WO2012098565A2

WO2012098565A2 - Kinematic mechanism for bi-axial follower assemblies

Info

Publication number: WO2012098565A2
Application number: PCT/IT2011/000014
Authority: WO
Inventors: Gianluca DI FRANCESCO
Original assignee: Dimensione Solare S.R.L.
Priority date: 2011-01-18
Filing date: 2011-01-18
Publication date: 2012-07-26
Also published as: SMAP201300091A; WO2012098565A3; WO2012098565A8

Abstract

A kinematic mechanism (1) for bi-axial follower assemblies (2) of the type that comprises a fixed footing (3) for supporting a motor drive (4), which defines substantially an azimuth rotation by an angle ϕ, designed to support, by means of an adapted frame (5), a component (6) to be oriented. The footing (3) comprises a column (7) and a beam (8) which are fixed and mutually incident; the free end (10) of the column (7) comprises a first spherical joint (11), which has three degrees of freedom of the rotary type, for connection to a rod (12) of the frame (5). The end portion (13) of the beam (8) comprises a second spherical joint (14) for connection to a bar (15) of the frame (5). The tips (16, 17) of the rod (12) and of the bar (15) are mutually connected by means of a third spherical joint ( 18). The component (6) to be oriented is coupled stably to the rod (12), the rotation of the rod (12), imposed by the motor drive (4), determining a rotation of the component (6) by the azimuth angle θ and by a tilt angle θ along a predefined curved line.

Description

KINEMATIC MECHANISM FOR BI-AXIAL FOLLOWER

ASSEMBLIES

Technical field

The present invention relates to a kinematic mechanism for bi-axial follower assemblies.

Background art

Follower assemblies or trackers are used for various applications: solar trackers, whose purpose is to keep a specific surface constantly aligned (or correctly inclined) with respect to the rays of the sun throughout the day, are particularly important; the field of telecommunications, too, resorts to specific trackers aimed at maintaining the correct alignment of an antenna or other component with a satellite or an astronomical feature that constitutes a reference for correct transceiving (for example the aiming of parabolic antennas); applications in electric power generators of the type operating according to the "solar Stirling" cycle, in which a fluid undergoes successive changes of state as a consequence of heating obtained by utilizing appropriately concentrated solar radiation, are equally important.

With particular reference to photovoltaic panels, it is in fact appropriate to note that fixed panels, for example installed on the ground or on roofs, have an optimum orientation only for a few hours throughout the day.

The adoption of a follower assembly determines a continuous and constant change in the inclination and orientation of the solar panels, keeping them constantly in the condition of optimum irradiation, with consequent maximization of the conversion efficiency of the entire photovoltaic system.

It is in fact important to note that the sun, with respect to a fixed terrestrial reference, moves from east to west through the day, at different heights with respect to the line of the equator (a height variation that can be observed both during a single day and during the year). Fixed photovoltaic panels require such an arrangement as to average constantly the irradiation conditions (throughout the day and throughout the year): the optimum orientation of a panel is to the south, since this optimizes the angle of incidence of the solar rays, which move symmetrically from east to west with respect to the south. Merely by way of example, for the latitudes at which Italy is located, the angle of inclination of the panel with respect to the horizontal (tilt angle Θ) is comprised between 29° (southern Italy) and 32° (northern Italy). This tilt angle Θ corresponds to the average height of the sun above the horizon during the day and during the year.

Moving the photovoltaic panels by means of follower assemblies ensures that the optimum angle of incidence of the solar radiation on the surface of the panel is maintained: in practice these assemblies orient such panel in the direction of the sun.

The ideal movement, by means of these follower assemblies, is the one that occurs according to two rotational axes (a first controlled rotation at an azimuth angle φ and a second controlled rotation at a tilt angle Θ), arranging the solar panel substantially always perpendicular to the sun.

By means of adapted controlled motor drives it is thus possible to maintain the ideal alignment throughout the day and throughout the year, producing increases in the conversion efficiency of the system that are even 35% higher than in a system with fixed panels. Efficiency increases significantly at times of lower irradiation, i.e., when poor efficiencies in the production of electric power are obtained with fixed installations.

Known bi-axial follower assemblies comprise respective controlled actuators, which are designed to move the photovoltaic panels respectively according to the azimuth angle φ and the tilt angle Θ.

These controlled actuators (generally driven by by an adapted control and management unit) have high costs, owing to the fact that each individual movement must be defined precisely by the rule of motion imposed by the control and management unit: these are, therefore, sophisticated electronic components managed by dedicated and appropriately implemented software.

The manufacturing and production cost of known types of assemblies is very high due to the use of sophisticated components: for example, the actuators can comprise electric motors of the brushless type and the control and management unit is generally constituted by a processing device of the type of a PLC or the like.

The adoption of this type of components makes the known types of follower assemblies particularly heavy and bulky, limiting their installation only to structures that are particularly strong or requiring the provision of specific reinforced footings.

The maintenance of known electronically, controlled follower assemblies is particularly complicated and necessarily requires the presence of specialized technicians.

Moreover, any repair/replacement of parts is particularly expensive and often requires a new implementation of the entire control logic system.

It is evident that the time required for repair/replacement of a component is long as well, with consequent disservice of the system, which during this time interval can operate only under reduced-efficiency conditions (correct orientation is not possible).

Disclosure of the invention

The aim of the present invention is to solve the drawbacks described above, by proposing a kinematic mechanism for bi-axial follower assemblies of an essentially mechanical type.

Within this aim, an object of the invention is to propose a kinematic mechanism for bi-axial follower assemblies that is lightweight and compact.

Another object of the invention is to propose a kinematic mechanism for bi-axial follower assemblies that is adapted to maintain a correct alignment with the specific reference according to the two angles, the azimuth angle φ and the tilt angle Θ, by resorting to a single motor. Another object of the invention is to propose a kinematic mechanism for bi-axial follower assemblies that is low-weight and has small dimensions.

Another object of the invention is to propose a kinematic mechanism for bi-axial follower assemblies that is simple and quick to maintain and repair.

Another object of the invention is to propose a kinematic mechanism for bi-axial follower assemblies that is adapted to ensure a high conversion efficiency in case of installation in a photovoltaic system.

A further object of the present invention is to provide a kinematic mechanism for bi-axial follower assemblies that has a low cost, is relatively simple to provide in practice and is safe in application.

This aim and these objects, as well as others that will become better apparent hereinafter, are achieved by a kinematic mechanism for bi-axial follower assemblies of the type that comprises a fixed footing for supporting a motor drive, which defines substantially an azimuth rotation at an angle φ, designed to support, by means of an adapted frame, a component to be oriented, characterized in that said footing comprises a column and a beam which are fixed and mutually incident, the free end of said column comprising a first spherical joint, which has 3 degrees of freedom of the rotary type, for connection to a rod of said frame, the end portion of said beam comprising a second spherical joint for connection to a bar of said frame, the tips of said rod and of said bar being mutually connected by means of a third spherical joint, the component to be oriented being coupled stably to said rod, the rotation of said rod, imposed by said motor drive, determining a rotation of the component according to the azimuth angle φ and according to a tilt angle Θ along a predefined curved line.

Brief description of the drawings

Further characteristics and advantages of the invention will become better apparent from the detailed description that follows of a preferred but not exclusive embodiment of the kinematic mechanism for bi-axial follower assemblies according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a schematic side view of a first possible embodiment of a kinematic mechanism for bi-axial follower assemblies according to the invention;

Figure 2 is a schematic front view of the embodiment of Figure 1 ; Figure 3 is a schematic side view of a second possible embodiment of a kinematic mechanism for bi-axial follower assemblies according to the invention;

Figure 4 is a schematic front view of the embodiment of Figure 3;

Figure 5 is a schematic side view of a third possible embodiment of a kinematic mechanism for bi-axial follower assemblies according to the invention;

Figure 6 is a schematic front view of the embodiment of Figure 5;

Figure 7 is a schematic plot of the predefined curved lines of a kinematic mechanism for bi-axial follower assemblies according to the invention as a function of the variation of the dimensions of the components;

Figure 8 is a schematic view of the arrangement of the alignments of a function of the cardinal points.

Ways of carrying out the invention

With reference to the figures, the reference numeral 1 generally designates a kinematic mechanism for bi-axial follower assemblies.

The kinematic mechanism 1 for bi-axial follower assemblies 2 comprises a fixed footing 3 for supporting a motor drive 4, which defines an azimuth rotation according to an angle Θ.

The footing 3 is designed to support, by means of an adapted frame 5, a component 6 to be oriented.

The footing 3 comprises a column 7 and a beam 8, which are fixed and mutually incident at the point of incidence 9.

The free end 10 of the column 7 comprises a first spherical joint 1 1, which is a joint that has 3 degrees of freedom of the rotary type.

The first spherical joint 1 1 is designed for connection of the end of the column 7 to a rod 12 of the frame 5.

The end portion 13 of the beam 8 comprises a second spherical joint 14 for the connection of the beam 8 to a bar 15 of the frame 5.

The tips 16 of the rod 12 and the tips 17 of the bar 15 are mutually connected by means of a third spherical joint 18.

The component 6 to be oriented is therefore coupled stably to the rod

12.

The rotation of the rod 12, imposed by the motor drive 4 about the axis of the column 7, determines a rotation of component 6 according to the azimuth angle φ and according to a tilt angle Θ along a predefined curved line.

In particular, it should be specified that the rod 12 has a length A, the bar 15 has a length B, the first spherical joint 1 1 has spatial coordinates X_1? Yi and Zi and the second spherical joint 14 has spatial coordinates X₂, Y₂ and Z₂.

These coordinates refer, according to the embodiments shown in the accompanying figures, to a Cartesian reference plane whose origin is located at the point of contact 9 between the column 7 and the beam 8.

According to these parameters, the predefined curved line followed by the third spherical joint 18 and therefore also the orientation of the component 6 is constituted by the intersection of the following equations

J (x - x ² + (Y - Y,)² + (z- z₁y = A

KX - X₂)² + (Y - Y₂)² + (Z- Z₂)² = B

This is substantially a system constituted by the equations of two spheres.

The first equation represents the sphere- that is centered at the first spherical joint 1 1 and has a radius with a length A (which corresponds to the length of the rod 12).

The second equation represents the sphere that is centered at the second spherical joint 14 and has a radius with a length B (which corresponds to the length of the bar 15).

The variation of the positions of the respective centers and the variation of the respective radii of the two spheres determines a variation of the curve that represents their intersection and constitutes the predefined reference curve along which the third joint 18 moves during the operation of the kinematic mechanism 1 , the correct orientation of the component 6 throughout the day and throughout the year being providable by means of such curve.

The dimensions of the footing 3 and of the frame, i.e., the length A of the rod 12, and the length B of the bar 15 and the coordinates of the first joint 1 1 and of the second joint 14, determine the shape of the, predefined curved line in accordance with the ideal curved line, known as a function of the geographical coordinates of installation of the assembly 2.

According to a particular constructive solution of unquestionable interest in practice and in application, the bar 15 is constituted by a linear actuator (a solution not shown in the accompanying figures) for the controlled variation of its length B, with the consequent possibility of adjusting and modifying the shape of the predefined curved line: the variation of the parameter B in fact alters the behavior of the curve, this opportunity being particularly advantageous since it ensures the adjustment of the assembly even after its installation.

The actuator can be constituted by two telescopic tubular elements designed to slide in relation to each other due to the action of a specific motor or actuated manually by an operator (if this adjustment is intended exclusively for simple fine adjustments).

According to a further embodiment, the possibility is noted to interpose between the bar 15 and the third spherical joint 18 a transverse slider (not shown in the accompanying figures) for a carriage that performs a translational motion along the direction Z (with particular reference to the Cartesian system according to which the equations cited earlier are identified).

The translational motion of the third spherical joint 18, due to the sliding of the carriage within the slider, produces the adjustment and modification of the shape of the predefined curved line.

The adoption of both described embodiments in one kinematic mechanism 1 in order to increase the possibilities of adjustment is not excluded.

It is important to point out that the bi-axial follower assembly 2, provided with the kinematic mechanism 1 according to the invention, constrains and supports a component 6 to be oriented of the type of a photovoltaic panel, a thermal solar panel, an antenna, a generator of the type known as "solar Stirling", a telescope, an optical device, a transceiver device, and the like.

The possibility of adopting the assembly 2 in different specific applications as a function of the requirements imposed by such applications is not excluded.

With particular reference to a constructive possibility of unquestionable effectiveness, the motor drive 4 is a gear motor that is controlled by an adapted control and management unit, which comprises an astronomical clock for adjusting the speed and scope of rotation (azimuth angle φ) throughout the day and throughout the year as a function of the installation latitude.

This embodiment allows simple and immediate maintenance, since the gearmotor and its components are easily commercially available (in case of replacement and/or repair) and the intervention of a highly specialized technician is not required since these elements are particularly simple and widespread (and therefore- any technician will be able to perform the necessary operations for repair, maintenance and/or replacement).

Moreover, gearmotors also have a significantly lower cost than the controlled brushless motors used in known types of follower assembly: this leads to a lower cost of the assembly 2 provided with the kinematic mechanism 1 (also in view of the fact that traditional assemblies generally comprise two distinct brushless motors) and considerable simplicity in construction and installation.

According to a possible embodiment, the footing 3 comprises a supporting pillar 19 which is jointly connected to the installation surface (this solution is shown in the examples of Figures 5 and 6).

Other embodiments are instead provided with a footing 3 which comprises a supporting structure provided with at least two feet 20 which are jointly connected to the installation surface. The accompanying figures illustrate constructive examples provided with four supporting feet 20 (this solution is shown in the examples of Figures 1 and 2) and with three supporting feet 20 (this solution is shown in the examples of Figures 3 and 4)·

In order to identify the correct method for the production and dimensioning of a kinematic mechanism 1 for bi-axial follower assemblies 2 it is necessary to analyze individually the consecutive steps that compose it.

It is specified that the method is suitable exclusively for the dimensioning of kinematic mechanisms 1 for assemblies 2 which comprise a fixed footing 3, comprising a column 7 and a beam 8 which are fixed and mutually incident (at a point 9).

The footing 3 is designed to support a motor drive 4, which in turn defines an azimuth rotation with an angle φ.

The footing 3 and the motor drive 4 support the component 6 to be oriented by means of an adapted frame 5.

Such frame comprises a rod 12, which is associated, by means of a first spherical joint 1 1, with the end 10 of the column 7, and a bar 15, which is associated, by means of a second spherical joint 14, with the end portion 13 of the beam 8.

The tips 16 of the rod 12 and 17 of the bar 15 are mutually connected by means of a third spherical joint 18.

With particular reference to this embodiment, it is specified that the method for dimensioning the kinematic mechanism 1 consists in:

- determining the geographical coordinates of the site of future installation of the follower assembly 2 in order to identify the ideal curved line that the follower assembly 2 shall follow;

- obtaining the parametric equation, as a function of the parameters that constitute the length A of the rod 12 of the frame 5, the length B of the bar 15 and the coordinates of the first joint 1 1 and of the second joint 14, respectively X_1?

and X₂, Y₂ and Z₂, as an equation that resolves the following system of equations

J (X - Xi)² + (Y - Y ² + (Z- Z,)² = A

L (X - X₂)² + (Y - Y₂)² + (Z- Z₂)² = B

- determining the value of the parameters, i.e., the length A of the rod 12, the length B of the bar 15 and the coordinates of the first joint 1 1 and of the second joint 14, respectively Xi, Yj and Zi and X₂, Y₂ and Z₂, so that such parameters are adapted to allow the superimposition of the curved line identified by the parametric equation and the ideal curved line, obtaining the predefined curved line of the assembly 2;

- providing a footing 3 and a frame 5 provided with a column 7, with a beam 8, with a rod 12 and with a bar 15 whose length is identical to the previously calculated one and with the first joint 1 1 and the second joint 14 in the points identified by the previously calculated coordinates.

With particular reference to the dimensioning method described above, it is specified that the bar 15 can comprise a linear actuator for controlled variation of its length B: this determines the possibility of adjustment and modification of the shape of the predefined curved line and therefore of the orientation of the component 6.

Also within the scope of the operations and steps described in the method cited above, the possibility is noted of interposing between the bar 15 and the third spherical joint 18 a transverse slider for a carriage that performs a translational motion along the direction Z.

The translational motion of the third spherical joint 18 also causes the adjustment and modification of the shape of the predefined curved line and therefore of the orientation of the component 6.

The actuation of the motor drive 4 causes a rotation of the column 7 according to a predefined rotation angle β. With respect to the installation plane, the rod 12 has an inclination in a specific inactive configuration which is equal to an angle a.

The rotation of the motor drive 4 causes a continuous reciprocal spatial movement of the rod 12 and of the bar 15, with consequent variation of the azimuth angle φ and of the tilt angle Θ of the component 6.

The trajectory followed by the joint 18 during its operation, defined by the dimensions of the footing 3 and of the frame 5, determines the constant optimum alignment of the component 6 with its reference (the sun, a star, a satellite).

The rotation rate of the motor drive 4 is determined by the astronomical clock that is present within the control and management unit that controls the drive 4: of course, the extent of the rotation also depends on the installation site and on the current time of the year and is therefore defined by the control and management unit.

Advantageously, the kinematic mechanism 1 according to the invention is of a substantially mechanical type and therefore is particularly strong despite its reduced weight. Conveniently, the kinematic mechanism 1 according to the invention is lightweight and compact.

Positively, the kinematic mechanism 1 according to the invention is adapted to maintain a correct alignment with the specific reference according to the two angles, the azimuth angle φ and the tilt angle Θ, by resorting to a single motor drive 4.

It is important to point out that the kinematic mechanism 1 according to the invention has particularly small dimensions and low weight and is therefore easy to install on any support (roofs, attics, ground that has not been previously reinforced, etcetera).

The possibility of making the assemblies 2 provided with the kinematic mechanism 1 according to the invention simple and quick to maintain and repair is equally positive: since the presence of a specialized technician is not necessarily required, the costs to be sustained for these activities also are distinctly low.

The present kinematic mechanism 1 , if the assembly 2 is used for installation in a photovoltaic system, is particularly adapted to ensure a high conversion efficiency.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements.

In the exemplary embodiments shown, individual characteristics, described in relation to specific examples, may actually be interchanged with other different characteristics that exist in other exemplary embodiments.

Moreover, it is noted that anything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer.

In practice, the materials used, as well as the dimensions, may be any according to requirements and to the state of the art.

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 kinematic mechanism for bi-axial follower assemblies (2) of the type that comprises a fixed footing (3) for supporting a motor drive (4), which defines substantially an azimuth rotation with an angle φ, designed to support, by means of an adapted frame (5), a component (6) to be oriented, characterized in that said footing (3) comprises a column (7) and a beam (8) which are fixed and mutually incident, the free end (10) of said column (7) comprising a first spherical joint (1 1), which has three degrees of freedom of the rotary type, for connection to a rod (12) of said frame (5), the end portion (13) of said beam (8) comprising a second spherical joint (14) for connection to a bar (15) of said frame (5), the tips (16, 17) of said rod (12) and of said bar (15) being mutually connected by means of a third spherical joint (18), the component (6) to be oriented being coupled stably to said rod (12), the rotation of said rod (12), imposed by said motor drive (4), determining a rotation of the component (6) by the azimuth angle φ and by a tilt angle Θ along a predefined curved line.

2. The kinematic mechanism according to claim 1, characterized in that said rod (12) has a length A, said bar (15) has a length B, the first spherical joint (1 1) has the spatial coordinates Xi, Yi and

and the second spherical joint (14) has the spatial coordinates X₂, Y₂ and Z₂, said predefined curved line constituting the intersection of the following equations

J (X - x ² + (Y - Y ² + (Z- z ² = A

L(X - X₂)² + (Y - Y₂)² + (Z- Z₂)² = B

3. The kinematic mechanism according to claim 2, characterized in that the dimensions of said footing (3) and of said frame (5), i.e., the length

A of the rod (12), the length B of the bar (15) and the coordinates of the first joint (1 1) and of the second joint (14), determine the shape of the predefined curved line in accordance with the ideal curved line, known as a function of the geographical coordinates of installation of the assembly (2).

4. The kinematic mechanism according to claim 3, characterized in that said bar (15) is constituted by a linear actuator for the controlled variation of its length B, with the consequent possibility of adjusting and modifying the shape of said predefined curved line.

5. The kinematic mechanism according to claim 3, characterized in that a transverse slider is interposed between said bar (15) and said third spherical joint (18) for a carriage that performs a translational motion along the direction Z, the translational motion of said third spherical joint (18) determining the adjustment and modification of the shape of said predefined curved line.

6. The kinematic mechanism according to claim 1, characterized in that said bi-axial follower assembly (2) constrains and supports a component to be oriented (6) of the type of a photovoltaic panel, a. thermal solar panel, an antenna, a generator of the type known as "solar Stirling", a telescope, an optical apparatus, a transceiving apparatus and the like.

7. The kinematic mechanism according to one or more of the preceding claims, characterized in that said motor drive (4) is a gearmotor controlled by an adapted control and management unit, which comprises an astronomical clock for adjusting the speed and extent of rotation throughout the day and throughout the year as a function of the installation latitude.

8. The kinematic mechanism according to one or more of the preceding claims, characterized in that said footing (3) comprises a supporting pillar (19) which is jointly connected to the installation surface.

9. The kinematic mechanism according to one or more of the preceding claims, characterized in that said footing (3) comprises a supporting structure which is provided with at least two feet (20) which are jointly connected to the installation surface.

10. A dimensioning method for kinematic mechanisms (1) for bi-axial follower assemblies (2), of the type comprising a fixed footing (3), comprising a column (7) and a beam (8), which are fixed and mutually incident, for supporting a motor drive (4), and defining an azimuth rotation by an angle φ, designed to support a component to be oriented (6) by means of an adapted frame (5), said frame (5) comprising a rod (12) which is associated, by means of a first spherical joint (1 1), with the end (10) of said column (7), a bar (15) associated by means of a second spherical joint (14) with the end portion (13) of said beam (8), the tips (16, 17) of said rod (12) and of said bar (13) being mutually connected by means of a third spherical joint (18), which consists in:

- determining the geographical coordinates of the future installation site of the follower assembly (2) in order to identify the ideal curved line to be followed by the follower assembly (2);

- obtaining the parametric equation, as a function of the parameters that constitute the length A of the rod (12) of said frame (5), the length B of the bar (15) and the coordinates of the first joint (1 1) and of the second joint (14), respectively (X_1?

and (X₂, Y₂ and Z₂), as an equation that solves the following system of equations

- determining the value of the parameters, length A of the rod (12), length B of the bar (15) and coordinates of the first joint (1 1) and of the second joint (14), respectively (X_ls Y] and

and (X₂, Y₂ and Z₂), adapted to allow the superimposition of the curved line identified by the parametric equation and the ideal curved line, obtained the predefined curved line of the assembly (2);

- providing a footing (3) and a frame (5) provided with a rod (12) and a bar (15) whose lengths are identical to the one calculated previously and in which the first joint (1 1) and the second joint (14) are at the points identified by the previously calculated coordinates, thus identifying the length of the column (7) and of the beam (8).

1 1. The method according to claim 10, characterized in that said bar (12) comprises a linear actuator for the controlled variation of its length B, with the consequent possibility of adjusting and modifying the shape of said predefined curved line.

12. The method according to claim 10, characterized in that a transverse slider is interposed between said bar (12) and said third spherical joint (18), for a carriage that performs a translational motion along the direction Z, the translational motion of said third spherical joint (18) adjusting and modifying the shape of said predefined curved line.