Patent Description:
The invention also relates to a solar tracker system provided with such a reduction gearbox and a process for installing such a system.

Systems for producing electricity comprising one or more solar trackers are currently known.

Each solar tracker of the so-called single-axis type is provided with a plurality of photovoltaic panels mounted in a row on one or more orienting crossbars that extend substantially parallel to the ground.

These orienting crossbars may be simple metal profiles or other bars -for example, hollow- or metal beams, up to several tens of metres long, and may be rotated on themselves in order to vary the inclination of the photovoltaic panels relative to the sun and maximise the amount of solar radiation they capture and transform into electricity.

Photovoltaic panels generally have a rectangular shape.

Panels are preferably mounted in a row on the respective crossbar with their long side perpendicular to the crossbar itself, i.e. in the so-called "vertical" or "portrait" mounting mode; in some types of trackers, called "<NUM>-vertical" or "<NUM>-portrait", only one row of panels is mounted on each crossbar; in other types of machines, called "<NUM>-vertical" or "<NUM>-portrait" trackers, two rows of panels are installed.

In still other types of systems, currently called "horizontal" or "landscape", one or more rows of panels are mounted on the crossbar with the long side parallel to the crossbar.

In some solutions, two or more parallel rows of solar trackers are transversally connected by a transmission, so that both rows are driven by a same motor.

Solar trackers are more cost-effective when they support a relatively large number of photovoltaic panels; consequently they have considerable lengths, exceeding, in some cases, <NUM> m.

Each large size tracker currently comprises a plurality of vertical uprights <NUM> -often made as posts-fitted into the ground at appropriate distances from each other and supporting the orienting crossbars at several points along their span (<FIG>).

Each orienting crossbar is mounted on the uprights by means of rotating bearings that allow the crossbar to rotate on itself.

In some embodiments, each orienting crossbar is driven by a reduction gearbox fixed to one or both ends of the crossbar.

Known examples of this type of reduction gearbox are shown for example in <FIG>, <FIG> of the utility model <CIT>and in <FIG> of the utility model <CIT>.

Currently, the orienting crossbars are mounted with an inclination relative to the ground no greater than <NUM>%, corresponding to approximately <NUM>° sexagesimal.

In the current solar trackers, the orienting crossbars placed on opposite sides of the reduction gearboxes are in fact coaxial, as the reduction gearbox has a cylindrical coupling that does not provide for any adjustment.

Such trackers therefore hardly adapt to non-flat grounds, unless corrective actions are taken that are all the more relevant the longer the tracker is.

This drawback is emphasized by the scarcity of available land for large-scale photovoltaic installations at least in Italy, by the current competition between photovoltaic energy production and agriculture: although techniques for combining agricultural and photovoltaic energy production on the same ground have long been known, they are currently not yet widespread.

<FIG> actually show the solutions predominantly used today to install large size solar trackers on uneven ground.

According to a first solution currently practised, the solar tracker <NUM> of <FIG> comprises a plurality of solar panels, not shown, fixed to a single orienting crossbar <NUM>, which is kept substantially straight and parallel to the mean line of the ground T, slightly inclined and undulating, by varying the length of the part of the posts -i.e. uprights- <NUM> protruding out of the ground.

The orienting crossbar <NUM> is fixed to and rests on the top of the posts <NUM> by means of bearings <NUM>.

This solution is only effective with relatively small undulations and irregularities in the ground profile below a same tracker, in relation to the average slope line of the ground itself, up to <NUM>-<NUM> metres; noticeable irregularities require some posts to be lengthened considerably and their cross-section increased and strengthened so that they can withstand a bending moment at the base of the post that increases proportionally to the difference in height.

In the case of significant elevation changes in the ground beneath the structure, this first solution soon becomes expensive and complicated to manage.

In a second solution currently practised, the ground surface T is made more even and flat by means of so-called cut/fill earth-moving works with which the ground is removed in some areas and taken into other areas (<FIG>); this solution is always technically feasible but very expensive and takes longer to implement.

In a third solution currently practised, solar trackers are made shorter so that they can better follow the pre-existing profile of the ground, reducing civil engineering works and related costs.

However, shorter trackers have higher specific costs.

In order to limit the latter, some known systems share a single electronics or handling system between several short trackers.

In a fourth solution currently practised, the solar trackers <NUM>" comprise several orienting crossbars <NUM>A, <NUM>B that are not coaxial with each other, which overall make up a broken line (<FIG>).

In this solution, a bearing is mounted on each post <NUM>, which allows the connection of two orienting crossbars <NUM>A, <NUM>B inclined to each other, thus better adapting the solar tracker to the existing ground, reducing the cut/fill costs.

However, since at each change of slope it is necessary to leave a space between two adjacent photovoltaic panels larger than the axial footprint of the bearing located at that point, i.e. at each coupling point of the orienting crossbars 5A, 5B, the tracker is significantly longer for the same number of panels installed thereon, thus increasing the gross surface area occupied.

For the same installed electrical power, this solution therefore requires a larger plot of land, increasing the investment costs of the system.

It is also clear that installation costs according to the latter solution also increase very quickly as the unevenness of the ground increases.

The German Utility model <CIT> discloses a supporting device for rotatably mounting a plurality of solar modules; this supporting device comprises a transmission <NUM>, an input shaft <NUM> and two rotary joints <NUM>; the input shaft <NUM> is configured for driving the transmission <NUM> and the two rotary joints <NUM> are configured for driving and rotating two inclination shafts <NUM> even when said shafts <NUM> are not coaxial one to another.

This known supporting device allows setting photovoltaic plants also on uneven grounds or floors.

An object of the present invention is to obviate the above-mentioned drawbacks of the prior art and in particular to provide even large size solar trackers that can also be conveniently installed on uneven and/or undulating ground, with lower costs for earth-moving works or for compensating for unevenness of the ground by varying the above-ground length of the posts <NUM>, or with lower costs than trackers with shorter structures, while reducing the unused surface area because occupied by spaces between the photovoltaic panels.

Such object is achieved, according to the present invention, by a reduction gearbox having the features according to claim <NUM>.

According to a particular embodiment of the invention, the reduction comprises at least two take-off joints (<NUM>, <NUM>', <NUM>").

In a second aspect of the invention, this object is achieved by a system for producing electricity having the features according to claim <NUM>.

In a third aspect of the invention, this object is achieved by a process for installing a system for producing electricity having the features according to claim <NUM>.

Further features of the invention are the subject matter of the dependent claims.

The advantages attainable with the present invention shall become more readily apparent, to the person skilled in the art, by the following detailed description of a particular, non-limiting example of embodiment, illustrated with reference to the following schematic figures.

<FIG> relate to a reduction gearbox and an associated solar tracker according to different particular embodiments of the present invention.

The reduction gearbox of the embodiment in <FIG>, <FIG> is globally referred to as <NUM>III.

The reduction gearbox of the embodiment in <FIG>, <FIG> is globally referred to as <NUM>IV.

The reduction gearbox of the embodiment in <FIG>, <FIG> is globally referred to as <NUM>V.

The reduction gearbox of the embodiment in <FIG>, <FIG>, <FIG> is globally referred to as <NUM>'.

The reduction gearbox of the embodiment in <FIG>, <FIG>, <FIG> is globally referred to as <NUM>".

The reduction gearbox of the embodiment in <FIG>, <FIG>, <FIG> is globally referred to as <NUM>.

According to an aspect of the invention, the reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V comprises a housing <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, a toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, a power input <NUM>, at least two power take-offs <NUM>, <NUM>', <NUM>',<NUM>III, <NUM>IV, <NUM>V at least one take-off joint <NUM>, <NUM>', <NUM>" (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

The toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V may have a substantially and overall tubular shape, and preferably forms a through cavity <NUM> (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>,).

The toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V forms a toothing, such as an arc of toothing <NUM> (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

The housing <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V may comprise a casing -for example of a substantially tubular (<FIG>, <FIG>, <FIG>) or annular shape- extending around and/or containing at least part of the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V and/or at least part of the two power take-offs <NUM>, <NUM>', <NUM>" (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

The housing <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V may form one or more fixing feet <NUM> or other fixing brackets by means of which the housing can be fixed e.g. at the top of an upright or post <NUM> or other support.

The power input <NUM> is configured for driving the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V and may comprise, for example, a drive shaft on which a screw of a worm screw is preferably cut, or a pinion, spool or other toothed wheel, preferably with external toothing, or even a part of a clutch.

The power input <NUM> and the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V together form a speed reduction sub-assembly that reduces the rotation speed of the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V relative to the rotation speed of the shaft or other element belonging to the power input <NUM>.

The ratio between the rotation speed of the shaft or other element belonging to the power input <NUM> and the rotation speed of the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V is preferably between <NUM>-<NUM> times, or between <NUM> and <NUM> times, as for example in the case of applications with only one reduction step, or between <NUM> and <NUM> as for example in the case of applications with two reduction steps, in particular with two worm screw cascade systems.

The toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V is configured for driving both power take-offs <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V by rotating on itself around a crown rotation axis ARC.

Each power take-off <NUM>, <NUM>', <NUM>" comprises a rotating interface configured for rotating on itself about a respective take-off rotation axis ARP1, ARP2 (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

The take-off rotation axes ARP1, ARP2 are preferably parallel or in any case longitudinal to the orienting crossbar <NUM> driven by the respective power take-off <NUM>, <NUM>', <NUM>".

Such an interface is an element configured for fixing to or otherwise engaging with an orienting crossbar <NUM> or other driven rotating member so as to drive it into rotation, and may be for example a prismatic or parallelepiped- or cylinder-shaped protrusion or recess, or a flange or other male or female coupling element or other component of a joint, section or other portion of a rotating shaft.

The power input <NUM> is configured for engaging with the toothing <NUM> of the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V coming into contact therewith in at least one crown contact point PCC (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

The reduction gearbox <NUM>, <NUM>', <NUM>" comprises at least one take-off joint <NUM>, <NUM>', <NUM>", and optionally two or even more take-off joints <NUM>, <NUM>', <NUM>", each of which is configured for driving, by rotation, a respective power take-off <NUM>, <NUM>', <NUM>", wherein the two power take-offs <NUM>, <NUM>', <NUM>" extend from and/or protrude from two sides, substantially opposite to each other (<FIG>) or otherwise substantially different from each other, of the reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V.

Advantageously, each take-off joint <NUM>, <NUM>', <NUM>" comprises part of the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V and a respective power take-off <NUM>, <NUM>', <NUM>" (<FIG>).

Each take-off joint <NUM>, <NUM>', <NUM>" allows for varying the orientation in space of the rotation axis of the respective power take-off <NUM>, <NUM>',<NUM>'', referred to as ARP1, ARP2, by rotating it relative to the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V about a respective take-off rotation centre CRP1, CRP2; such rotation centres can, for example, coincide with the centre of the cross element <NUM>, with the centre of the toothing <NUM> or with the centre of the spherical surface, if any, of which the head <NUM> is a part.

Each take-off joint <NUM>, <NUM>', <NUM>" allows for varying the orientation in space of the rotation axis of the respective power take-off <NUM>, <NUM>',<NUM>'', referred to as ARP1, ARP2, by rotating it relative to the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V about the respective take-off rotation centre CRP1, CRP2 within an angle α1, α2 [alpha<NUM>, alpha<NUM>] whose absolute value is preferably between <NUM>°-<NUM> (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

The maximum angle α1, α2 [alpha1 , alpha <NUM> ] permitted by a take-off joint <NUM>, <NUM>', <NUM>" is preferably equal to or greater than <NUM> degrees, and possibly equal to or greater than <NUM> degree, two degrees, three degrees or four degrees and for example between <NUM>°-<NUM>°, <NUM>°-<NUM>°, <NUM>°-<NUM>° or still <NUM>°-<NUM>° degrees.

This arrangement facilitates the installation of the reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V making it possible to adapt the inclination -or orientation in space- of the orienting crossbars <NUM> that it drives relative to the inclination of the post <NUM> that supports it with considerable freedom of construction, eliminating or considerably reducing the costs of any cut/fill works or, more generally, earth-moving or foundation works.

The angle α1, α2 is measured in the ideal plane containing the axes ARC and ARP1 or ARC and ARP2 respectively.

The absolute value of the angle α1, α2 may also be equal to or less than <NUM>°, <NUM>°, <NUM>°, <NUM>°, <NUM>°.

Advantageously, when it comprises at least two take-off joints <NUM>, <NUM>', <NUM>" the reduction gearbox <NUM>, <NUM>', <NUM>" is configured for varying the orientation in space of the take-off rotation axis ARP1 independently of the orientation of the axis ARP2, meaning that these two orientations are two independent degrees of freedom of the reduction gearbox <NUM>, <NUM>', <NUM>" and/or that they are not bound to each other by mechanical devices.

This independence further facilitates the installation of the reduction gearbox <NUM>, <NUM>', <NUM>" allowing the inclination -i.e. orientation in space- of the orienting crossbars <NUM> driven by it and of the post <NUM> supporting it to be adapted with considerable freedom, eliminating or considerably reducing the costs of any cut/fill works or, more generally, earth-moving or foundation works.

The crown contact plane PCCor in this description means the ideal plane perpendicular to the crown rotation axis ARC and passing through at least one crown contact point PCC (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

Still according to an aspect of the invention, the distance DPC1, DPC2 along the crown rotation axis ARC, of each take-off rotation centre CRP1, CRP2 from the crown contact plane PCCor is equal to or less than twice the external radius RCext of the external toothing <NUM> of the toothed crown element.

The radius RCExt is measured between the crown rotation centre CRotCor and the outermost edge, in the radial direction, of the toothing <NUM> of the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V (<FIG>).

Preferably the distance DPC1, DPC2 is equal to or less than the external radius RCext, and even more preferably equal to or less than <NUM> times the external radius RCext, or equal to or less than <NUM> times the radius RCext, equal to or less than <NUM> times the radius RCext, equal to or less than <NUM> times the radius RCext, or equal to or less than <NUM> times the radius RCext.

Preferably the distance DPC1, DPC2 is between <NUM>-<NUM> times the radius RCext, between <NUM>-<NUM> times the radius RCext, or between <NUM>-<NUM> times the radius RCext, between <NUM>-<NUM> times the radius RCext, between <NUM>-<NUM> times the radius RCext , <NUM>-<NUM> times the radius RCext, <NUM>-<NUM> times the radius RCext, <NUM>-<NUM> times the radiusRCext, <NUM>-<NUM> times the radius RCext or <NUM>-<NUM> times the radius RCext.

These dimensional ratios, as will be explained in more detail below, reduce the overall dimensions of the reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V along the axis ARC compared to a solution with separate reduction gearbox and joint, increasing - with the same overall length of the tracker - the space that can be used to install photovoltaic panels <NUM> on the orienting crossbars <NUM> driven by the reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V.

In addition, the small distances DPC1, DPC2, which are reduced by particularly suitable take-off joints <NUM>', <NUM>" comprising cardan or ball joints or Rzeppa joints, allow the stresses of the take-off joints <NUM>', <NUM>" to be discharged closer to the axis of the respective post <NUM>, advantageously stressing it more in terms of compression and less in terms of bending.

Advantageously, each take-off joint <NUM>, <NUM>', <NUM>" is at least partially and possibly only partially contained in the housing <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>v. According to the invention, the at least one take-off joint (<NUM>, <NUM>', <NUM>") or each take-off joint (<NUM>, <NUM>', <NUM>") is at least partially contained in the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

In the reduction gearbox <NUM>, <NUM>V each take-off joint <NUM> is only partially contained in the housing <NUM>, <NUM>v because this only contains part of the power take-offs <NUM> which also form a Bowex joint (R) without completely containing the take-offs <NUM> (<FIG>, <FIG>).

In the reduction gearbox <NUM>', <NUM>III each take-off joint <NUM>' is only partially contained in the housing <NUM>', <NUM>''' because this only contains part of the toothed crown element <NUM>' which forms part of the cardan joint <NUM>' (<FIG>, <FIG>).

In the reduction gearbox <NUM>", <NUM>IV each take-off joint <NUM>" is only partially contained in the housing <NUM>", <NUM>IV because this only contains part of the power take-offs <NUM>" which form the RZeppa or ball joint without completely containing the take-offs <NUM>" (<FIG>, <FIG>).

Each power take-off <NUM>, <NUM>', <NUM>" may comprise for example a shaft section (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>), the male component (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>) or female component of a clutch.

In the embodiments of <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> each power take-off <NUM>, <NUM>', <NUM>" comprises a short shaft section with hollow square cross-sections - i.e. tubular - which forms a male projection arranged to fit, for example, into the female cavity of the end of an orienting crossbar <NUM> and engage with it so that it can be driven to rotate (<FIG>).

In other embodiments, the connection to the orienting crossbars can be made by a hollow seat or other cavity in the reduction gearbox, or by flange couplings between reduction gearbox and cross-members, or other coupling solutions.

Each joint take-off <NUM>, <NUM>', <NUM>" may comprise for example a so-called Bowex joint (R) (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>), a cardan joint (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>), a ball or Rzeppa joint (R) (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

A Bowex-type joint (R) in this description means a joint comprising:.

In the Bowex-type joint (R) according to the present description, the male element may possibly but not necessarily slide along the axis of the female seat (<FIG>,<FIG>).

In other embodiments not shown, each take-off joint <NUM>, <NUM>', <NUM>" may comprise, for example, a Birfield joint, a Tracta joint, a Weiss joint, a tripod joint, a double or multiple cardan joint, a Thompson joint, a Malpezzi joint or, more generally, a homokinetic joint, a non-homokinetic joint or other articulated joint capable of transmitting a driving torque between two shafts while allowing the latter to vary their orientation in space.

As in the embodiment of <FIG> the shaft section belonging to each power take-off <NUM> can engage with the toothed crown element <NUM> by means of a gear.

For this purpose, at or near the end of each power take-off <NUM> a toothing <NUM> is obtained comprising, for example, an external toothing with a corresponding inner toothing <NUM> obtained in the through-hole <NUM> or in any case within the toothed crown element <NUM>.

The teeth can form appropriately rounded ridges, for example with arc-of-a-circle edges, when viewed in a direction perpendicular to their respective rotation axis ARP1, ARP2, and such that the shaft sections belonging to each power take-off <NUM> can tilt in space and vary their orientation in their space and in that of their respective rotation axis ARP1, ARP2 relative to the toothed crown element <NUM>.

The homo-kinetic take-off joints <NUM>, <NUM>', <NUM>" , whether Bowex (R), Rzeppa (R) or other types, make it advantageously possible to rotate the orientation crossbars <NUM>, <NUM>A, <NUM>B to the left and right of the reduction gearbox while keeping the same inclination and avoiding angular misalignment while rotating them and thus introducing errors in the positioning of the photovoltaic panels <NUM> located on one or more parts of the tracker.

As, for example, in the embodiment of <FIG> the length Lbwx, according to the direction parallel to the crown rotation axis ARC, of the inner toothing <NUM> obtained in the inner through-cavity of the toothed crown element <NUM> is preferably between <NUM>-<NUM> times the external radius RCext of the external gearing <NUM> of the toothed crown element.

More preferably the length Lbwx is between <NUM>-<NUM> times the radius RCext, or between <NUM>-<NUM> times, <NUM>-<NUM> times the radius RCext.

These dimensions of the length Lbwx allow the shaft sections belonging to each power take-off <NUM> not only to vary their orientation in space relative to the toothed crown element <NUM> but also to slide along the through cavity <NUM> of the element <NUM>.

Such sliding is preferably limited by an annular edge <NUM> or other axial stops that prevent the elements <NUM> from completely slipping out of the toothed crown <NUM> detaching from it.

As for example in the embodiment of <FIG>, <FIG>, <FIG>the shaft section belonging to each power take-off <NUM>' can engage with the toothed crown element <NUM>' forming a single, double or multiple cardan joint.

For this purpose, the end of the shaft section belonging to each power take-off <NUM>' closest to the toothed crown centre <NUM>' can form a first pair of coaxial holes <NUM>, an end of the toothed crown element <NUM>' can form a second pair of coaxial holes <NUM> and a cross-shaped element <NUM> can fit into both pairs of holes <NUM>, <NUM> so that it can rotate on itself in the holes and make a cardan joint.

Advantageously, the cross vaults of the two cardan joints of the reduction gearbox <NUM>' are angularly offset by approximately <NUM>° so that their assembly is homokinetic.

As for example in the embodiment of <FIG>, <FIG>, <FIG> the shaft section belonging to each power take-off <NUM>" can engage with the toothed crown element <NUM>" forming a Rzeppa joint or more generally a ball joint.

For this purpose, the end of the shaft section belonging to each power take-off <NUM>" closest to the toothed crown centre <NUM>" may form a male head <NUM> for example in the form of a spherical segment, on which a first plurality of grooves or splines <NUM> are cut, extending in directions parallel to the respective axis ARP1, ARP2 and serving as the tracks of the balls <NUM>.

In the through cavity <NUM> of the toothed crown element <NUM>" a seat may be obtained, for example, in the form of a portion of a spherical surface on which a second plurality of grooves or splines <NUM> are obtained, which extend in directions parallel to the axis ARC and also serve as tracks of the balls <NUM>.

When the male head is inserted into its respective seat in the toothed crown element <NUM>", a plurality of balls <NUM> -such as six- and possibly a cage <NUM> are placed between them to hold the balls <NUM> in position.

Each ball <NUM> is inserted into both a track <NUM> and a corresponding track <NUM> allowing the toothed crown element <NUM>" and the respective power take-offs <NUM>" to apply drive torques to each other and thus forming a Rzeppa joint (R) or more generally a ball joint.

The shaft of the power input <NUM> is configured for driving the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V rotating on itself around an axis AXP preferably and substantially perpendicular to the axis ARC or otherwise transverse or bent and not substantially parallel or not coincident with the axis ARC (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>).

Two axes in space in this description are considered substantially parallel or coincident if an ideal plane passing through one of them and intersecting the other axis at the shortest possible distance forms an angle with the other axis equal to or less than <NUM>°, more preferably equal to or less than <NUM>° or <NUM>° or <NUM>° or <NUM>°.

Preferably the shaft of the power input <NUM> is at least partially contained in the housing <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V.

The reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V preferably includes an actuator <NUM>, <NUM>' configured for driving one or more of the respective power inputs <NUM>, driving them, for example, rotating the shaft of the power input <NUM> in question.

The actuator may comprise an electric, pneumatic or hydraulic motor <NUM> (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>) or a bar or other connecting drive shaft <NUM>' configured for transmitting motion between the shafts or other components of the power inputs <NUM> of two different reduction gearboxes <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, wherein the power inputs <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V of each of said reduction gearboxes are configured for actuating, e.g., respective orienting crossbars <NUM> substantially parallel - according to a horizontal direction - to the orienting crossbars <NUM> actuated by the power take-offs <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V of the other reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, (<FIG>, <FIG>).

According to a vertical direction, on the other hand, the orienting crossbars <NUM> driven by the two reduction gearboxes <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V are completely free, compared to the orienting crossbars <NUM> of the other reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, to adapt conveniently to the shape of the underlying ground.

In other words, the bar or other connecting drive shaft <NUM>' allows the driving torque to be transmitted between the power inputs <NUM> of two different reduction gearboxes <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V belonging to two different rows of photovoltaic panels <NUM> and orienting crossbars <NUM>, <NUM>A, <NUM>B.

The connecting rod or other drive shaft <NUM>' allows two or more reduction gearboxes <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V to be driven by a single motor <NUM>.

The housing, <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V, the rotating shaft of the power input <NUM>, the power take-offs <NUM>, <NUM>', <NUM>", , <NUM>III, <NUM>IV, <NUM>V, the take-off joints <NUM>, <NUM>', <NUM>", the balls <NUM> may be for example made of steel or other suitable metal materials.

The embodiments of <FIG>, wherein the reduction gearbox is provided with a single take-off joint <NUM>, <NUM>', <NUM>" are simpler and cheaper to produce than, for example, the embodiments of <FIG>.

Their power take-off <NUM>III, <NUM>IV, <NUM>V can be obtained on a toothed crown element <NUM>III, <NUM>IV, <NUM>V which can be a simple single piece fixed without joints or other articulations to the housing <NUM>III, <NUM>IV, <NUM>V or in any case to the rest of the reduction gearbox, in such a way that the power take-off rotation axis coincides with the toothed crown axis ARC and with that of the housing <NUM>III, <NUM>IV, <NUM>V.

The toothed crown element <NUM>III, <NUM>IV, <NUM>V may be made, for example, as a simple single piece, preferably tubular or otherwise hollow, possibly provided with appropriate shoulders and suitably shaped sections (<FIG>).

The crown contact plane PCCor or more generally the housing <NUM>III, <NUM>IV, <NUM>V may be inclined relative to the vertical by interposing between the post <NUM> and the reduction gearbox <NUM>III, <NUM>IV, <NUM>V a suitable adapter such as a slotted bracket or a wedge-shaped adapter which allows to give the reduction gearbox <NUM>III, <NUM>IV, <NUM>V and the axis ACR in question the desired inclination.

The power input <NUM>III, <NUM>IV, <NUM>V or more in general the toothed crown element <NUM>III, <NUM>IV, <NUM>V may have an axial length, according to the axis ARC, for example substantially equal to the axial length of the power take-off <NUM>', <NUM>", <NUM>, respectively so as to make the axial footprint of the reduction gearbox <NUM>III, <NUM>IV, <NUM>V substantially symmetrical relative to the plane PCCor.

This makes it possible to mount orienting crossbars <NUM> of the same length on both sides of the reduction gearboxes <NUM>III, <NUM>IV, <NUM>V, reducing the number of prefabricated crossbars that a solar tracker manufacturer must keep in stock or otherwise in the catalogue and thus reducing production, management and structural costs.

In alternative, the power take-off <NUM>III, <NUM>IV, <NUM>V or more generally the toothed crown element <NUM>III, <NUM>IV, <NUM>V may have an axial length, according to the axis ARC, noticeably less than the axial length respectively of the power take-off <NUM>', <NUM>", <NUM>, so as to reduce the axial footprint of the reduction gearbox <NUM>III, <NUM>IV, <NUM>V and make it easier to mount more photovoltaic panels on a same orienting crossbar or in any case in the solar system, with the same overall length of the latter.

Advantageously, the at least one or the at least two take-off joints <NUM>, <NUM>', <NUM>" are configured for allowing, at least in one operating condition among many, the two rotation axes ARP1, ARP2, around which the two respective power take-offs <NUM>, <NUM>', <NUM>" rotate or in any case along which the two respective power take-offs extend, to be arranged substantially coaxial to each other.

This facilitates the assembly of the reduction gearboxes <NUM>, <NUM>', <NUM>" and of the solar tracker systems <NUM>, <NUM>', <NUM>" to which they belong, allowing the reduction gearboxes <NUM>, <NUM>', <NUM>" to adapt more conveniently to a greater variety of grounds.

As already partially mentioned above, each power take-off <NUM>, <NUM>', <NUM>" can be fixed to one end of a crossbar <NUM> of a solar tracker system <NUM>, <NUM>', <NUM>" so as to drive the crossbar <NUM> rotating it around its own longitudinal axis, which preferably coincides with the axis ARP1, ARP2 (<FIG>) or parallel thereto.

In some embodiments, the rotation axis of the crossbar <NUM> may not coincide with its own longitudinal axis, but be shifted -for example, parallel- above it, to coincide with or at least come close to the barycentre axis of the rotating part of the solar tracker.

Each orienting crossbar <NUM> of the system <NUM>, <NUM>', <NUM>" may be between <NUM>-<NUM> metres in length, and more preferably between <NUM>-<NUM> metres, between <NUM>-<NUM> metres, between <NUM>-<NUM> metres, between <NUM>-<NUM> metres or between <NUM>-<NUM> metres.

The system <NUM>, <NUM>', <NUM>" comprises a plurality of uprights <NUM> made for example as metal or concrete posts, on which one or more crossbars <NUM> rest.

Each orienting crossbar <NUM> of the system <NUM>, <NUM>', <NUM>" extends preferably and approximately parallel to the average course of the ground (<FIG>, <FIG>).

A plurality of photovoltaic panels <NUM> is fixed to each orienting crossbar <NUM>.

These panels <NUM> preferably form a single row (<FIG>,<FIG>) but may possibly form more than one row longitudinal to the respective crossbar <NUM>, in the already described "vertical" or "landscape" configurations.

Each reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V can be fixed e.g. on the upper end of an upright or other post <NUM> of the solar tracker system <NUM>, <NUM>', <NUM>" by means of suitable fixing brackets.

Each reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V described above allows two orienting crossbars <NUM> with different orientations and inclinations in space to be connected and driven in rotation; each orienting crossbar <NUM> will therefore preferably be more or less parallel to the average course of the ground surface over a shorter length (<FIG>,<FIG>).

This means that a row of solar panels <NUM> and solar trackers can follow the course of the ground by describing also a broken line of various shapes, allowing the orienting crossbars <NUM> and the various straight sections of the panels <NUM> to form angles β [beta], β1, β2. βN with each other that are relatively accentuated (<FIG>, <FIG>) and which for example can be up to <NUM>° degrees, <NUM>° degrees or even more: in the solar trackers <NUM>, <NUM>', <NUM>", the relationship<MAT> is true.

In other words, the broken line with which the orienting crossbars <NUM> and the various straight sections of the panels <NUM> of the system <NUM>, <NUM>', <NUM>" follow the course of the ground best, under the same conditions - e.g. irregularities in the ground surface, costs of the cut/fill works or other earth-moving works, costs for compensating undulations and irregularities in the ground with the above-ground length of the posts <NUM>, length of the orienting crossbars <NUM> - must be much less straight than the line formed by the orienting crossbars <NUM> of a same row of photovoltaic panels <NUM> of a solar tracker of the known-type, or in any case it creates the same broken line at lower costs and footprint.

Furthermore, since, as said, the distance DPC1, DPC2 along the crown rotation axis ARC, of each take-off rotation centre CRP1, CRP2 from the crown contact plane PCCor is equal to or less than twice the external radius RCext of the external toothing <NUM> of the toothed crown element, the ends of two orienting crossbars <NUM> connected to a same reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V may be closer to the known trackers provided with joints separated by reduction gearboxes thus creating a more compact solution which -with the same overall length - makes it possible to install more photovoltaic elements <NUM> on a same row.

The possibility, at least in some embodiments, of mutually orienting in space the axes ARC, ARP1, ARP2, the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V and the power take-offs <NUM>, <NUM>', <NUM>" with almost total freedom, at least within the above-mentioned wide margins, allows to install and commission the posts <NUM> and the orienting crossbars <NUM> easily and cost-effectively.

A solar tracker system <NUM>, <NUM>', <NUM>" may comprise not only two but also, for example, three, four, five, six, seven, eight, nine, ten, fifteen, twenty or even several orienting crossbars <NUM> arranged in a single row one after the other and connected two by two by means of a reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V.

In such case, the reduction gearboxes can be driven by a same motor/actuator by a transmission system or by separate actuators operating synchronously.

An example of the installation, operation and use of the reduction gearboxes <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V and the solar tracker systems <NUM>, <NUM>', <NUM>" described above is now described.

The driven motor -e.g. electric- <NUM> makes the screw-profile shaft of the power input <NUM> rotate, which in turn makes the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V rotate around the axis ARC relative to the housing <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V and therein.

The rotation of the toothed crown element on itself <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V makes the power take-offs <NUM>, <NUM>', <NUM>" rotate about their own longitudinal axes ARC1, ARC2 thereby rotating the orienting crossbars <NUM> and the photovoltaic panels fixed thereto, and changing the inclination of the panels <NUM> themselves, for example to optimise them relative to the direction of sun rays and increase the electricity produced by the panels <NUM>.

In the reduction gearbox <NUM> the toothed crown element <NUM> rotates the power take-offs <NUM> by the inner toothing <NUM> which engages and makes the external toothing <NUM> of the power take-offs <NUM> rotate around the axis ARP1, ARP2.

In the reduction gearbox <NUM>' the toothed crown element <NUM>' rotates the power take-offs <NUM>' and drives the cross-shaped elements <NUM> to rotate which in turn make the power take-offs <NUM>' rotate around the axis ARP1, ARP2.

In the reduction gearbox <NUM>" the toothed crown element <NUM>" makes the power take-offs <NUM>" rotate making the grooves or splines <NUM>, which are formed in the female housing that accommodates the male heads <NUM> of the power take-offs <NUM>", rotate.

The grooves or splines <NUM> make the balls <NUM> rotate around their respective axes ARP1 or ARP2, which balls <NUM> make, in turn, the grooves or splines <NUM> formed on the male head <NUM> of each power take-off <NUM>" rotate around these axes.

The embodiments described above are susceptible to numerous modifications and variants, without departing from the scope of the present invention.

For example, the balls <NUM> of a joint <NUM>" can even be more or less than six, e.g. they can be two, three, four, five, seven, eight, nine, ten, twelve or even <NUM> and more balls <NUM>.

The power input <NUM> can engage with the toothed crown element <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V to form not only a worm gear mechanism but also, for example, a cam mechanism, a parallel or inclined axis gear, a tilted plane mechanism, a leverage mechanism or others.

More generally, in a further aspect thereof, the invention relates to a reduction gearbox (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) comprising a housing (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V), at least one toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V), a power inlet (<NUM>), at least two power take-offs (<NUM>, <NUM>', <NUM>",<NUM>III, <NUM>IV, <NUM>V), at least one take-off joint (<NUM>, <NUM>', <NUM>");
wherein:.

According to the invention, the at least one take-off joint (<NUM>, <NUM>', <NUM>") or each take-off joint (<NUM>, <NUM>', <NUM>") is at least partially contained in the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V).

A solar tracker system according to the invention may comprise a single reduction gearbox <NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V or a plurality thereof, for example two, three, four, five, six, seven, eight, nine, ten, eleven, fifteen, twenty, forty of them arranged one after the other so as to form a single row or several rows parallel or longitudinal to each other.

A solar tracker system according to the invention may comprise not only a single row of photovoltaic panels <NUM> fixed on a single row of orienting crossbars <NUM> (<FIG>,<FIG>) but also several rows of photovoltaic panels <NUM> fixed on several rows of orienting crossbars <NUM>, wherein such rows are substantially parallel or longitudinal to each other (<FIG>) while still following with broken lines the undulations and other irregularities of the ground as for example in <FIG>, <FIG>.

A solar tracker system according to the invention may comprise a plurality of orienting crossbars <NUM> of substantially the same length or of different lengths.

A solar tracker system according to the invention may comprise a plurality of uprights or other posts <NUM>, for example three, four, five, six, seven, eight, nine, ten, eleven, fifteen, twenty, forty of them arranged one after the other so as to form a single row or several rows parallel or longitudinal to each other.

Every reference in this description to "an embodiment", "an example of embodiment" means that a particular characteristic or structure described in relation to such embodiment is comprised in at least one embodiment of the invention and in particular in a particular variant of the invention as defined in a main claim.

The fact that such expressions appear in various passages of the description does not imply that they are necessarily referred solely to the same embodiment.

In addition, when a feature, element or structure is described in relation to a particular embodiment, it is observed that it is within the competence of the person skilled in the art to apply such feature, element or structure to other embodiments.

Numerical references which only differ in terms of different superscripts <NUM>', <NUM>", <NUM>III unless specified otherwise indicate different variants of an element with the same name.

Furthermore, all of the details can be replaced by technically equivalent elements.

In practice, the materials used, as well as the dimensions thereof, can be of any type according to the technical requirements.

It must be understood that an expression of the type "A comprises B, C, D" or "A is formed by B, C, D" also comprises and describes the particular case in which "A consists of B, C, D".

The expression "A comprises a B element" unless otherwise specified is to be understood as "A comprises one or more elements of B".

References to a "first, second, third,. n-th entity" have the sole purpose of distinguishing them from each other but the indication of the n-th entity does not necessarily imply the existence of the first, second. (n-<NUM>)th entity.

Claim 1:
Reduction gearbox (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) comprising a housing (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V), at least one toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V), a power input (<NUM>), at least two power take-offs (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V), at least one take-off joint (<NUM>, <NUM>', <NUM>");
wherein:
- the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) forms a gear toothing (<NUM>);
- the power input (<NUM>) is configured for driving the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V);
- the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) is configured for driving both power take-offs (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) by rotating about itself around a crown rotation axis (ARC);
- each power take-off (<NUM>, <NUM>', <NUM>") comprises a rotating interface configured for rotating about itself about a take-off rotation axis (ARP1, ARP2) and to engage and drive a shaft or other driven rotating element;
- the power input (<NUM>) is configured for engaging with the toothing (<NUM>) of the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) coming into contact therewith in at least one crown contact point (PCC);
- the at least one take-off joint (<NUM>, <NUM>', <NUM>") allows to vary the orientation in space of at least one take-off rotation axis (ARP1, ARP2) by rotating it relative to the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V) around a respective take-off rotation centre (CRP1, CRP2); characterized in that:
- the distance (DPC1, DPC2), according to the crown rotation axis (ARC), of each take-off rotation centre (CRP1, CRP2) from the crown contact plane (PCCor) is equal to or less than twice the external radius (RCext) of the toothing (<NUM>) of the toothed crown element (<NUM>, <NUM>', <NUM>", <NUM>III, <NUM>IV, <NUM>V), wherein the crown contact plane (PCCor) is the ideal plane perpendicular to the crown rotation axis (ARC) and passing through the at least one crown contact point (PCC);
- the at least one take-off joint (<NUM>, <NUM>', <NUM>") or each take-off joint (<NUM>, <NUM>', <NUM>") is at least partially contained in the toothed crown element (<NUM>, <NUM>', <NUM>",<NUM>III, <NUM>IV, <NUM>V).