiency in terms of aerodynamic yield.

However, the limit of the horizontal axis wind machines is the difficulty of self-running and operating with low speed winds (<3m/s), the latter being more frequent of fast winds.

Moreover, horizontal axis turbines are affected by the turbulence of the fluid vein and the turbulence generated by the blades, during rotation. A further limit of these machines is represented by the limit peripheral speed, defined by the term“Tip Speed Ratio”; once this limit has been overcome, the machine can achieve the self-destruction. The vertical axis machines expose all the surface of the rotor to the fluid vein. However, just one part thereof is active, in the sense that, only one part of the blade surface generates torque. The remaining part of the blade surface is in opposition to the fluid vein and contributes only to energy dissipation. This surface is known under the term“passive surface”. More over, the blades located transversally, i.e. at 90° with respect to the fluid vein does not produce work and, in some circumstances, it produces work contrary to the torque generation.

In contrast to the horizontal axis machines, the vertical axis ma chines based on Savonius rotor are not affected by the turbulence of the fluid vein. The drag-type vertical axis machines, based on Savonius rotor, however cannot be made with only one blade, as also possible in horizontal axis machines, operating with strong winds.

In order to solve the problem of the“passive surface” in the vertical axis wind turbines, particularly for those based on Savonius rotor, different technical solutions have been proposed.

For example, conveyors adapted to shield the passive surface of the machine are known. However, the passive surface of the machine does not contribute to the generation of torque.

Therefore, in the drag-type vertical axis machines the passive sur face adsorbs energy from the fluid vein in contrast to the active part, thus decreasing power useful to the system (for three-blades turbines there is a yield peak (^«29%), by increasing or decreasing this number the yield de creases).

A further problem of the vertical axis wind machine is the impossibility to use single-blade rotor as, the blade alignment to the fluid vein, would prevent in fact the rotation of the rotor.

The Applicant has now found a conveyor for wind generators, in par ticular for vertical axis wind turbines with Savonius rotor, which allows to overcome the problems above.

An object of the present invention is a conveyor for vertical axis wind generator comprising a chamber adapted to contain a rotor of a wind gen erator; a plurality of channels adapted to convey an airflow in said chamber, from an external environment, said external environment being external to the conveyor; wherein each channel of said plurality of channels comprises a curvilinear longitudinal shape, each of said channels of said plurality of channels comprising an inlet opening and an outlet opening, and the ratio between the surface extent of the inlet opening and the surface extent of the outlet opening being substantially higher than or equal to 4:1 .

Advantageously, the conveyor object of the present invention, allows to shield the passive surface of the wind machine and simultaneously, to make active the upwind rotating blade surface.

More in particular, the conveyor object of the present invention allows making active the machine portion rotating upwind, i.e. making active the passive part of the same machine, recovering energy otherwise lost. In this way, the contribution to the torque generation, which in the vertical axis wind machines is negative, is made positive.

Another advantage of the present invention is to increase the blade number of the rotor, resulting to be simultaneously engaged.

A further advantage of the conveyor object of the present invention is to allow the use of a one-blade vertical axis wind machine.

According to a preferred aspect, said plurality of channels comprises at least four channels, more preferably six channels.

According to a preferred aspect, each channel of said plurality of channels has a continuous curvilinear longitudinal shape along the whole length of longitudinal extension of the channel.

According to another preferred aspect, at least one channel of said plurality of channels has a length L1 and at least one channel of said plural ity of channels has a length L2, wherein length L1 is higher than length L2.

According to a further preferred aspect, each of said channels of said plurality of channels, comprises an inlet opening and an outlet opening; wherein said inlet opening is adapted to allow the entrance of an airflow in said channel, from said external environment; wherein said outlet opening is adapted to allow the leaving of said airflow from said channel and the entrance of said airflow in said chamber; the inlet openings of said plurality of channels being aligned along a same direction with respect to the con veyor; and/or said inlet openings of said plurality of channels, having a sur face extent higher than or equal to the surface extent of said outlet openings of said plurality of channels.

According to another preferred aspect, the ratio between the surface extent of the inlet opening and the surface extent of the outlet opening e higher than or equal to 2:1 , preferably e equal to 4:1 .

Preferably, the conveyor for vertical axis wind generator comprises a bottom opening and a top opening adapted to convey an airflow, from said chamber, in said external environment, wherein said bottom opening and said top opening are located at opposite ends of the chamber.

According to another aspect, the conveyor can comprise a plurality of ducts, delimiting said channels, and a wall delimiting said chamber, wherein said ducts and/or said wall comprising a material which is transpar ent to the light.

According to a further preferred aspect, each channel of said plurality of channels comprises an inlet opening and an outlet opening; wherein said inlet opening is adapted to allow the entrance of an airflow in said channel, from said external environment; wherein said outlet opening is adapted to allow the leaving of said airflow from said channel and the entrance of said airflow in said chamber; wherein said outlet openings are symmetrically lo cated with respect to a longitudinal symmetry axis of the chamber.

According to another aspect, the chamber adapted to integrally con tain a rotor of a wind generator.

In another aspect, each channel of said plurality of channels com prises a first portion having a substantially convergent conformation, the first portion corresponding to the inlet portion of the airflow into the channel, and a second portion having a substantially divergent conformation, said second portion being located downstream of said first portion.

According to another aspect, each channel comprises a third portion having a transversal section substantially constant, said third portion being located downstream of said second portion.

In another aspect, each channel comprises a fourth portion corre sponding to a portion for the leaving of the airflow from the channel and from which the airflow can enter in the chamber, said fourth portion being located downstream of said third portion.

According to another aspect, the fourth portion has a substantially convergent conformation having preferably a convergence higher than or equal to 1 °, more preferably equal to 5° with respect to a longitudinal sym metry axis of the channel.

In another aspect, the longitudinal length of the first portion is sub stantially equal to 2 times the longitudinal length of the third portion and wherein the longitudinal length of the second portion is substantially equal to 6 times the longitudinal length of the third portion.

In another aspect, the second portion comprises a central portion having a maximum surface transversal extent substantially equal to 2 times the surface extent of the outlet opening of the channel.

A second object of the present invention comprises a vertical axis wind generator comprising a rotor and the conveyor as defined above, wherein said rotor is contained in the chamber of said conveyor; and wherein said conveyor is pivoted to said wind generator such that the rota tion of the conveyor is independent from rotor rotation.

These and further objects, which will be more evident from the fol lowing description, are achieved by the conveyor for vertical axis wind gen erators of the present invention, which is described below, in a preferred embodiment, non-limiting of further developments of the scope of the inven tion, by means of the attached drawings which illustrate the following fig ures: Fig. 1 , a sectional view of the conveyor object of the present inven tion, applied to a seven-blades type vertical axis wind generator;

Fig. 2, a sectional view of the conveyor object of the present inven tion, applied to a six-blades type vertical axis wind generator;

Fig. 3, a sectional view of the conveyor object of the present inven tion, applied to a five-blades type vertical axis wind generator;

Fig. 4, a sectional view of the conveyor object of the present inven tion, applied to a four-blades type vertical axis wind generator;

Fig. 5, a sectional view of the conveyor object of the present inven tion, applied to a three-blades type vertical axis wind generator;

Fig. 6, a sectional view of the conveyor object of the present inven tion, applied to a two-blade type vertical axis wind generator;

Fig. 7, a sectional view of the conveyor object of the present inven tion, applied to a one-blade vertical axis wind generator;

Fig. 8, an axonometric view of the conveyor object of the present in vention;

Fig. 9, an exploded axonometric view of the conveyor of figure eight and of a vertical axis wind generator;

Fig. 10, an axonometric view of the conveyor applied to a wind gen erator;

Fig. 1 1 , a plan view of the conveyor support profile;

Fig. 12, a sectional side view of the conveyor support profile and a group of support bearing;

Fig. 13, a sectional side view of the conveyor support profile, in a second embodiment, and of a group of support bearing;

Fig. 14, a plan view of a channel of the conveyor according to a fur ther aspect of the present invention.

The conveyor for vertical axis wind generators is indicated as a whole with the reference number 1 . Hereinafter, in the present description, the conveyor for vertical axis wind generator, for the sake of brevity, is named with the term conveyor. The expression vertical axis wind generator indicates a vertical axis wind turbine of known-type, for example a Savonius-type wind turbine. The applicability of conveyor 1 , object of the present invention, however is not limited to wind turbines of Savonius-type or Darrieius-type.

With reference to figures attached, the conveyor 1 comprises a chamber 2 adapted to contain a rotor 3 of a wind generator 30 and a plurality of channels 5, adapted to convey an airflow 1 1 in said chamber 2, from an external environment 6 al conveyor 1 .

Preferably, the chamber 2 adapted to integrally contain a rotor 3 of a wind generator 30.

According to a preferred aspect of the invention, the conveyor 1 com prises a wall 4, having a shape preferably cylindrical. Said wall 4 delimits the chamber 2 i.e., the chamber 2 is defined and delimited, in the external perimeter thereof, from said wall 4. The wall 4 can comprise a bottom open ing 7 and a top opening 8, both having preferably a transversal section of circular shape. Said bottom 7 and top 8 openings allows to the airflow 1 1 , to leave the chamber from the chamber 2 and enter in the external environ ment 6.

Said bottom 7 and top 8 openings are preferably positioned in corre spondence of the opposite ends of the wall 4, i.e. of the chamber 2. Such configuration increases the available outer surface 40, of the wall 4 per the channels 5. In other words, the wall 4 is wholly usable to let an airflow 1 1 to enter the chamber 2, through a plurality of channels 5. Accordingly, due to the position of the bottom 7 and top 8 openings, an increase of the airflow 1 1 is obtained, that can be convoyed through the channels 5, in said cham ber 2. For the presence of the bottom 7 and top 8 openings, the wall 4 has a substantially hollow shape, preferably tubular, i.e. having an opening passing a section preferably circular, corresponding to the chamber 2. Fur thermore, the bottom 7 and top 8 openings allows introducing the rotor 3, of a wind generator 30, in said chamber 2. To that end, the chamber 2 can be sized to integrally contain a rotor 3 of a wind turbine 30. In a preferred aspect of the present invention, the chamber 2 has a cylindrical shape, a circular base, preferably having a diameter higher than the maximum outer diameter of the rotor 3. Accordingly, when the conveyor 1 is applied to a wind generator 30, the rotor 3, when hit by an airflow 1 1 , has the possibility to rotate independently with respect to the conveyor 1 . In other words, the rotor 3 can rotate with a certain rate, with respect to the inner surface inner surface 41 of the wall 4. The total longitudinal length of the chamber 2 is preferably higher than or equal to the total longitudinal length of the rotor 3. In a preferred aspect, the total longitudinal length of the chamber 2 corresponds to the distance between the bottom opening 7 and the top opening 8.

The wall 4 can be made of one of the following materials: metal alloy, for example aluminum alloy, composite material, polymer material. In a pre ferred aspect, the wall 4 is made of a material, which is transparent to the light. For example, the wall 4 can be made of transparent polycarbonate. Advantageously, the use of a transparent material allows reducing the visual impact of the conveyor.

With reference to figures 1 -7, the conveyor 1 comprises a plurality of channels 5. Said channels 5 are adapted to convey an airflow 1 1 , from the external environment 6 to the conveyor 1 , in said chamber 2.

In an embodiment, the conveyor 1 can comprise a couple of channels 5. In another embodiment, the conveyor 1 can comprise three, four, five, six or more channels 5. Preferably, the conveyor 1 comprises at least four channels 5. Even more preferably, the conveyor 1 comprises six channels 5, as illustrated in figures 1 -7.

According to a preferred aspect, each channel 5 is delimited by a duct 9. Preferably, each duct 9 comprises a through longitudinal cavity, cor responding to the channel 5. Preferably, each duct 9 is connected to the outer surface 40 of the wall 4. According to an alternative preferred form, each duct 9 can extent, seamless, from the outer surface 40 of the wall 4 of the conveyor 1 , as evident from figures 1 -10. Preferably, in such configura tion, the plurality of ducts 9 and the wall 4 constitute a unique body.

Preferably, in both the configurations described above, the chamber 2 and the plurality of channels 5 are in a seemless fluid-dynamic connection. Therefore, the channels 5 allow to convey an airflow 1 1 , from an external environment 6 to the conveyor 1 , in said chamber 2. In operation, said chamber 2 contains a rotor 3 of a wind generator 30. The airflow 1 1 , entered in said chamber 2 through the channels 5, allows driving the rotor 3.

With reference to figures 1 -7, each duct 9 delimits and defines each channel 5. Each channel 5 comprises an inlet opening 10, which corre sponds to a inlet opening 90 of the duct 9. Said inlet opening 10 is com municating with the external environment 6 to the conveyor 1 . In operation, the inlet opening 10 allows the conveyor to convey an airflow 1 1 , from an external environment 6, into the channel 5.

Each channel 5 comprises an outlet opening 12, corresponding to an outlet opening 92 of the duct 9. The outlet opening 12 allows the leaving of an airflow 1 1 , from said channel 5, and the input of the same airflow 1 1 , in the chamber 2.

With reference to figures 1 -7, each channel 5, and consequently each duct 9, comprises a curvilinear longitudinal shape. In other words, each channel 5 and then each duct 9, extent according to a curvilinear longitudi nal direction, starting from the chamber 2, towards the external environment 6. In such configuration, each channel 5 can also comprise linear portions, alternating to curvilinear portion.

In a further aspect, each channel 5 can also have a continuous cur vilinear conformation, i.e. curvilinear along the whole length or curvilinear abscissa of the channel 5. In such configuration, each channel 5 does not comprise linear portions or discontinuity, the latter alternating to the curvi linear portion(s). In other words, the channels 5 maintain a continuous cur vilinear shape, from the respective inlet openings inlet openings 10, up to the respective outlet openings 12. Such configuration allows reducing load losses, which happen with the passage of the airflow 1 1 , in the channels 5.

The plurality of channels 5 is configured such that each channel 5 can extent from a different point of the wall 4, i.e. of the chamber 2. Prefer ably, said point corresponds to the outlet opening 12 of each channel 5. Starting from the above said point, the channels 5 extent preferably accord ing to a curvilinear direction, in the same direction and in the same orienta tion, as evident for example from figure 1 .

In a different preferred embodiment, the outlet openings 12 of each channel 5, i.e. the points from which the channels 5 extents, can be sym metrically located around the chamber 2. In other words, the channels 5, i.e. ducts 9, can extents from a plurality of points of chamber 2, symmetrically connected with respect to the center of the chamber 2 or symmetrically con nected with respect to longitudinal symmetry axis of the chamber 2.

In a different aspect, the above said point of the chamber 2, from which the channels 5 extent, can be connected also not symmetrically, with respect to the chamber 2.

The inlet openings 10, i.e. the inlet openings 90 of the ducts 9, are oriented preferably in a same direction, with respect to the conveyor 1 . How ever, the direction of one or the direction of one or more inlet openings 10 can range between 0 and 90°, with respect to the direction of orientation of the remaining inlet openings 10.

More in particular, the channels 5, i.e. the ducts 9, can be conformed according to a curvilinear direction of longitudinal extension in such that the inlet openings 10 are substantially oriented, i.e. aligned, according to same direction, with respect to the conveyor 1 . In such a way, the inlet openings 10 can convey into the channels 5 an airflow 1 1 hitting the conveyor 1 , hav ing a main direction and an orientation opposite to the orientation of exten sion the channels 5, i.e. of the ducts 9.

In a different embodiment, the longitudinal conformation of the chan nels 5, i.e. of the ducts 9, can be curvilinear, more in particular arc-shaped, with a radius ranging along the direction of longitudinal extension. Alterna tively, the longitudinal conformation of the channels 5, i.e. of the ducts 9, can be curvilinear, more in particular arc of a circle, with a constant radius.

In operation, i.e. when the conveyor 1 is applied to a wind generator 30, the curvilinear conformation of the channels 5 allows conveying an air flow 1 1 , external to the conveyor 1 , and having a main direction, in said chamber 2. More in particular, the channels 5, i.e. the ducts 9, are con formed to convey airflow 1 1 , from the external environment 6, in a different point of the chamber 2. The latter, corresponds to the point wherein, for each channel 5, the outlet opening 12 is located, as evident for example from figure 7. When the conveyor 1 is hit by an airflow 1 1 , such airflow 1 1 enters into each channel 5, through the respective inlet opening 10 or inlet opening 90. Thought each channel 5, the airflow 1 1 is conveyed and orien tated towards the respective outlet opening 12 or outlet opening 92, of the duct 9. From each outlet opening 12, the airflow enters into the chamber 2 where, in operation, the rotor 3 of a wind generator 30 is located. For the curvilinear longitudinal shape of the channels 5, i.e. of the ducts 9, the flow 1 1 is conveyed in different points of the chamber 2, corresponding to the position of each outlet opening 12. The curvilinear longitudinal shape of the channels 5, allows the airflow 1 1 to enter into the chamber 2, along a direc tion coincident with an optimal incidence direction of the blades of the rotor 3.

With reference to figures 1 -7, also the outlet openings 12 are con formed such that the airflow 1 1 , entering in the chamber 2 from each chan nel 5, is directed substantially in a concordant circular direction. In such way, the airflow 1 1 , entered in the chamber 2 from each channel 5, results in an airflow internal to the chamber 2, rotating in a direction of concordant rota tion, clockwise or counterclockwise. Once exchanged work with the rotor 3, the airflow 1 1 enters again in the external environment 6, through the bottom 7 and top 8 openings of the chamber 2. In another preferred aspect, each channel 5 comprises a substan- tially-rectangular transversal section. The extent of the transversal section of the channel 5 is, however sized such that the airflow 1 1 to be convoyed along the whole length of the rotor 3. The surface extent, corresponding to the area of the transversal section of each channel 5, can be constant or ranging along the longitudinal extension direction of the channel 5. In this latter case, the channel 5 ad, accordingly, the duct 9 have a convergent configuration, starting from the inlet section 10, towards the outlet section 12. Such configuration allows increasing the inlet airflow speed in the cham ber 2.

In another aspect, the surface extent of the inlet opening 10 can be higher than the surface extent of the outlet opening 12. For example, the ratio between the surface extent of the inlet opening 10 and the surface extent of the outlet opening 12 can be preferably higher than or equal to 2:1 , even more preferably substantially higher than equal to 4:1 .

Figure 14 illustrates a channel 5 of the conveyor 1 according to a further embodiment of the present invention. In such embodiment, the con veyor 1 comprises a plurality of channels 5, each having a substantially cur vilinear conformation as illustrated in figure 14. In the same figure 14, a channel 5 having a linear conformation is illustrated for exemplary purpose only. Therefore, the channels 5 comprise a substantially curvilinear confor mation.

According to the embodiment illustrated in figure 14, the channel 5 can comprise an inlet opening 10 and an outlet opening 12. The ratio be tween the surface extent of the inlet opening 10 and the surface extent of the outlet opening 12 e substantially higher than or equal to 4:1 .

As illustrated in figure 14, the channel 5 can be preferably divided into 4 portions. A first portion 50 correspond to the inlet portion in the chan nel 5, namely the portion through which the airflow enters from the external environment into the channel 5. The first portion 50 can comprise a sub- stantially convergent conformation. Preferably, the ratio between the sur face extent of the inlet opening 500, the latter corresponding to the inlet opening 10 of the channel 5, and the surface extent of the outlet opening 502 of the first portion 50 is substantially equal to 4:1 . In other words, the surface of the inlet opening 10 is 4 times the surface of the outlet opening 502 of the first portion 50. The first portion 50 can preferably have a longi tudinal length equal to 2 times the longitudinal length of a third portion 52 of the channel 5 which will be described below. The height of the first portion 50 is preferably substantially equal to the height of the chamber 2.

The channel 5 can comprise a second portion 51 having a substan tially divergent conformation. The second portion 51 is located downstream of said first portion 50. The second portion 51 can comprise an inlet opening 510, the latter corresponding to the outlet opening 502 of the first portion 50, and an outlet opening 512. The second portion 51 can have a confor mation initially divergent and then convergent, as illustrated in figure 14, such that to connect to a third portion 52 of the channel 5 at the outlet open ing 512. The maximum transversal surface extent of the second portion 51 can be substantially equal to 2 times the surface extent of the outlet opening 12 of the channel 5. Finally, the height of the second portion 51 is substan tially equal to the height of the chamber 2. The second portion 51 of the channel 5 can have a longitudinal length substantially equal to six times the longitudinal length of the third portion 52.

With reference to figure 14, the channel 5 can comprise a third por tion 52 having a transversal section substantially constant. The third portion 52 is located downstream of said second portion 51 . The third portion 52 comprises an inlet opening 520 corresponding to the outlet opening 512 of the second portion 51 , and an outlet opening 522. The height of the third portion 52 is substantially equal to the height of the chamber 2.

Finally, the channel 5 can comprise a fourth portion 53 corresponding to a portion for the leaving of the airflow from the channel 5 and from which the airflow can enter in the chamber 2. The fourth portion 53 is located downstream of said third portion 52. The fourth portion 53 comprises an inlet opening 530 corresponding to the outlet opening 522 of the third portion 52, and an outlet opening 532 corresponding to the outlet opening 12 of the channel 5. The fourth portion 53 can have a substantially convergent con formation having preferably a convergence higher than or equal to 1 °, more preferably equal to 5° with respect to a longitudinal symmetry axis of the channel 5. The height of the third portion 53 is substantially equal to the height of the chamber 2.

The configuration of the channel 5 described above allows increasing the airflow entered from the external environment 6 into the chamber 2. Fur thermore, the configuration illustrated in figure 14, allows increasing the leaving rate of the airflow from the channel 5, the latter corresponding to the input rate of the airflow in the chamber 2. The configuration as illustrated in figure 14 e particularly advantageous for the perimeter channels 5 having a higher longitudinal length. In particular, by adopting the above described conformation, an input rate in the chamber 2 substantially, which is the same for each channel 5, i.e. both for the channels 5 having a lower longi tudinal length (inner channels), and for the perimeter channels 5 (outer channels), the latter having a higher longitudinal length, is obtained.

In figures 1 -7, a conveyor 1 according to an aspect of the present invention is illustrated, comprising six channels 5. Said channels 5 can ex tent from different points of the chamber 2, symmetrical or not symmetrical with respect to the chamber 2. The six channels 5 can extent according to curvilinear longitudinal directions. For example, the plurality of channels 5 comprises a couple of back channels 5a, 5b, and four frontal channels 5c, 5d, 5e, 5f, interposed between said back channels 5a, 5b.

The back channels 5a, 5b can have a length of longitudinal extension L1 higher than the length of longitudinal extension L2, of said frontal chan nels 5c, 5d, 5e, 5f. In such way, the inlet openings 10 of each channel 5, are located at the same distance from the center of symmetry of the con veyor 1 . The inlet openings 10 of the channels 5 can also be oriented, i.e. aligned, in the same direction.

In another preferred aspect, the channels 5 can have symmetric con figuration with respect to a symmetry axis of the conveyor 1. For example, the back channels 5a and 5b can be symmetric and specular from each other, with respect to a symmetry axis passing for the center of the chamber 2. Similarly, the central channels 5c, 5d, can be specular and symmetric with respect to a symmetry axis passing for the center of the chamber 2 and, however, interposed between the back channels 5a and 5b.

The conveyor 1 can be applied to a vertical wind generator 30, having a rotor 3 one-blade or multi-blade. Preferably, when a vertical axis wind generator 30, comprising a rotor 3, e provided with the conveyor 1 , the rotor 3 is contained in the chamber 2 of the conveyor 1 . Preferably, the rotor 3 is integrally contained in said chamber 2.

With reference to figures 1 -7, the conveyor 1 object of the present invention, applied to a wind generator 30, with one-blade (figure 7), two- blades (figure 6), three-blades (figure 5), four-blades (figure 4), five-blades (figure 3), six-blades (figure 2) and seven-blades (figure 1 ) rotor, respec tively, is illustrated.

Preferably, the conveyor 1 allows making a vertical axis wind ma chine, one-blade configuration not obtainable in the absence of the con veyor 1 .

The advantages of the one-blade machines are of purely economic and aerodynamic nature, the same are used under high windy conditions.

In case of vertical axis one-blade machine, the calculation algorithm is considerably simplified, and the power depends on the surface of the sin gle blade.

A one-blade machine needs of an inert mass (flywheel) necessary to overcome the dead point between inlet opening and the subsequent and a counterweight to balance forces acting on the axis, such as for example the centrifugal forces.

As far as the behavior of the fluid on the conveyor is concerned, the fluid molecules hit the walls of the conveyor and cede, at the same time, kinetic energy, losing speed. Molecules of both the machine sides, since they have to achieve the blade at the same time to generate torque, the adoption of convergent ducts allows to accelerate the fluid vein to higher speeds than the inlet one (in accordance with the mass conservation prin ciple).

With this solution, a considerable increase of machine power occurs, as the outlet speed is higher than the inlet speed (in fact, according the Betz’s theory of the flow tube, the machine acquires energy as a function of , while the torque as a function of the force

and then V² .

The speed increase is due to the mass conservation principle, which imposes the regularity of the flow rate in a rigid duct (the amount of entering fluid corresponds to the leaving one), and, since the duct has sections of variable sizes, it is forced to adapt the fluid speed in the several sections or increasing pressure in the duct.

Said“S” the generic sections of the duct,“V” the speeds, and Q the flow rate crossing the duct can be written as:

Q = S_X V_X = Sy Vy

That imposes the constancy of the flow rate in the incompressible fluids, while events of pressure and speed increase simultaneously occurs in gases.

In operation, the conveyor 1 is pivoted to the wind generator 30, such that the rotation of the conveyor 1 is independent from the rotation of the rotor 3. For this aim, the conveyor 1 can comprise means 13 adapted to engage the conveyor 1 , pivotally, ad a vertical axis wind generator 30. Said means 13 can be configured such that the conveyor 1 can independently rotate with respect to the rotor 3.

According to another preferred aspect, the means 13 comprise a pro file 14. The profile 14 comprises preferably a annular-shape. The profile 14 is rigidly joined to a bottom edge 42 of the wall 4.

According a further aspect, the profile 14 can comprise a L-shaped transversal section (figure 13) or a T-shape transversal section (figure 12). In both the configurations, the profile 14 can also comprise an cylindrical outer surface 140.

In a preferred aspect, the profile 14 is constrainable, in a sliding way, to three groups of bearings 16a, 16b, and 16c. More in detail, the profile 14 is constrainable to said three groups pf bearings 16, so as to have just one degree of freedom. In such configuration, the profile 14 and, accordingly, the conveyor 1 , can rotate with respect to a symmetry axis, passing through the center of the profile 14.

With reference to figures 12 and 13, the three groups of bearings 16a, 16b, and 16c are rigidly joined to a second support structure 17. The latter being rigidly constrainable to the wind generator 30, in particular to a support frame of the wind generator 30, not illustrated in the figures at tached. In particular, when the annular profile 14 is joined to the three groups of bearings 16a, 16b and 16c, the rotation axis of the rotor 3 of the wind generator 30 is corresponding to the rotation axis of the conveyor 1 , the latter passing preferably, through the center of the chamber 2.

In another preferred aspect, the groups of bearings 16a, 16b and 16c are three and are preferably located in a symmetric position with respect to the support structure 17. For example, the three groups of bearings 16a, 16 and 16c can be placed at 120° from each other, with respect to the center of the profile 14, as evident from figure 1 1 .

In another preferred aspect, the support structure 17 is configurable to allow the regulation of bearing distances 16, in order to guarantee the rate recover existing between the conveyor 1 and the support structure 17.

According to a further preferred aspect, each group of bearing 16a, 16b and 16c can comprise further three bearings, which are distinct and separated 18a, 18b, 18c, for a total nine bearings. With reference to figures 12 and 13, the rotation axis of a couple of bearing 18a and 18b, are prefer ably parallel from each other. In such a way, the couple of bearings 18a and 18b is contacted with two parallel and opposite surfaces 141 a and 141 b of the profile 14. The third bearing 18c comprises a rotation axis which is per pendicular to the rotation axis of the couple of bearings 18a and 18b, in so that said bearing 18c rotates while contacting a cylindrical inner surface 142 of the profile 14. In such configuration, the three groups of bearings are positioned from each other at 120° with respect to the rotation axis of the profile 14. Such configuration allows supporting both horizontal pushes and overturn pushes, due to wind action on the conveyor 1 . Moreover, such ar rangement configuration of the bearings 18, allows avoiding the connection of the conveyor 1 , to the axis of the rotor 3 of the wind machine 30, at the central portion of the rotor 3. Advantageously, the conveyor 1 can be ac cordingly installed on preexisting wind machine, which are not arranged to accept a coupling of the conveyor 1 with the central axis.

The conveyor 1 allows increasing the power produced by a wind ma chine. More in detail, the conveyor 1 allows increasing the yield of a wind generator, to which the conveyor 1 is applied. Such scope is achieved by shielding the passive portion of the wind machine, i.e. containing preferably integrally the rotor 3 within the chamber 2.

Moreover, the conveyor 1 allows making active the passive portion of the wind machine 30, increasing the number of blades which are simul taneously active. Such scope is achieved by a plurality of ducts 5, having a circular longitudinal conformation and shaped to convey an airflow from an environment 6, which is external to the conveyor 1 , in the chamber 2.

As known, the maximum efficiency for wind machines based on the Savonius rotor is obtained with a number of blades which is equal to 3 (three); the increase or the decrease of the above said number leads to a performance decrease.

The present invention allows increasing the number of blades, which are simultaneously active in the wind generator. The increase of the number of blade of the rotor 3, increase the total blade surface. An increase of the number of blades also causes an increase of the torque provided and a resulting increase of power provided by the wind machine. Otherwise, in the wind machine of known type occurs a decrease of the same, as occurring in the vertical axis wind generators, without a conveyor. Such problem is due to the countercurrent blades.

By adding the conveyor 1 to the machine and maintaining unchanged the blade number, and then the total surface, the same advantages can be obtained, but in a smaller amount. The conveyor 1 object of the present invention allows obtaining a rising of the aerodynamic yield level of the sys tem.

In particular, the increase of the number of active blades, improves machine performances, as the active surface of the rotor increases, accord ing to Betz theory, hereinafter adapted to a machine provided with a con veyor 1 :

wherein:

W = obtainable power according to Betz theory;

16/27 = Betz limit ^¾ 60% Y ⁼ scaling coefficient, considers the aerodynamic losses taking into ac count the aerodynamic losses within the machine and to the machine (fluid leakage between the several blades)

P ⁼ motor fluid density (variable with pressure and temperature, about 1 .21 kg/m³)

Ar = surface area of the examined blade (then the increase of the number of blades)

å* Co · sin(ct_n) =summation of the“positive Drag coefficient” times the sine of the angle assumed with respect to the fluid vein, the force is maximum at 90°

åi o - sin(ct_n) =summation of the“negative Drag coefficient” times the sine of the angle assumed with respect to the fluid vein, the force is maxi mum for an angle of 90°

u) R = blades rotation speed (radiants per second times the blade radius) V^{3 =} cubed speed of the fluid vein according to the Betz theory.

From the above said formula, it results that the yield of machines op erating in such conditions is rather low. In fact, by substituting some real value [2-blades machines arranged at 180°, with C+D = 2.3 and C-D = 1 .2, it is obtained a wind yield equal to:

This yield value can be easily found in literature. By applying the con veyor according to the present invention to the wind machine, all the blades are simultaneously hit by the airflow, thus obtaining the above cited ad vantages.

Indeed, the conveyor is capable of making active the blades that travel towards and countercurrently deviating the fluid vein flow through the openings to a plurality of di inlet openings 10. Through the latter, the airflow is convoyed in a plurality of channels and then in a chamber 2, integrally containing the rotor 3 of the wind machine. The input of the airflow in said chamber takes place by suitable outlet openings 12 communicating with the chamber 2 and suitably positioning in said chamber 2. In other words, the airflow is suitably deviated by said plurality of curvilinear channels, so as to make active also the machine blades, whose rotation configuration is paral lel and opposite with respect to the fluid vein flow and then not activable.

Otherwise, the present invention allows to the entirety of the blades pale to rotate within the conveyor 1 . The blades travel with a rate sufficient to create the pressure difference between intrados and extrados. In partic ular, the blades have to be concave in order to maximize the thrust obtained from the fluid vein

= 2. 3) thus minimizing at the same time the thrusts in the counter-flow short portion (C^ = 1. 2), since the blade receives on the concave part the thrust due to fluid deviation, however the convex part is immerged in the slipstream of the previous blade which is partially or totally closed by the atmospheric pressure. In brief, the blade, in the convex part thereof, has to cut through the air in front of it, thus receiving the lowest opposition.

The inlet openings 10 allow conveying all the frontal flow on the ma chine active part, i.e. the part of the turbine which is generally passive, namely that part that normally travels countercurrent, see the fluid vein de viated of an angle such that allowing to act on the active side of the blade.

The finding allows the machine to simultaneously activate all the blades, thus exactly extracting the value of 16/27 of the energy to the fluid vein (according to the Bertz limit).

The fluid drainage, which is at this point processed, occurs with an angle of 90° with respect to the inlet in the two directions. Draining the fluid in this way, a continuous replacement of the same occurs during the rotation of the rotor, and an increase of energy extracted by the fluid vein occurs (according to physical laws, in a fluid machine the power is proportional to the amount of fluid processed in a unit of time).

In brief, this part of the finding allows to eliminate the part related to the negative coefficient:

Whose terms become positive (active blase) since the fluid is conveyed on the concave wall of the blade, thus transforming the preceding formula into:

The fluid vein deviation impose a loss of part of energy as a function of the cosine of the angle assumed.

The above said loss in the incompressible fluids is unitary (all the energy is lost) for fluid vein deviation angles equal to 180° (indeed cos(180)= -1 ), that is not true in the compressible one (see blade center of the Savonius rotor).

The conveyor 1 force a certain fluid flow rate (Q

captured by the inlet openings 10, and crossing the machine thus ceding energy to the same due to collisions on blades and the conveyor itself.

The crossing occurs through the frontal area (A_n[m²]) of each inlet opening 10, then

n An—— ^# h^< i 1 ^vn wherein the terms are the frontal area of the umpteenth inlet opening, height and width thereof, respectively.

Said p[

the working fluid density, the power available to the inlet openings can be calculated as:

Such power would not be available in a machine not provided with a conveyor, since the most part of the fluid would get away from the blades without transferring its energy.

The conveyor 1 is configured to rotate on itself, maintain the inlet openings 10 of channels 5, i.e. the inlet openings 90 of the ducts 9, aligned to the direction of the airflow 1 1 that, in operation, hits the conveyor 1 . For this aim, the conveyor 1 can be provided with means adapted to oriented, i.e. aligning the conveyor 1 to an airflow 1 1 .

In a preferred embodiment, said means consists of a rudder (not il lustrated), rigidly constrained at the ends or the upper end-edge 43 of the wall 4. The use of such rudder, allows maintaining the inlet openings 10 of the conveyor 1 , aligned to the airflow 1 1 hitting the conveyor.

Reference numbers

1 Conveyor

2 Chamber

3 Rotor

4 Wall

40 Outer surface

41 Inner surface

42 bottom edge of the chamber

43 Top edge of the chamber

5, 5a, 5b, 5c, 5d, 5e, 5f channels

6 external environment al conveyor

7 top opening wall

8 top opening wall

9 ducts

90 inlet opening

92 outlet opening

10 inlet opening

1 1 airflow

12 outlet opening

13 means adapted to pivotally constrained the conveyor to a wind generator

14 profile

16 bearing group

17 support structure

18 bearing

30 wind generator

Claims

1 ) Conveyor (1 ) for vertical axis wind generator comprising:

a chamber (2) adapted to contain a rotor (3) of a wind generator (30); a plurality of channels (5) adapted to convey an airflow (1 1 ) in said chamber (2), from an external environment (6), said external environment (6) being external to the conveyor (1 );

wherein each channel (5) of said plurality of channels (5) comprises a curvilinear longitudinal shape;

each of said channels (5) of said plurality of channels (5) comprising an inlet opening (10) and an outlet opening (12), and

the ratio between the surface extent of the inlet opening (10) and the surface extent of the outlet opening (12) being substantially higher than or equal to 4:1 . 2) Conveyor (1 ) for vertical axis wind generator according to claim 1 , wherein said plurality of channels (5) comprises at least four channels, pref erably said plurality of channels (5) comprises six channels.

3) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, wherein said curvilinear longitudinal shape is continuous along the whole length of longitudinal extension of the channel (5).

4) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, wherein at least one channel (5) of said plurality of chan nels (5) has a length (L1 ), and wherein at least one channel (5) of said plu rality of channels (5) has a length (L2), wherein the length (L1 ) is higher than the length (L2).

5) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, wherein each of said channels (5) of said plurality of chan nels (5) comprises an inlet opening (10) and an outlet opening (12);

wherein said inlet opening (10) is adapted to allow the entrance of an airflow (1 1 ) in said channel (5), from said external environment (6);

wherein said outlet opening (12) is adapted to allow said airflow (1 1 ) to leave said channel (5) and the input of said airflow (1 1 ) in said chamber (2) ;

the inlet openings (10) of said plurality of channels (5) being aligned along a same direction with respect to the conveyor (1 ); and/or

the inlet openings (10) of said plurality of channels (5), having a sur face extent higher than or equal to the surface extent of said outlet openings (12) of said plurality of channels (5). 6) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, comprising a bottom opening (7) and a top opening (8) adapted to convey an airflow (1 1 ) from said chamber (2), in said external environment (6), wherein said bottom opening (7) and said top opening (8) are located at opposite ends of the chamber (2). 7) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, wherein said chamber (2) is adapted to integrally contain a rotor (3) of a wind generator (30).

8) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, wherein each channel (5) of said plurality of channels said channels (5) comprises an inlet opening (10) and an outlet opening (12); wherein said inlet opening (10) is adapted to allow the entrance of an airflow (1 1 ) in said channel (5), from said external environment (6);

wherein said outlet opening (12) is adapted to allow the leaving of said airflow (1 1 ) from said channel (5) and the input of said airflow (1 1 ) in said chamber (2);

wherein the outlet openings (12) of said plurality of channels (5) are symmetrically located with respect to a longitudinal symmetry axis of the chamber (2).

9) Conveyor (1 ) for vertical axis wind generator according to any one of the preceding claims, wherein each channel (5) comprises a first portion (50) having a substantially convergent conformation, the first portion (50) corre sponding to the inlet portion of the airflow into the channel (5), and

a second portion (51 ) having a substantially divergent conformation, said second portion (51 ) being located downstream of said first portion (50). 10) Conveyor (1 ) for vertical axis wind generator according to claim 9, wherein each channel (5) comprises a third portion (52) having a transversal section substantially constant, said third portion (52) being located down stream of said second portion (51 ).

1 1 ) Conveyor (1 ) for vertical axis wind generator according to claim 9 or 10, wherein each channel (5) comprises a fourth portion (53) corresponding to a portion for the leaving of the airflow from the channel (5) and from which the airflow can enter in the chamber (2), said fourth portion (53) being lo- cated downstream of said third portion (52).

12) Conveyor (1 ) for vertical axis wind generator according to claim 1 1 , wherein the fourth portion (53) has a substantially convergent conformation having preferably a convergence higher than or equal to 1 °, more preferably equal to 5° with respect to a longitudinal symmetry axis of the channel (5).

13) Conveyor (1 ) for vertical axis wind generator according to claim 1 1 or 12, wherein the longitudinal length of the first portion (50) is substantially equal to 2 times the longitudinal length of the third portion (52) and wherein the longitudinal length of the second portion (51 ) is substantially equal to 6 times the longitudinal length of the third portion (52).

14) Conveyor (1 ) for vertical axis wind generator according to any one of claims from 9 to 13, wherein the second portion (51 ) comprises a central portion having a maximum surface transversal extent substantially equal to 2 times the surface extent of the outlet opening (12) of the channel (5).

15) Vertical axis wind generator (30) comprising a rotor (3) and a conveyor (1 ) as defined in any one of claims from 1 to 14;

wherein said rotor (3) is contained in the chamber (2) of said con veyor (1 ); and

wherein said conveyor (1 ) is pivoted to said wind generator (30) such that the rotation of the conveyor (1 ) is independent from the rotation of the rotor (3).