EP3117097A1

EP3117097A1 - Transmission element, particularly for wind turbines

Info

Publication number: EP3117097A1
Application number: EP14708907.2A
Authority: EP
Inventors: Bruno GIACANI
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-03-11
Filing date: 2014-03-11
Publication date: 2017-01-18
Also published as: WO2015135573A1

Abstract

A transmission element (1), particularly for wind turbines, comprising a first shaft (2) and a second shaft (3) which are connected by way of a crossbar (4) provided with a first pair of arms (5) and a second pair of arms (6) that are perpendicular to each other. The second shaft (3) can move by rotation about a respective third axis (3a) and is connected rotatably to the first pair of arms (5) about a respective first axis (5a) that passes through the first pair of arms. The transmission element comprises a supporting element (7) that is associated with a supporting frame (8) and can move by rotation about a working axis (9a) that is normal to a respective working plane (9) that is inclined with respect to the third axis (3a). Furthermore, the supporting element (7) comprises seats (10) for the engagement of the second pair of arms (6) that are able to move by rotation about a respective second axis (6a) that passes through the second pair of arms. The first shaft (2) is integral with the crossbar (4) and is provided with a precession motion about a central axis (11) that is incident to the third axis (3 a) in the origin of the precession motion and performs a progressive rotation that is equal to a straight angle about a respective fourth axis (2a) that passes through the first shaft during the completion of the precession motion.

Description

TRANSMISSION ELEMENT, PARTICULARLY FOR WIND TURBINES

The present invention relates to a transmission element, particularly for wind turbines.

Wind power generators are increasingly widespread which, by way of the rotation of their vanes, make it possible to convert wind energy to electricity. Two types of wind power generators are principally known, which differ from each other in the different orientation of the rotation axis of their vanes. A first known type of wind power generator is the horizontal axis type in that it is provided with a propeller cuff from which branch at least two wind turbines in rotation about a horizontal axis, while a second known type is constituted by wind power generators with a vertical axis which are provided with a plurality of vanes that are arranged vertically on a circular supporting frame that rotates about a vertical axis. Such second type of wind power generator is sometimes preferred to the first for its economy of construction and for its ability to take energy from the wind in any direction, without requiring correction of the orientation of the generator whenever the wind direction changes. Such orientation operation is essential however for horizontal axis wind power generators, for which parallelism between the rotation axis of the vanes and the wind direction is a necessary element for their correct operation.

Such conventional vertical axis wind power generators are however not devoid of drawbacks among which is the fact that the vanes offer a high resistance to rotating against the wind, thus decreasing the overall efficiency of the generator. In particular, each vane, having a shape that is substantially sheet-like, is arranged radially with respect to the rotation axis. Such arrangement allows the vane to collect all the wind force when its surface is perpendicular to the wind direction. The pressure exerted by the wind force on its surface makes it possible to make the wind power generator rotate, for example clockwise, by making the vane move along a revolution circumference in the origin of which is the vertical rotation axis. In the several positions assumed along such revolution circumference, the vane can have an increasingly smaller surface that is normal to the wind direction on which to collect energy, until it is parallel thereto after a rotation of 90°. However, thanks to the presence of other vanes that are angularly spaced from the first, the generator continues to rotate. During the rotation of the generator, the first vane continues its movement along the revolution circumference through a further 90° angle, arriving at a position against the wind in which its surface is again struck by the wind, thus creating in this position an equal rotation force in the opposite direction, i.e. anticlockwise, with respect to the force described initially in the diametrically opposite position, thus bringing the generator to a standstill. Such drawback can be partially overcome by geometrically deforming the individual vanes, defining each vane by the concave/convex cross-section that can be conveniently oriented on the supporting frame so as to present the concave portion, which is adapted to collect the most energy possible, in a first position and the convex portion, which is adapted to deflect the wind outward in a second position that is against the wind (diametrically opposite to the previous position) thus offering the lowest possible resistance and ensuring the continuous rotation of the wind power generator.

Such solution only partially reduces such drawback, only slightly increasing the overall yield of the wind power generator.

In order to overcome this drawback, a wind power generator is known which is provided with vanes that can move about themselves, and it is described in patent application no. WO2007113401 in the name of Pierre Dieudonne. Such patent document discloses a wind power generator that is provided with a plurality of sheet-like vanes that are associated with a frame that rotates about a central axis. In addition to this a plurality of transmission elements for each vane are described, including linkages, pulleys and/or gearwheels, which constrain the orientation of the individual vanes as a function of their position on the supporting frame. In particular, each individual vane performs a rotation of 180° about a longitudinal central axis thereof during a complete rotation of 360° about the central axis, so as to present, in a first position, all of its surface perpendicular to the wind direction and offer the most resistance possible to the flow of air in order to collect the most energy with a decreasing yield until it reaches a second position, diametrically opposite to the previous position, in which the vane is presented edge-on to the wind direction, so as to offer no resistance and allow the continuous rotation of the generator. Such vane, in fact, collects energy from the wind increasingly as it returns to the initial point.

Such conventional wind power generator is also not devoid of drawbacks, including the fact that it requires the presence of a strong flow of air for electric current to be generated, given that reduced wind speeds impede the movement of the frame with which the vanes are associated in that they generate a resulting rotation force that is not sufficient to defeat the static friction of the several transmission elements that are connected to each other.

Another drawback of such conventional generators consists in that they require a high number of maintenance operations in order to ensure a continuous operation thereof over time. In fact, following intense use, the several transmission elements require frequent maintenance operations, such as for example the substitution of worn elements or the lubrication of mutually meshed elements.

The aim of the present invention consists in providing a transmission element, particularly for wind turbines, which eliminates the drawbacks and overcomes the limitations of the known art, by enabling the movement of a wind power generator even in the presence of low intensity winds.

Within this aim, an object of the present invention is to provide a transmission element that ensures practically continuous operation of a wind power generator, without requiring frequent shutdowns for maintenance operations.

Another object of the invention consists in providing a transmission element that is capable of offering the widest guarantees of reliability and safety in use.

Another object of the invention consists in providing a transmission element that is easy to implement and economically competitive when compared to the known art.

This aim and these and other objects which will become better apparent hereinafter are achieved by a transmission element, particularly for wind turbines, comprising a first shaft and a second shaft which are connected by way of a crossbar provided with a first pair of arms and a second pair of arms that are perpendicular to each other, said second shaft being able to move by rotation about a respective third axis and being connected rotatably to said first pair of arms about a respective first axis that passes through said first pair of arms, characterized in that it comprises a supporting element that is associated with a supporting frame and can move by rotation about a working axis that is normal to a respective working plane that is inclined with respect to said third axis, said supporting element comprising seats for the engagement of said second pair of arms that are able to move by rotation about a respective second axis that passes through said second pair of arms, said first shaft being integral with said crossbar and being provided with a precession motion about a central axis that is incident to said third axis in the origin of said precession motion and performing a progressive rotation that is equal to a straight angle about a respective fourth axis that passes through said first shaft during the completion of the precession motion.

Further characteristics and advantages of the invention will become better apparent from the detailed description of a preferred, but not exclusive, embodiment of a transmission element, particularly for wind turbines, which is illustrated for the purposes of non-limiting example with the assistance of the accompanying drawings wherein:

Figure 1 is a schematic perspective view of a transmission element, particularly for wind turbines, according to the invention;

Figures 2 and 3 are schematic partially sectional views, taken along a vertical plane, of the transmission element in Figure 1 in different operating configurations;

Figures 4, 6, 8, 10, 12, 14, 16 and 18 are schematic plan views of the transmission element in Figure 1 , with no means of support, in successive operating configurations;

Figures 5, 7, 9, 11, 13, 15, 17 and 19 are schematic partially sectional views of the transmission element shown respectively in Figures 4, 6, 8, 10, 12, 14, 16 and 18, taken respectively along the line V-V, VII- VII, IX-IX, XI- XI, XII-XII, XV-XV, XVII-XVII and XIX-XIX;

Figure 20 is a schematic side view of two transmission elements which are applied to a wind power generator, according to the invention.

With reference to the figures, the transmission element, particularly for wind turbines, generally designated by the reference numeral 1, comprises a first shaft 2 and a second shaft 3 which are connected by way of a crossbar 4 provided with a first pair of arms 5 and a second pair of arms 6 that are perpendicular to each other. The second shaft 3 extends along a respective third axis 3a about which it can move by rotation. The second shaft 3 is further connected rotatably to the first pair of arms 5 so as to move about a respective first axis 5a that passes through the first pair of arms.

According to the invention, the transmission element 1 comprises a supporting frame 8 with which a supporting element 7 is associated so that it can rotate. Such supporting element 7 is located on a working plane 9 that is inclined with respect to the third axis 3a and it is locked in translational motion with respect to the supporting frame 8, but it can move about a working axis 9a that is normal to the working plane proper. The supporting element 7 is further provided with seats 10 for the engagement of the second pair of arms 6 that are able to move about a respective second axis 6a that passes through the second pair of arms. The first shaft 2, which is extended along a respective fourth axis 2a, is integral with the crossbar 4 and is provided with a precession motion about a central axis 11 that is incident to the third axis 3 a in the origin of the precession motion. During the completion of the precession motion, i.e. during the rotation of a complete revolution about the central axis 11, the first shaft 2 performs a progressive rotation that is equal to a straight angle about the respective fourth axis 2a.

The supporting element 7 comprises a movable inner ring 13 that is associated rotatably with a fixed outer ring 12 that is integral with the supporting frame 8. Conveniently, the movable inner ring 13 can rotate about the working axis 9a and has on its own inner surface the engagement seats 10 in which the second pair of arms 6 is accommodated, leaving the first pair of arms 5 free. The working axis 9a and the third axis 3a are mutually angularly spaced by a working angle a. The axes 2a, 3a, 5a, 6a, 9a and 11 all converge on the point of origin of the precession motion.

The second pair of arms 5 is accommodated rotatably in respective slots 15a which are provided on a pair of tines 15 that define a fork 14 that is arranged at one end of the second shaft 3, thus enabling an articulated movement of the latter with respect to the crossbar 4. Unlike the second shaft 3, the first shaft 2 is integral with the crossbar 4 and is arranged perpendicular with respect to the first pair of arms 5 and to the second pair of arms 6.

The second shaft 3 is supported rotatably by adapted supporting means 16 that enable its rotation about the respective third axis 3a, while preventing its translational motion with respect to the supporting frame 8. The supporting means 16 comprise a fixed band 17 that is integral with the supporting frame 8 and by a movable band 18 that is integral with the second shaft 3, which, particularly, are rotatable with respect to each other by the interposition of rolling elements. In addition to this, the transmission element 1 comprises auxiliary- means 19 for the rotation of the first shaft 2 which, although they are not necessary in order to ensure the precession motion of the first shaft, enable a better stability in the distribution of the mechanical stresses to which the first arm 2 is subjected, while preventing such forces from being transmitted to the crossbar 4 or to the supporting element 7. The auxiliary means 19 comprise an outer ring 20 that accommodates internally a disk 21 that can rotate about the central axis 11. The disk 21 is provided with an accommodation seat 22 in which the first shaft 2 can move by rotation, but cannot slide axially. The accommodation seat 22 is slightly inclined with respect to the central axis 11 that passes through the disk 21 perpendicularly. Such inclination is equal to the nutation angle β that the fourth axis 2a has during the precession motion and such nutation angle β is equal to half of the working angle a.

The transmission element 1 thus described can support a vane 101 of a wind power generator 100 so that the vane can move along a revolution path 102 that is defined about the central axis 11 and can rotate about itself about a respective longitudinal central axis 103. The vane 101 further performs a progressive rotation that is equal to a straight angle about the central axis 103 during a complete revolution along the revolution path 102. Furthermore, the first shaft 2 is associated with at least one flap of the vane 101, while the second shaft 3 is associated, by way of a toothed wheel 23 or motion transmission elements, to means for generating electric power or the like.

In this specific embodiment, the angular distance between the working plane 9 and the central axis 11 and between the third axis 3 a and the central axis 11 is equal to the nutation angle β, as shown in Figures 2 and 3. Such nutation angle β is substantially comprised between 0° and 45°. The wind power generator 100 is provided with a substantially sheet-like vane 101 the two opposite flaps 101a and 101b of which are connected, by way of universal joints 104, to two separate transmission elements 1. The presence of the universal joints 104 enables the parallelism between the central axis 103 of the vane 101 and the central axis 11, as illustrated in Figure 20.

In other embodiments, not shown in the accompanying figures, the wind power generator 100 can comprise multiple wind turbines 101 that are arranged mutually side by side and are associated with the supporting frame 8 with corresponding transmission elements 1 or vanes 101 that are directly connected to the first shaft 2 without the interposition of the universal joint 104 so as to ensure parallelism, or in some cases the coincidence, between the central axis 103 and the fourth axis 2a.

Operation of the transmission element 1 is described hereinafter.

Initially the transmission element 1 is in the position shown in Figures 4 and 5 in which the first axis 5a is inclined by the nutation angle β with respect to a plane that is normal to the central axis 11 and the vane 101 has its surface perpendicular to the wind direction V. Furthermore, in such position, the third axis 3a and the second axis 2a are mutually coaxial, and are arranged on the same transverse plane which also contains the first axis 5a. The wind force V applied to the vane 101 tends to move the latter, which, coupled to the shaft 2 of the transmission element 1, starts to rotate anticlockwise (with respect to its own axis 103 as well), as shown in Figures 6 and 7, thus giving rise to the precession motion. Such rotation of the vane 101 along the revolution path 102 enables, through the movement of the first shaft 2, the movement of the crossbar 4. The movement of the crossbar 4 defmes a simultaneous angular movement of the two pairs of arms 5 and 6. In particular, the rotation of the second pair of arms 6 about the working axis 9a implies a corresponding rotation of the movable inner ring 13 that is engaged in the respective fixed outer ring 12. Such constraint enables the movement of the second pair of arms 6 exclusively on the working plane 9. The movement of the second pair of arms 6 also defmes the movement of the first pair of arms 5, in that the two pairs are coupled perpendicularly to each other. The first pair of arms 5 remains on the same inclined plane as the working angle a with respect to the working plane 9, given the presence of the fork 14, and rotates about the third axis 3a. The simultaneous rotation of 45° with respect to the central axis 11 of each pair of arms 5 and 6, as shown in Figures 8 and 9, enables a simultaneous inclination and rotation of the first shaft 2. Particularly, the first arm 2 rotates 45° about the respective fourth axis 2a, moving the vane 101 by the same angle, and rotates 90° about the central axis 11 along the revolution path 102, thus defining a quarter turn of the precession motion. The absence of mechanical kinetic movement mechanisms with a high static friction coefficient, such as for example mutually meshing sprockets, enables the movement of the wind power generator 100 even in the presence of low intensity winds.

The vane 101 now presents a surface that is inclined by 45° with respect to the wind direction V so as to continue to collect energy for its rotation. The movement of the vane 101 continues, as shown schematically in Figures 10 and 11 , until the position shown in Figures 12 and 13 in which each pair of arms 5 and 6 is angularly rotated by 90° from the position shown in Figures 4 and 5, and the third axis 3 a and the fourth axis 2a are mutually incident in the origin of the precession motion, and are also co- planar with the second axis 6a. Each pair of arms 5 and 6 has performed a further rotation of 45°, moving the first shaft 2 a further 90°. In this position the first shaft 2 is coincident with the working axis 9a and is angularly distanced 180° from the initial position, having performed a rotation of 90° about the respective fourth axis 2a, bringing the vane 101 to be substantially parallel to the wind direction V. In this position the vane 101 offers no resistance to the wind force and, consequently, owing to inertia, it continues its rotation, i.e. its precession motion about the central axis 11.

By continuing the rotation, as shown in Figures 14 and 15, the vane 101 starts to be inclined with respect to the wind direction, as shown in Figures 16 and 17, thus offering a portion of surface that is normal to the wind, which will collect energy from the wind, with an increasing yield, for its rotation. Thanks to the mechanical couplings of the crossbar 4, the vane 101 continues its rotation, as shown in Figures 18 and 19, and, rotated 180° with respect to its own axis 103, is brought back to the initial position in which all of its surface is perpendicular to the wind direction V. Obviously, the vane 101 , during the rotation just described, transmits its motion deriving from the wind force to the second shaft 3 which, connected to an electricity generator by way of the toothed wheel 23, produces electricity.

In other embodiments, which are not shown in the present application, there can be means of orientation of the wind power generator 100 interposed between the supporting frame 8 and the installation surface of the wind power generator. Such means of orientation can be functionally connected to special sensors that are adapted to detect the wind direction and as a consequence orient the supporting frame 8 to take optimum advantage of the wind energy.

In practice it has been found that the transmission element, particularly for wind turbines, according to the present invention, achieves the intended aim and objects in that it makes it possible to move a wind power generator even in the presence of low intensity winds. In fact, the transmission element, which is provided with pivoted elements in adapted engagement seats only, has a low static friction coefficient with respect to the friction coefficients of mechanical elements of conventional solutions, making it possible to generate energy even in the presence of low intensity winds.

Another advantage of the transmission element, according to the invention, consists in ensuring a continuous operation over time, without requiring frequent maintenance operations, since the elements that make up the transmission element are not subject to rapid deterioration owing to fatigue wear, as for example occurs for the mechanical elements of conventional solutions.

Another advantage of the transmission element, according to the invention, consists in providing a wind power generator that is particularly low cost when compared to the known art. Such reduction of costs is evident given the low number of simple components that make up the wind power generator disclosed here with respect to conventional wind power generators.

The transmission element can be used in different mechanical fields, and is not limited to the wind power sector described herein.

The transmission element, particularly for wind turbines, thus conceived is susceptible of numerous modifications and variations all of which are within the scope of the appended claims.

Moreover, all the details may be substituted by other, technically equivalent elements.

In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A transmission element (1), particularly for wind turbines, comprising a first shaft (2) and a second shaft (3) which are connected by way of a crossbar (4) provided with a first pair of arms (5) and a second pair of arms (6) that are perpendicular to each other, said second shaft (3) being able to move by rotation about a respective third axis (3 a) and being connected rotatably to said first pair of arms (5) about a respective first axis (5a) that passes through said first pair of arms, characterized in that it comprises a supporting element (7) that is associated with a supporting frame (8) and can move by rotation about a working axis (9a) that is normal to a respective working plane (9) that is inclined with respect to said third axis (3 a), said supporting element (7) comprising seats (10) for the engagement of said second pair of arms (6) that are able to move by rotation about a respective second axis (6a) that passes through said second pair of arms, said first shaft (2) being integral with said crossbar (4) and being provided with a precession motion about a central axis (11) that is incident to said third axis (3a) in the origin of said precession motion and performing a progressive rotation that is equal to a straight angle about a respective fourth axis (2a) that passes through said first shaft during the completion of the precession motion.

2. The transmission element (1) according to claim 1, characterized in that said supporting element (7) comprises a movable inner ring (13) that is associated rotatably with a fixed outer ring (12) that is integral with said supporting frame (8), said movable inner ring (13) being able to rotate about said working axis (9a) and having said engagement seats (10) on its own inner surface.

3. The transmission element (1) according to claims 1 and 2, characterized in that said first shaft (2) is perpendicular to said pairs of arms (5, 6).

4. The transmission element (1) according to one or more of the preceding claims, characterized in that said second shaft (3) has, at one of its ends, a connecting fork (14), said fork (14) having a pair of respective tines (15) provided with slots (15a) in which the first pair of said arms (5) is accommodated rotatably.

5. The transmission element (1) according to one or more of the preceding claims, characterized in that it comprises means (16) for supporting said second shaft (3) which are composed of a fixed band (17) that is integral with said supporting frame (8) and a movable band (18) that is integral with said second shaft (3), said movable band (18) being able to rotate with respect to said fixed band (17) by the interposition of rolling elements.

6. The transmission element (1) according to one or more of the preceding claims, characterized in that it comprises auxiliary means (19) for the rotation of said first shaft (2), which are composed of an outer ring (20) that accommodates internally a disk (21) that can rotate about said central axis (11), said disk (21) being provided with an accommodation seat (22) in which said first shaft (2) can move by rotation.

7. The transmission element (1) according to one or more of the preceding claims, characterized in that said working axis (9a) and said third axis (3a) are mutually angularly spaced by a working angle (a).

8. The transmission element (1) according to one or more of the preceding claims, characterized in that said working angle (a) has a value that is twice a nutation angle (β) of said fourth axis (2a) during the precession motion about said central axis (11).

9. A wind power generator (100) of the type comprising at least one vane (101) that can move along a revolution path (102) that is defined about a central axis (11) and can rotate about itself about a respective longitudinal central axis (103), said at least one vane (101) performing a progressive rotation that is equal to a straight angle about said central axis (103) during a complete revolution along said revolution path (102), characterized in that said at least one vane (101) is associated with a supporting frame (8) by way of a transmission element (1) according to one or more of the preceding claims.

10. The wind power generator (100) according to claim 9, characterized in that said first shaft (2) is associated with at least one flap of said at least one vane (101) and said second shaft (3) is associated with means for generating electric power or the like.