[0001] . The present invention regards a device for generating electric energy from renewable sources and in particular a wind electric generator. [0002] . Generation of electric energy from renewable sources has become a more and more felt need worldwide over the last years. The risk that, in a not very far future, the extraction of petroleum may stop or slow down due to the exhaustion of the oil deposits, or also due to other political or economical reasons, has given a push to the search for new sources of energy. In addition, reasons of ecological nature have concentrated many efforts on the development of low environmental impact systems, especially those systems not involving the discharge of harmful substances into the air or water. Among these systems, the solar power generators, the utilization of geothermal energy, and the wind electric generators can be mentioned. [0003] . Wind energy is already broadly exploited in the USA, Europe, and in other industrialized countries, above all in those countries that are exposed to considerable ventilation. The need to spread its use potentially to the whole territory, and to each weather condition, has provided the drive for the development of highly efficient devices, that is, such to advantageously operate also in the presence of a low ventilation.

[0004] . The wind electric generators are generally composed of a tower which is even more than 100 meters high, so as to better intercept the wind, at the top part of which the electric generator is located. The electric generator is composed of an alternator and a motor reducer, whose shaft is rotated, through suitable gears, by a large-sized blade which intercepts the wind energy.

[0005] . However, the known wind plants have several drawbacks, which limit the diffusion thereof. First of all, the difficulties regarding the installation, requiring the transport and positioning of the large- sized and heavy elements constituting the plant, make the installation at the highest, thus hardly accessible, points substantially impracticable. Anyway, the installation and maintenance cost is extremely' high, since it is necessary to use large- sized fixtures, particularly cranes.

[0006] . Second, the visual impact of the known plants is such to discourage the installation within protected landscape environments. In fact, it is impossible to camouflage the above-described plants in a natural environment. [0007] . Another problem related to the known wind generators is the functioning efficiency. While in some cases the ventilation is so weak, or even absent, to make the plant productivity to collapse, in case of strong ventilation, instead, an energy overproduction can be obtained, leading to storage and distribution, as well as structural and mechanical safety problems. In substance, therefore, the wind energy plants are affected by a functioning unevenness problem. [0008]. Therefore, the object of the present invention is to provide a wind electric generator which addresses one or more of the problems set forth above .

[0009] . Such object is achieved by a wind electric generator as outlined in the annexed claims, the definitions of which form an integral part of the present description.

[0010] . Further characteristics and advantages of the present invention will be more clearly understood from the following description of an embodiment, given by way of non-limitative example only, wherein:

- Figure 1 represents a sectional side view of a wind electric generator according to the invention;

- Figure 2 represents a top schematic view of the turbine of the wind electric generator of figure 1; - Figure 3 represents a sectional side view of a detail of the wind electric generator of figure 1;

- Figure 4 represents a schematic view of a detail of the wind electric generator of figure 1;

- Figure 5 represents a sectional side view of a detail of a different embodiment of the wind electric generator according to the invention;

- Figure 6 represents a schematic front view of an embodiment of the wind electric generator according to the invention;

- Figure 7 represents a sectional schematic view of a further embodiment of the wind electric generator according to the invention.

[0011] . With reference to the figures, the wind electric generator of the invention, generally indicated with the number 1, comprises a tower 2, at the top part of which wind collection means 3 are arranged.

[0012] . The tower 2 may be tubular-shaped, as shown in the drawing, or pylon-shaped, substantially similar to a crane. In the latter case, the whole structure will have a lesser weight and a more aerial visual impact, without for this renouncing to robustness and stability.

[0013] . The tower 2 may be made of cement, steel, or other metal alloys, and it may be painted in a colour matching the surrounding environment.

[0014] . The tower 2 is hollow, in such a manner to allow passing - therein - the required services (lift, electrical system, etc) , wiring and cables for the generated electric energy.

[0015] . The wind collection means 3 arranged at the top part of the tower 2 consist of a case 6 in which a vertical axis turbine 7 is housed.

[0016] . The turbine 7 comprises a stator 8 and a rotor 9. The stator 8 constituting the side walls of the case 6, comprises a plurality of orientable vanes 10, so as to better exploit the wind impact force on the rotor 9. As shown by way of example for a single vane 10 in figure 2, the orientation of all the vanes 10 may be implemented thanks to a rotation thereof, shown by the arrows, around a vertical axis 11 which is pivoted on the structure of the case 6. [0017] . In an embodiment, the side surface of the case 6, externally with respect to the vanes 10, comprises a loose mesh netting (not shown) , used as a bird control netting.

[0018] . The case 6 superiorly comprises an opening 30, acting as a vent outlet for the air intercepted by the turbine 7. [0019] . In an embodiment, the circular crown 31 constituting the roof of the case 6 comprises solar panels for the production of further electric energy, which may be used, for example, for the operation of all the service uses of the wind power station

(lighting, drive and control units, electric actuators, solenoid valves, etc.).

[0020] . The rotor 9 is mounted idle at the top of the tower 2 and comprises a plurality of blades 12. The blades 12, in the embodiment shown in figure 2, have a concave profile, so as to better intercept the thrust generated by the wind oncoming through the stator 8.

[0021] . In an embodiment, the blades 12 are made of a light material, such as aluminium alloy or wood coated with glass fibre or carbon fibre, or they are entirely made of carbon fibre, so as to confer the required strength and elasticity thereto. [0022] . The total area of the blades 12 of the rotor 9, that is the total area of wind impact, may range between 500 sqm and 2500 sqm, or between 1000 and 2000 sqm, depending on the power intended to be installed. [0023] . The wind collection means 3 are operatively connected, through a wind energy transmission and transformation system, to electric energy generator means 22.

[0024] . In an embodiment of the invention shown in the figures, the wind energy transmission and transformation system comprises motion transmission and transformation means 14, which are operatively connected to said wind collection means 3 and which transmit the motion from the turbine 7 to a plurality of hydraulic pumping means 15.

[0025] . In the example shown in the figures, such motion transmission and transformation means 14 comprise a gear wheel 13, mounted integral to the rotor of the shaft 9, along whose periphery they mesh driven gear wheels 16. Possibly used in other embodiments may be different motion transmission and transformation systems, selected from among the conventional ones known to those skilled in the art. [0026] . Each of the driven gear wheels 16 is integral to a shaft 17 which, in turn, transfers motion to the rotor of respective hydraulic pumping means 15. The hydraulic pumping means 15 will typically be two or more; for example, eight hydraulic pumping means 15 will be arranged at regular intervals around the gear wheel 13.

[0027] . ^' The hydraulic pumping means 15 are typically high pressure hydraulic pumps. [0028] . Each hydraulic pumping means 15 is operatively connected to a closed hydraulic circuit which comprises a delivery pipe 18 and a return pipe 19. Such pipes 18, 19 are flexible or rigid and have a length at least corresponding to the maximum height of the tower 2.

[0029] . The closed hydraulic circuit further comprises motorization hydraulic means 20, to which the pipes 18, 19 may be operatively connected. The motorization hydraulic means 20, which may typically be a hydraulic motor or a hydraulic motor reducer, are associated to respective electric energy generator means 22, typically alternators, through transmission means 21. Typically, such transmission means 21 will be implemented by means of a driving shaft. In this manner, the high pressure fluid pumped by the hydraulic pumping means 15 actuates the motorization hydraulic means 20 which, in turn, convert the kinetic energy into electric energy for the production of alternate current by means of the alternator 22. [0030] . As shown in the figures, the motorization hydraulic, means 20 and the corresponding electric energy generator means 22 are arranged at the base of the tower 2. [0031] . As stated before, electric energy generator means 22 correspond to each hydraulic pumping means 15. Said means 22 are connected to an electric energy transformation and distribution system of the conventional type (not shown) , which will comprise potential booster converters, a network of power lines and transformers adapted to reduce the voltage according to the needs of the various users. [0032] . In an embodiment of the invention, the motion transmission and transformation means 14, or the motorization hydraulic means 20, comprise transmission engaging/disengaging means (not shown) . Such means will be controlled or they will be automatic, and may comprise, for example, engaging/disengaging mechanic means provided with coupling systems such as, for example, two discs couplable • by means of an axial gear, or a clutch. If said mechanical transmission engaging/disengaging ^' means are a clutch, they will be preferably a dry clutch, an oil-immersed clutch or a centrifugal clutch.

[0033] . In another embodiment, in place of such transmission engaging/disengaging means, the hydraulic pumping means 15 comprise a secondary by-pass hydraulic circuit and by-pass valve means, suitable to recirculate the fluid within said secondary hydraulic circuit, thus excluding the above-described closed hydraulic circuit comprising said pipes 18, 19. Such by-pass valve means typically comprise a three-way solenoid valve, of the type suitable for high pressures (about 200 bars) . Therefore, in this embodiment, when the secondary by-pass circuit is selected, the rotor of the hydraulic pumping means 15 will always be operative, but it will run idle and not send the pressurized fluid to the motorization hydraulic means 20 through the delivery pipe 18. [0034] . In this manner, either by operating on said transmission engaging/disengaging means, or having one or more hydraulic pumping means 15 to run idle, it is possible to exclude one or more electric energy generator means 22 from production when the number of rotations of the turbine 7 is below predefined threshold values. This need may arise when the wind blows at a low speed. Vice versa, as the wind speed and, therefore, the available wind energy increases, a number of electric energy generator means 22 may be progressively put to production, exploiting at the best the potentiality of the plant. However, if the wind exceeds a given threshold value - which may vary according to the power of the installed wind plant - such as, for example, during a gale, the above- described procedure may be reversed, progressively excluding one or more electric energy generator means 22 from production, so as to avoid an overproduction, which is difficult to be used.

[0035] . In a further embodiment, it is possible to reduce the wind impact on the blades 12 of the turbine 7, and therefore the rotation speed of the same, by reducing the gap between the vanes 10 of the stator 8, by rotation of the vanes 10 around their vertical axis 11. Therefore, in this manner it is possible to avoid an overproduction of electric energy without having to exclude one or more electric energy generator means 22 as described above, or by synergically operating with said procedure of exclusion of the means 22. [0036] . In an embodiment shown in figure 4, the wind electric generator of the invention comprises an automatic system 23 for distributing power to the various electric energy generator means 22. [0037] . Such automatic system 23 comprises means 24 for measuring the velocity and optionally the direction- of the wind, typically an anemometer or an electronic sensor, connected with a drive and control unit 25 which is in turn operatively connected, through suitable wiring 26, to electric actuators connected to each of the mechanical transmission engaging/disengaging means - associated to the motion transmission and transformation means 14 or to the motorization hydraulic means 20 - or, alternatively, to said by-pass valve means of the hydraulic pumping means 15. Furthermore, said drive and control unit 25 will be operatively connected to electric actuators (not shown) of the orientable vanes 10 of the stator 8, in such a manner to drive the opening/closure, hence the orientation thereof.

[0038] . The drive and control unit 25 serves the following ^• functions : reading the velocity of the wind; assigning to each of said transmission engaging/disengaging means a first threshold value of the velocity of the wind, different for each transmission engaging/disengaging means, in such a manner to create a first set of preset incremental threshold values; comparing the read velocity value with said first set of preset incremental threshold values; - sending an on-off control signal to each of said transmission engaging/disengaging means, wherein said "on" control corresponds to the engaging of the transmission, and wherein each of said control signals is an "off" control if the read value of the velocity of the wind is lower than the corresponding threshold value, while it is an "on" control if the read value of the velocity of the wind is higher than the corresponding threshold value.

[0039] . Thus, it is possible to exploit at the best the wind energy, increasing the electric energy production as the wind energy becomes available. [0040] . Alternatively, the drive and control unit 25 may be used for: reading the velocity of the wind; assigning to each of said by-pass valve means a first threshold value of the velocity of the wind, different for each by-pass valve means, in such a manner to create a first set of preset incremental threshold values; comparing the read velocity value with said first set of preset incremental threshold values; sending an on-off control signal to each of said by-pass valve means, wherein said "on" control corresponds to delivery of the fluid through the respective delivery pipe 18 and said "off" control corresponds to interruption of said delivery, and wherein each of said control signals is an "off" control if the read value of the velocity of the wind is lower than the corresponding threshold value, while it is an "on" control if the read value of the velocity of the wind is higher than the corresponding threshold value.

[0041] . Furthermore, the drive and control unit 25 may be used for:

- Reading the velocity of the wind;

- assigning to each of said transmission engaging/disengaging means or of said by-pass valve means a second threshold value of the velocity of the wind, different for each transmission engaging/disengaging means or for each by-pass valve means, in such a manner to create a second set of preset incremental threshold values, wherein the lowest threshold value of said second set is higher than the highest threshold value of said first set and it is higher than or equal to a preset value of the velocity of the wind;

- comparing the read velocity ' value with said second set of preset incremental threshold values;

- sending an on-off control signal to each of said transmission engaging/disengaging means or to each of said by-pass valve means, wherein said "on" control corresponds to the engaging of the transmission or delivery of the fluid through the respective delivery pipe 18, respectively, and said "off" control corresponds to the interruption of said delivery, and wherein each of said control signals is an "on" control if the read value of the velocity of the wind is lower than the corresponding threshold value of said second set, while it is an "off" control if the read value of the velocity of the wind is higher than the _. corresponding threshold value of said second set. 42] . In an embodiment, the drive and control unit serves the following further functions:

- Reading the velocity and optionally the direction of the wind;

- Comparing the read velocity with a preset threshold value;

- Sending a control signal to the actuator of the orientable vanes 10 of said stator 8 in such a manner to direct said vanes 10 as a function of said read direction of the wind and/or as a function of said read velocity of the wind, wherein the gap between said vanes 10 is reduced if said read velocity of the wind is higher than said preset threshold value. [0043] . Therefore, as described above, the wind electric generator of the invention may best exploit the potentialities thereof according to the velocity of the wind: in fact, up to a given speed, the energy production will be progressively increased as a function of the increasing available wind energy; whereas, if the wind speed rises beyond a given preset threshold, one or more electric energy generator means 22 may be automatically disengaged, thus avoiding an overproduction of electric energy.

[0044] . The wind electric generator of the invention may be completed by a system for access to the top part of the tower 2 and a platform extending around the case 6 of the turbine 7. This platform may be used both to facilitate the maintenance of the turbine 7 and the hydraulic pumping means 15, and as a sighting post, for example, for the civil defence or the forest ranger. To this aim, remote smoke detectors may be installed on the platform, for monitoring possible wildfires. Such smoke detectors will be generally connected to a remote alarm system.

[0045] . • In a different embodiment shown in figure 5, the vertical axis turbine is replaced by a traditional propeller 40. The propeller 40 is associated to a shaft 41 which ends at the opposite end with a conical gear wheel 42 which, in cooperation with a second conical gear wheel 43, transforms the rotation around a horizontal axis into a rotation around a vertical axis. The second conical gear wheel 43 is connected to a respective shaft 44 which also supports the driving gear wheel 13.

[0046] . In this embodiment, the motion transmission and transformation means 14 are entirely analogous to those described for the first embodiment and thus they shall not be described more in detail herein. [0047] . In a further embodiment, shown in figure 6, the tower 2 supports a bearing structure 106, which comprises a framework shaped to form an isosceles triangle or another polygonal structure, arranged at whose vertexes are wind collection means which comprise propellers 140 of conventional type, connected to motion transmission and transformation means (not shown) contained in respective cases 6. Such motion transmission and transformation means are entirely analogous to those described above regarding the embodiment of figure 5 and thus shall not be described more in detail herein. Each of such motion transmission and transformation means may be operatively connected with one or more electric energy generator means 22 arranged at the base of the tower 2 .

[0048] . In this embodiment, the difference with respect to the version of figure 5 is that, instead of having only one large propeller, provided for were three small propellers. This increases the structural stability and resistance of the assembly and allows operating even in case of extremely strong wind, conditions under which a normal wind energy plant provided with a single propeller would not operate due to the risk of structural collapse. This leads to obtaining higher production of electric energy. [0049] . In a further embodiment, shown in figure 7, the vertical axis turbine is coupled to a propeller- equipped generation unit 50.

[0050] . The unit 50 is arranged at the top part of the case 6, in such a manner to project outside the diameter of said case 6 to avoid interference with the propeller 40.

[0051] . The propeller-equipped generation unit 50 comprises a case 51 which supports the propeller 40 and encloses the motion transmission and transformation means (114).

[0052] . The propeller 40 is associated to a shaft 41 which ends at the opposite end with a conical gear wheel 42 which, in cooperation with a second conical gear wheel 43, transforms the rotation around a horizontal axis into a rotation around a vertical axis. The second conical gear wheel 43 is connected to a respective shaft 44 which also supports the driving gear wheel 130.

[0053] . Preferably the propeller 40 has a diameter of 40-60 metres.

[0054] . Also arranged on the roof of the case 6 in this case shall be one or more openings 300 for venting the air intercepted by the turbine 7. [0055] . In this embodiment, the motion transmission and transformation means 114 are entirely analogous to those described regarding the first embodiment and thus comprise hydraulic pumping means 15 operatively connected to a closed hydraulic circuit which comprises a delivery pipe 18' and a return pipe 19' . [0056]. The path of such pipes 18', 19' to and from the hydraulic motorisation means 20 arranged at the base of the tower 2 is intercepted by three-way valve means 52, which also intercept the pipes 18, 19 coming from the motion transmission and transformation means 14 associated to the turbine 7.

[0057] . The valve means 52 are operatively connected to a delivery pipe 118 and a return pipe 119 which ends in said hydraulic motorisation means 20. The valve means 52 allow selecting between the hydraulic circuit associated to the turbine 7 and that associated to the propeller 40, hence the production of electric energy may occur both due to the rotation of the blades 12 of the turbine 7 and the propeller 40.

[0058] . This allows maximum exploitation of the force of the wind, especially in cases where the propeller 40 has a small diameter (40-60 metres) while the turbine 7 is large in size. As a matter of fact, in such case, with low wind velocity, the propeller 40 - which has a lower inertial mass - shall operate while if the wind increases considerably the propeller 40 shall be blocked - to allow the operation of the turbine 7 which develops a considerably higher power. This operating mode allows maximum reduction of the inoperative times of the plant.

[0059] . Thus, in an embodiment the drive and control unit 25 serves the following functions:

- Reading the velocity of the wind;

- Assigning to said three-way valve means 52 a preset threshold value of the velocity of the wind;

- sending to said valve means 52 an "on-off" control, wherein the "on" control corresponds to the selection of the hydraulic circuit associated to said propeller 40 and the "off" control corresponds to the selection of the hydraulic circuit associated to said turbine 7 and to a command for blocking the rotation of said propeller 40, and wherein said "on" control is sent for velocities of the wind lower than said threshold value and said "off" control is sent for velocities of the wind higher than said threshold value.

[0060] . In a further embodiment of the invention, not shown in the figures, associated to said turbine 7 is an electric motor. For example, such electric motor may intervene, through suitable gears, on said driving gear wheel 13. Such electric motor is actuatable through the electric energy generated by the photovoltaic cells arranged on the circular crown 31 of the roof of the case 6 and it serves to overcome the inertia of the turbine 7 at low velocities of the wind, hence allowing the wind electric generator of the invention to operate even under low wind conditions .

[0061] . The advantages of the invention are clear from the description above. [0062] . Using a vertical axis turbine, instead of traditional horizontal axis propellers, drastically reduces the visual impact of the plant. [0063] . Having provided for alternators 22 at the base of the tower 2 instead of at the top - as in the case of traditional plants - allows reducing the weight of the part of the plant arranged at the top of the tower 2, this essentially leading to reducing the high installation costs. Furthermore, the presence of these apparatuses at the base reduces times and costs related to repairs and maintenance.

[0064] . Providing for a plurality of hydraulic pumping means 15 disengageable or engageable depending on the velocity of the wind allows modulating the operative capacity of the plant as a function of the meteorological conditions, in order to maintain its productivity as constant as possible, such problem being typical of traditional plants. Furthermore, risks related to complete stalling of the plant due to a failure are substantially reduced, in that at least one alternator 22 is always operative. [0065] . Obviously, the invention may be subjected - by a man skilled in the art - to numerous variants without departing from the scope of protection defined by the claims attached herein. [0066] . For example, the turbine 7 may have a different structure with respect to that shown in the figures. For example, used may be a Savonius -wind turbine or any other known type of wind turbine capable of exploiting the impact of the wind to the maximum.

[0067] . Furthermore, transmission of energy from the turbine to the alternator through a closed hydraulic circuit may be replaced by a conventional mechanical transmission.