MARCANTONI, Michele (Via Baviera 6, Polverigi, Province of Ancona, I-60020, IT)
RANALLI, Antonio (Via Beato Amico 39, Montefano, Province of Macerata, I-62010, IT)
RENZI, Massimiliano (Piazza 18 Settembre 4, Recanati, Province of Macerata, I-62019, IT)
USCI, Rosalino (Via Clementina 10, Jesi, Province of Ancona, I-60035, IT)
BARTOLINI, Carlo Maria (Via Piave 24, Senigallia, Province of Ancona, I-60019, IT)
MARCANTONI, Michele (Via Baviera 6, Polverigi, Province of Ancona, I-60020, IT)
RANALLI, Antonio (Via Beato Amico 39, Montefano, Province of Macerata, I-62010, IT)
RENZI, Massimiliano (Piazza 18 Settembre 4, Recanati, Province of Macerata, I-62019, IT)
USCI, Rosalino (Via Clementina 10, Jesi, Province of Ancona, I-60035, IT)
| CLAIMS 1 . A sun tracker (1 ), in which at least one solar radiation collecting element (2) is supported by a corresponding device (3) designed to orient it in space in relation to a fixed reference system, is characterized by the fact that said device (3) comprises three rigid members (4,5,6) arranged in sequence and two rotary couplings (7,8) - connecting the rigid members (4,5,6) in pairs - having rotation axes (9,10) angled at 90 degrees to each other; the tracker (1 ) including stepper motors (12) for rotation of said members (4,5,6) about the axes (9,10) of said couplings (7,8); and control means (13) to activate controlled movement of said rigid members (4,5,6). 2. A tracker (1 ), according to claim 1 , characterized by the fact that said one or more solar radiation collection devices (2) each comprise a mirror reflecting incident solar radiation. 3. A tracker (1 ), according to claim 1 , characterized by the fact that the stepper motors (12) include gear motors (14,15) installed to run between the first (4) and second rigid member (5) and between the second (5) and third rigid member (6); the first gear motor (14) having a casing (14c) solidly attached to the second rigid member (5) and a shaft (14a) integrally connected to the first rigid member (4); the second gear motor (15) having a casing (15c) solidly attached to the third rigid member (6) and a shaft (15a) rigidly connected to the second rigid member (5). 4. A tracker (1 ), according to claim 3, characterized by the fact that the shaft (14a) of the first gear motor (14) implements the pin of the first coupling (7); a pair of wings (5s) of said second rigid member (5) supporting free rotation of said shaft (14a), to which corresponding brackets (4s) of the first rigid member (4) are rigidly connected. 5. A tracker (1 ), according to claim 3, characterized by the fact that the shaft (15a) of the second gear motor (15) forms a pin for the second coupling (8), providing cantilever support for the first (4) and second (5) rigid members overall. 6. A tracker (1 ), according to claim 5, characterized by the fact that said shaft (15a) is connected to the second rigid member (5) in a position offset from its centre line. 7. A tracker (1 ), according to claim 1 , characterized by the fact that at least the first (4) and second (5) of said rigid members (4,5,6) are L-shaped plates whose respective wings are partially overlapping (4a, 5a) and are connected by the first (7) of said rotary couplings (7,8), which is integrated into the stepper motors (12). 8. A tracker (1 ), according to claim 6, characterized by the fact that said stepper motors (12) comprise a first gear motor (14) having a fixed shaft (14a) that forms a pin for said first coupling (7), and a casing (14c), attached to said first rigid member (4) , both of which revolve around said fixed shaft (14a). 9. A tracker (1 ), according to claim 7, characterized by the fact that said stepper motors (12) include a second gear motor (15) having a shaft (15a) that forms a pin for said second coupling (8), and a casing (15c), attached to said second rigid member (5), both of which revolve around said shaft (15a) with respect to the third rigid member (6). 10. A tracker (1 ), according to claim 1 , characterized by the fact that the first (4) of said three rigid members (4,5,6) is integral with the solar radiation collection device (2) and has two brackets (4s) at either end; the second (5) of said rigid members (4,5,6) is cross-shaped and its longer element (5e) bears at either end two pins (5p) connected with said brackets (4s), forming together the first rotary coupling (7); the stepper motors (12) comprising a first gear motor (14) with a fixed shaft (14a) integral with the pins (5p), and a casing (14c), attached to the first rigid member (4), both of which rotate around the fixed shaft (14a) of the first gear motor (14). 1 1 . A tracker (1 ), according to claim 9, characterized by the fact that said second coupling (8) comprises connected members (6p,5f) interposed between the second (5) and third (6) rigid member; the stepper motors (12) including a second gear motor (15) having a mobile shaft (15a) integral with the second element (5f) of the cross- shaped member (5), and a casing (15c) attached to said third rigid member (6). 12. A tracker (1 ), according to any of the above-mentioned claims, characterized by the fact that it includes automatic slack recovery devices (16) operatively associated with said stepper motors (12). 13. A tracker (1 ), according to claim 1 1 , characterized by the fact that said automatic slack recovery devices (16) include spiral elastic elements (16m). 14. A battery of modular trackers, realized in line with any of the above-mentioned claims, characterized by the fact that a single set of said control devices (13) enables sequential operation of the trackers (1 ) of a plurality of trackers in the battery (17). |
SUN TRACKER AND BATTERY OF SUN TRACKERS DESCRIPTION
The present invention refers to the construction of sun trackers and, in particular, tracker batteries where a plurality of trackers are combined to realize more complex solar thermal energy plants.
Characteristically sun trackers are endowed with various types of mechanical devices providing support for the sun collection surface and its optical orientation towards the sun during the day.
Despite an adequate performance, large tracker batteries realized according to the known art are penalized by their high mechanical complexity, which results in high construction and maintenance costs and suboptimal medium-long term operating reliability.
The aim of the present invention is to overcome such limitations by providing a tracker that combines high mechanical and operating precision with very simplified construction, thus enabling assembly of reliable, long-life solar collection batteries with high-precision tracking features at low cost.
The technical features of the disclosed invention according to the above-stated aim are set forth in the appended claims. Its advantages will be apparent from the detailed description, made with reference to attached drawings, of an embodiment that is reported by way of example and is not intended to limit the invention, in which:
- figure 1 is a schematic perspective view of the invention;
- figure 2 is a schematic view partially in section, showing a first alternative variant of the invention;
- figure 3 is a view from above of a second variant of the invention;
- figure 4 is a schematic diagram of a solar energy collection plant obtained by combining a plurality of sun trackers implemented according to the disclosed invention.
Figure 1 of the attached drawings shows a sun tracker 1 whose structure essentially comprises a solar radiation collector 2 and a device 3 - to be considered secured to the ground using a known method - supporting collector 2 and providing for its optical orientation depending on the sun's position during the day and season.
The orientation of collector 2 is defined by the configuration assumed at any given time by device 3 as a result of the activation of associated motors 12, and of suitable signals from command and control means, symbolically represented by block 13 in the figures.
Solar radiation collector 2 is described in the embodiment of the invention disclosed herein as a flat-surface mirror suitable for reflecting and focusing incident radiation striking a well-defined spatial location, which may be occupied, for example, by a user defined in the broadest and most generic possible way.
Nonetheless, said solar radiation collector 2 can also have a different design to that represented herein including, for instance, its own device for direct conversion of solar energy to thermal or electrical energy, without departing from the technical scope of the invention.
Device 3 essentially comprises a metal structure formed by three rigid members 4, 5 and 6, arranged in sequence, and by two rotary couplings 7 and 8, connecting members 4, 5 and 6 in pairs, enabling their rotation with respect to one another as well as about two axes 9 and 10, angled at 90 degrees to one another.
More particularly, first rigid member 4 in the embodiment of tracker 1 shown in figure 1 essentially comprises solar radiation collector 2, which bears - on the side opposite the reflecting surface - two flat, parallel brackets 4s set perpendicular to the receiver surface that jut down towards underlying device 3.
Second rigid member 5 is implemented as a U-shaped metal plate whose central portion 5a has two parallel wings 5s on either end, said wings being turned towards brackets 4s of first rigid member 4.
Third rigid member 6 is a sturdy metal beam preferably having an open-shape, rectangular hollow section, delimited by a slim wall 6h that is open on the bottom side of the beam.
The beam, which constitutes said third member 6, supports the first 4 and the second 5 rigid members, and - as clearly shown in figure 1 - can also support respective members 4 and 5 of a plurality of trackers 1 arranged in series and deployed as a battery 17 on the length of the beam.
First rotary coupling 7, which provides for rotation of first rigid member 4 about horizontal axis 9, is realized as a pin passing through wings 5s of second rigid member 5 and connecting rigidly to brackets 4s of first rigid member 4, its free rotation being enabled by support from wings 5a of second rigid member 5.
A first gear motor 14 - of stepper type 12 - is connected through its own casing 14c to second rigid member 5, being attached to the outer side of either one of two brackets 5s of the U-shaped plate.
Gear motor 14 is provided with shaft 14a, which is in fact the pin implementing the first rotary coupling 7 and driving the rotation of first rigid member 4 about axis 9, to change the tilt angle of solar collector 2 with respect to said axis 9.
Second rotary coupling 8 - which connects second 5 and third 6 rigid members - is a vertical shaft 15a that passes, from bottom to top, through the beam constituting third rigid member 6, and connects rigidly to the central portion 5a of the U-shaped plate of second rigid member 5 by means of its own pin.
Shaft 15a - constituting the pin of second coupling 8 - is in fact the shaft of a second gear motor 15, also of stepper type 12.
Second gear motor 15 is provided with casing 15c, which is rigidly attached to the beam constituting third rigid member 6 on the beam side facing the collector 2.
Shaft 15a, which is rigidly connected to central portion 5a of the U-shaped metal plate, offset from the centre line, provides cantilever support for both the first 4 and the second 5 rigid member and drives their rotation about vertical axis 10, to orient solar collector 2 around vertical axis of rotation 10.
The above-described embodiment of tracker 1 is both easy and economical to produce. It is equally easy, fast and economical to assemble and/or maintain a battery 17 of sun trackers 1 collectively sharing third rigid member 6, implemented as a single beam of appropriate length as shown in figures 1 and 4.
The construction simplicity and small size of the various components of the structure of device 3 entail the added benefit of enabling use of gear motors 14 and 15 of limited size and power, thus also reducing general manufacturing costs as well as overall energy consumption by the sun collection plant to which they are associated. Figure 2 shows a second, alternative embodiment of tracker 1 , where the first 4 and the second 5 rigid members are L-shaped plates whose respective wings 4a and 5a are partially superimposed and are connected by first rotary coupling 7, which enables their revolution around horizontal axis 9.
Also in this case first rotary coupling 7 is part of first gear motor 14, of stepper type 12. However in this embodiment first gear motor 14 is deployed so as to be supported by mobile rigid member 4, rather than by fixed rigid member 5, of the pair of members 4 and 5 considered here.
In fact, casing 14c of first gear motor 14 is attached to wing 4a of first rigid member 4, while shaft 14a, constituting the pin of rotary coupling 7, is designed to pass through juxtaposed wings 4a and 5a, finally connecting rigidly to wing 5a of second rigid member 5.
As a result of this configuration, upon activation of first gear motor 14, rigid member 5 prevents rotation of shaft 14a of first gear motor 14, consequently causing rotation of casing 14c around the pin that serves as the centre of rotation. The resulting angular shift of rigid member 4, connected to casing 14c, allows tilting of solar collector 2 about axis of rotation 9, as required at any given time.
A similar arrangement, involving second rotary coupling 8, is illustrated in figure 2. In this configuration casing 15c of second gear motor 15 is rigidly attached to horizontal wing 5a of second member 5, whereas shaft 15a passes through said wing 5a and the juxtaposed central portion 6a of beam 6, and is then rigidly attached to said core 6a.
In exactly the same way as described above for first coupling 7, also for second coupling 8 activation of stepper motors 12 entails rotation of casing 15c and of second member 5 connected to it, and a corresponding shift of solar radiation collector 2, in this case about vertical axis 10.
In the aforesaid embodiment the structural rigidity and resistance properties of tracker 1 are mainly provided by gear motors 14 and 15, resulting in further construction simplification and cost reduction.
A third embodiment of tracker 1 is shown in figure 3, where the terms and symbols used previously still apply. In this embodiment, first rigid member 4 of device 3, integral with collector 2, has two parallel brackets 4s.
Second rigid member 5 has a cross shape, with two solid, elongated elements 5e and 5f set at right angles to each other.
Element 5e bears on either end fixed cylindrical pins 5p that provide support for, and enable free rotation of corresponding complementary ends of brackets 4s of first rigid member 4. Fixed pins 5p and brackets 4s make up first coupling 7, which allows rotation of solar radiation collector 2 about axis 9. The rotation is driven by first gear motor 14, whose casing 14c, also in this configuration, is attached to first rigid member 4 and whose shaft 14a is connected rigidly to first elongated element 5e of cross-shaped member 5, imparting motion to casing 14c with respect to shaft 14a. The second elongated element 5f of cross-shaped member 5 is supported at either end by pins 6p perpendicular to axis 9, which in turn are supported by a pair of vertical arms 6b jutting from a horizontal beam 6t. Beam 6t, arms 6b and pins 6p constitute third rigid member 6 of device 3.
Second rotary coupling 8 comprises said pins 6p and corresponding and complementary cylindrical housings 5f in arms 6b; pin 6p and housing 5f enabling vertical tilt of element 5e, i.e. rotation about horizontal axis 10, orthogonal to axis 9.
This rotation is also driven by second gear motor 15, whose casing 15c is integral with one of the arms 6b of third rigid member 6, and whose shaft 15a rotates solidly with second element 5f of cross-shaped member 5.
With reference to the implementation of stepper gear motors, it is preferable to mount
48-step-per-revolution motors and gear motors with a high reduction ratio, e.g. 100:1 , which combined make it possible to achieve an angular resolution in the order of
0.075°.
All the described embodiments of tracker 1 are fitted with automatic slack recovery means (indicated as 16 in figure 3), which also meet practical needs, to take up the slack that normally arises between the moving parts of device 3. Automatic slack recovery means 16 may comprise for instance spiral elastic elements 16m fitted as springs that enable automatic slack recovery.
This feature is important and useful, since it keeps the magnitude of the aforesaid angular resolution constant, despite the greater operating slack typical of commercial gear motors. A further advantage of the disclosed invention is that it enables use of stepper motors to drive couplings 7 and 8, said motors being able to be managed by simple command means 13 (rather than, for instance, feedback controls), thus achieving enormous simplification of the control of the configuration of device 3 without losing precision regulation of sun radiation collector 2.
As mentioned above, tracker 1 realised according to the disclosed invention is also particularly suitable for construction of large batteries 17 of solar collectors 2, to realize sun collection plants of various sizes and power that are scalable, reliable, as well as relatively easy to control.
The invention thus conceived is clearly highly suitable for industrial applications; it can also be modified to create countless variations, all lying within the scope of the invention concept; moreover, all components can be replaced by technically equivalent elements.