TRACKING DEVICE

Abstract

The invention relates to a passive tracking device for tracking the position of the sun, which comprises a hollow parallelepiped casing through which the solar radiation entering through a first lens located at the upper end of the parallelepiped casing passes towards a discriminating reflector arranged at the lower end of the same casing; the tracking device redirects as much incoming radiation as possible towards side chambers for absorbing radiation, heating a working fluid contained in the side chamber; producing a volumetric expansion in the working fluid that, communicating with shafts for the rotation of the tracking device, allows the orientation with the normal/perpendicular position with respect to the position of the sun, and to guide the alignment direction of other tracking devices for collecting energy in devices for collecting photovoltaic and/or thermal energy that are mechanically connected to the tracking device.

Claims

1. A solar-position tracking device comprises a hollow parallelepiped housing (14) and a primary lens (12) at the upper end of the housing (14) to concentrate the incoming solar radiation near the lower end of the same housing (14). It is characterised by the fact that the hollow parallelepiped housing (14) also comprises a discriminating reflector (18) arranged at the lower end of the housing (14) to reflect the incoming concentrated solar radiation to at least one radiation-absorbing side chamber (14) when the parallelepiped housing (14) is aligned and/or misaligned with the sun's position.

2. Device as per claim 1, characterised by the fact that the parallelepiped casing (14) has the shape of the inverted frusto-conical parallelepiped type.

3. Device as per claim 2, characterised by the fact that the parallelepiped housing (14) comprises a multitude of curved-concave reflective side surfaces (16) to reflect concentrated solar radiation to corresponding radiation-absorbing side chambers (17).

4. Device as per claim 3, characterised by the fact that the radiation-absorbing side chambers (17) have a closed hollow cylindrical type shape arranged parallel to and in proximity to a respective arched, reflective, inclined side surface (16).

5. Device as per claim 4, characterised by the fact that the radiation-absorbing side chamber (17) is made of a transparent material that allows the solar radiation spectrum to pass through and prevents the emission of lower frequency wavelengths of radiation generated by the internal heat to provide a greenhouse effect inside.

6. Device as per claim 4, characterised by the fact that a radiation-selective absorber (41) is placed inside the side chamber (17) which absorbs radiation.

7. Device as per claim 3, characterised by the fact that at least two opposing side surfaces (16) have a lower section adjacent to the lower end with a Fresnel-type profile and an upper section adjacent to the upper end has a linear lens type side lens (13).

8. Device as per claim 7, characterised by the fact that the side lens (13) concentrates the incoming solar radiation on the absorbing chamber (17) which is located near the side surface (16) opposite the side lens (13).

9. Tracking device as per claim 2, characterised by the fact that at least two opposing side surfaces (16) have a lower section adjacent to the lower end with a Fresnel-type profile and an anchor centred on the tracking device's centre of gravity (11) where actuator pistons (21) are arranged and linked to the rotary axes of the tracking device (11).

10. Device as per claim 1, characterised by the fact that the primary concentrator lens (12) is a Fresnel lens with a flat upper profile and Fresnel lower profile to concentrate the solar radiation on a focal point or line close to the discriminating reflector (18).

11. Device as per claim 1, characterised by the fact that the discriminating reflector (18) comprises at least two arched reflective surfaces (51) with an inverted V-shaped cross-section to project the concentrated incoming solar radiation onto the radiation-absorbing side chambers (17).

12. Tracking device as per claim 11, characterised by the fact that the discriminating reflector (18) is an aspherical lens, a parabolic revolving mirror, a Fresnel zone plate or similar.

13. Device as per claim 11, characterised by the fact that the reflective surface (51) of the discriminating reflector (18) has a flat arched cross-section of the concave plane, parabolic plane, elliptical plane or similar type.

14. Device as per claim 11, characterised by the fact that the discriminating reflector (18) comprises a through-slot (52) below which is positioned a lower receiver (71) for collecting radiation adapted to provide thermal energy and/or electrical energy.

15. Tracking device as per claim 9, characterised by the fact that the actuator piston (21) comprises a fixing and rotating tool to allow at least one rotational movement of the tracking device (11).

16. Device as per claim 15, characterised by the fact that the actuator piston (21) is connected to the corresponding radiation-absorbing side chamber (17) by means of flexible tubes in order to absorb the pressure increase produced inside the radiation-absorbing side chamber (17).

17. Device according to claim 9, characterised by the fact that the actuator piston (21) comprises flexible membranes or diaphragms (31) arranged at opposite ends of the actuator piston (21) to exert a thrust by folding or unfolding the same membranes or diaphragms (31).

18. Device according to claim 9, characterised by the fact that the actuator piston (21) is arranged on the rotary axis of the tracking device (11) to provide a rotation of the tracking device (11) according to the east/west and/or north/south movement in accordance with the sun's position.

19. Device as per claim 18, characterised by the fact that the actuator piston (21) respectively receives the volumetric expansion produced within the opposing radiation-absorbing side chambers (17), east/west and/or north/south, at the ends of the same actuator piston of the tracking device (11).

Description

BRIEF DESCRIPTION OF FIGURES

[0028] A more detailed explanation is given in the following description which is based on the attached figures:

[0029] FIG. 1 shows a perspective view of a cross-section of a passive solar-position tracking device using concentrated solar radiation;

[0030] FIG. 2 shows a rear perspective view of the passive solar-position tracking device using concentrated solar radiation;

[0031] FIG. 3 shows an overhead view of an actuator piston of the passive solar-tracking device using concentrated solar radiation;

[0032] FIG. 4 shows an overhead view of a radiation-absorbing side chamber of the passive solar tracking device using concentrated solar radiation;

[0033] FIG. 5 shows a plan view of a discriminating reflector of the passive solar-position tracking device using concentrated solar radiation;

[0034] FIG. 6 shows a schematic overhead view of the passive solar-position tracking device using concentrated solar radiation in an on-axis condition and in an off-axis condition;

[0035] FIG. 7 shows a schematic overhead view of the through-slot of the discriminating reflector of the solar-position tracking device using concentrated solar radiation in the on-axis and off-axis condition;

[0036] FIG. 8 shows a perspective view of some alternatives of the discriminating reflector without and with a through-slot;

[0037] FIG. 9 shows a perspective view of additional alternatives of the discriminating reflector without and with a through-slot;

[0038] FIG. 10 shows a perspective view of additional alternatives of the discriminating reflector with the absence of a non-active reflective surface;

[0039] FIG. 11 shows an alternative overhead view of a radiation-absorbing side chamber of the passive solar-position tracking device using concentrated solar radiation;

[0040] FIG. 12 shows a frontal perspective view of tracking devices arranged in a horizontal frame according to an east-west axis to guide the positioning of photovoltaic- and/or thermal-energy harnessing devices in real time;

[0041] FIG. 13 shows a frontal perspective view of tracking devices arranged in a horizontal frame along an east-west axis to guide the positioning of photovoltaic- and/or thermal-energy harnessing devices in real time;

[0042] FIG. 14 shows a frontal perspective view of tracking devices arranged in a vertical frame to guide the positioning of photovoltaic- and/or thermal-energy harnessing devices in real time; and

[0043] FIG. 15 shows a rear perspective view of tracking devices arranged in a vertical frame to guide the positioning of photovoltaic- and/or thermal-energy harnessing devices in real time.

DESCRIPTION

[0044] With reference to FIGS. 1, 2 and 3, in which a concentrated solar thermal-energy tracking device 11 is shown to target solar radiation at a predetermined location of the device and guide the alignment direction of a Photovoltaic- and/or thermal-energy arrangement.

[0045] The passive solar-position tracking device 11 is configured to redirect the maximum incoming radiation in a fast and precise manner to radiation-absorbing side chambers 17 in order to heat working fluid contained in the same side chamber 17 and thus produce a volumetric expansion in the working fluid that is transferred to some rotary axes of the tracking device 11 that allows automatic orientation, in real time, of the tracking device 11 with the normal/perpendicular position with respect to the position of the sun, and to guide the alignment direction of other tracking devices so that the energy is exploited in a highly concentrated way by photovoltaic- and/or thermal-energy harvesting devices mechanically connected to the passive tracking device 11 tractor and position marker, thereby obtaining the harnessing of the maximum solar radiation in a very concentrated way.

[0046] The passive solar-position tracking device 11 and solar concentrator comprises a hollow parallelepiped housing 14 which is penetrated by the incoming solar radiation through the primary concentrator lens 12 located at the upper end of the parallelepiped housing 14 into a discriminating reflector 18 positioned at the lower end of the same housing 14, when the sun's position is close to the normal/perpendicular position of the tracking device 11.

[0047] The parallelepiped casing 14 has an inverted frusto-conical parallelepiped type shape. It comprises a multitude of arched reflective side surfaces 16 of the curved-concave reflective side surface type to reflect the solar radiation onto the absorbing side chambers when the sun's position is far from perfect alignment with the normal/perpendicular position of the tracking device 11.

[0048] The tracking device 11 is mechanically coupled to an actuator piston 21 positioned near the centre of gravity of the parallelepiped housing 14 comprising fixed and rotatable tools to allow a rotational movement without displacement of the tracking device 11 from an initial position corresponding to sunrise and to an end position relative to sunset, and vice versa.

[0049] At least two opposite side surfaces 16 have a lower section adjacent to the lower end of the parallelepiped housing 14 with a Fresnel-type profile and an upper section adjacent to the upper end of the same parallelepiped housing 14 which has a lateral lens 13 of the linear lens type and which makes the incoming solar radiation linearly converge on the radiation-absorbing side chamber 17 opposite the corresponding lateral lens 13, when the sun is in a low position on the horizon at sunrise and sunset.

[0050] The lateral surfaces 16 are arranged facing respectively different opposite cardinal points, so that a primary surface 16 is positioned towards the eastern cardinal point and a second surface 16 is positioned towards the western cardinal point.

[0051] At least two opposing side surfaces 16 have a lower portion adjacent to the lower end with a Fresnel-type profile and an upper portion 15 adjacent to the upper end of the parallelepiped housing 14 where the actuator piston 21 is located. The side surfaces 16 are positioned facing opposite cardinal points respectively so that a third surface 16 is positioned towards the northern cardinal point and a fourth surface 16 is positioned towards the southern cardinal point.

[0052] The frusto-conical parallelepiped casing 14 comprises the primary lens 12 concentrator of the Fresnel-lens type, mechanically coupled to the upper end of the parallelepiped housing 14 to concentrate the solar radiation on a focal point located in proximity to or on the discriminating reflector 18 when the sun's position is close to the normal/perpendicular position of the primary lens.

[0053] The primary concentrator lens 12 has a flat upper and lower Fresnel profile that concentrates the solar radiation on the focal point of the discriminating reflector 18 when the sun's incident rays are perpendicular to the primary lens 12; on-axis condition.

[0054] With reference to FIGS. 5 to 10, the discriminating reflector 18 comprises at least two reflective surfaces 51, having, respectively, an arched, curved-concave or similar cross-section in an inverted V-shape that projects the concentrated solar radiation towards the corresponding radiation-absorbing side chamber 17.

[0055] The apex of the inverted arched V corresponds to the focal point of the primary concentrator 12 lens, if the sun's position is normal/perpendicular to the primary concentrator 12 lens. The reflective surfaces 51 of the discriminating reflector 18 respectively have an arched planar cross-section of the concave plane, parabolic plane, elliptical plane or similar.

[0056] The discriminating reflector 18 is an aspherical lens (not a Fresnel lens), a parabolic revolving mirror, a Fresnel zone plate or similar.

[0057] The solar-position tracking device 11 further comprises at least two radiation-absorbing side chambers 17 facing two by two which contain the working fluid of the liquid, gas or similar type. Therefore, depending on the variation in relative pressure inside the radiation-absorbing side chambers 17, the positioning of the tracking device 11 is automatically changed.

[0058] The pressure increase inside the radiation-absorbing side chambers 17 is transmitted through flexible tubes from the corresponding radiation-absorbing side chamber 17 to the actuator piston 21 so that it guides the rotational movement of the tracking device 11 in coordination with the position of the sun in real time.

[0059] In this way, a perfect synchronisation of the rotational movement east-west or north-south of the tracking device 11 is achieved so that it automatically orients itself according to the position of the sun.

[0060] The pressure of the absorbing side chamber on the western side 17 is inked to the eastern side of the east-west actuator piston, and with the increase of pressure in the eastern side of the actuator piston 21, it pushes the east-west actuator piston 21 to the west so that a rotating component of the actuator piston 21 rotates clockwise, causing the tracking device 11 to turn to the east.

[0061] Therefore, the pressure variation on the eastern or western side of the actuator piston 21 provides real-time tracking of the sun's position along the east-west axis.

[0062] Similarly, the same tracking mechanism occurs in the north-south seasonal movement, intervening in the north and south radiation-absorbing side chambers and the north-south actuator piston 21 in exactly the same way as the east-west actuator piston 21 described for the daily east-west movement.

[0063] With reference to FIGS. 3 and 11, the radiation-absorbing side chambers 17 are closed hollow bodies with an elongated tubular structure of the cylinder type which include pressure communication lines connected between the radiation-absorbing side chamber 17 and the corresponding actuator piston 21 comprising mechanical devices for converting a pressure increase into a rotary movement.

[0064] The radiation-absorbing side chamber 17 is mechanically coupled in a suspended and parallel manner to the corresponding arched reflective inclined side surface 14. It is located between the reflective inclined side surface 17 and the symmetrical axis of the frusto-conical parallelepiped housing.

[0065] In turn, the working fluid is heated to high temperatures in order to increase the internal pressure of the radiation-absorbing side chamber 17 itself, by direct solar radiation and/or radiation reflected by the internal surfaces of the parallelepiped frusto-conical housing.

[0066] Consequently, the arched reflective inclined side surfaces 16 of the frusto-conical parallelepiped housing 14 reflect the received solar radiation towards the corresponding radiation-absorbing side chamber 17 arranged parallel to and at a predetermined distance from the arched reflective inclined side surface 16 to reflect the radiation. This impacts on the respective absorbing side chamber 17 causing it to heat up, and consequently causes a volumetric expansion by pressure that is transmitted towards the rotary axis of the tracking device 11, providing it with a rotational movement in real time, a function of the internal pressure of the radiation-absorbing side chambers 17 as they search for the most appropriate orientation according to the position of the sun.

[0067] The lateral tubular radiation-absorbing chambers are arranged in a cross on the east-west and north-south axes according to the cardinal points, and may be within the same tracking device 11 or in two tracking devices 11 where a first tracking device 11 performs the east-west movement and a second tracking device 11 performs the north-south movement of tracking the sun's position.

[0068] The radiation-absorbing side chamber 17 is made of glass or another transparent material adapted to contain the working fluid.

[0069] A thin concentric annular tube 41 is provided inside the radiation absorbing side chamber 1. The tube 41 is of a type of material such as metal which is darkened so that incoming solar radiation passes through the transparent wall of the side chamber 17 and is absorbed by the metal tube 41 which directly heats the working fluid.

[0070] The arrangement with glass or another transparent material may distinguish the wavelengths of solar radiation in order to provide a greenhouse effect and thus limit indoor-energy losses due to radiation.

[0071] Alternatively, the thin tube 41 features an oblique hole 42 arranged at the bottom end of the tube 41 facing the discriminating reflector 18 so that the radiation reflected by the same discriminating reflector 18 enters the thin tube 41 through the oblique hole 42 and thus produces heating in the inner part of the thin tube 41.

[0072] The thin tube 41 has an uncoated lower section with relatively high reflectivity, so that the solar radiation incident on the lower section is additionally reflected in a more scattered manner to an upper section of the thin tube 14 in order to increase the diffusion of the solar radiation and produce a more homogeneous heating.

[0073] With reference now to FIGS. 6 and 7, where the solar-position tracking device 11 is shown with different entry angles of direct solar radiation and details how the precise differentiation of the concentrated incoming solar radiation is produced in an on-axis condition and, therefore, the concentrated solar radiation falls on the focal point, the vertex of the discriminating reflector 18, reflecting the solar radiation on two radiation-absorbing side chambers 17 located in accordance with the eastern and western cardinal points respectively, an equal portion of the solar radiation is directed into either of the radiation-absorbing side chambers 17 positioned opposite one another.

[0074] However, the tracking device 11 may be misaligned with the sun in an off-axis condition such as in FIG. 6. Here, a misalignment is shown with an angle of 5° between the vertical and the position of the sun and, therefore, the focus of the concentrated incoming solar radiation is located on one of the reflecting surfaces 51 of the discriminating reflector 18, so that the aforementioned reflecting surface 51 directs all the concentrated incoming solar radiation to the corresponding radiation-absorbing side chamber 17. For example, the western radiation-absorbing side chamber 17 is operational and the eastern radiation-absorbing side chamber 17 is idle.

[0075] In short, as the sun moves, the radiation reflected to an absorbing side chamber 17 increases and the reflected radiation received by the opposite radiation-absorbing side chamber 17 decreases, as a result of the change in temperature of the radiation-absorbing side chambers 17. The change in the working fluid temperature takes place with very small changes in the position of the sun, which allows fast, accurate and powerful real-time tracking of the sun's position.

[0076] Alternatively, the discriminating reflector 18 has a through-slot 52 that allows some of the solar radiation to pass through the same slot 52 so that the remainder of the incoming solar radiation is directed into the corresponding absorbing side chamber 17 based on the sun's position.

[0077] Depending on the physical dimensions of the through-slot 52 and depending on the dimensions of the focal point or line generated by the primary upper lens 12, it is perfectly possible to regulate what percentage of energy is directed towards each radiation-absorbing side chamber 17 or penetrates the through-slot 52, thus regulating the behaviour and evolution of the rotational movement of the tracking device 11 during movement when tracking the sun's position.

[0078] The through-slot 52 takes on different shapes, e.g. an elongated shape arranged so that its smaller dimension, its width, is crossed by the focal point generated by the primary lens 12.

[0079] Below the through-slot 52, a lower receiver 71 of the lower thermal receiver type is provided to produce thermal energy when the tracking device 11 is in normal/perpendicular position with respect to the axis position; e.g. a liquid fluid circulating inside the lower thermal receiver 71 is heated to heat water for domestic water or another purpose.

[0080] Alternatively, a lower photovoltaic cell is positioned below the through-slot 52 to produce electrical energy.

[0081] The lower receiving radiation collector 71 receives the solar radiation that the discriminating reflector 18 does not reflect back into the absorbing side chambers 17.

[0082] With reference now to FIGS. 9 and 10, the discriminating reflector 18 comprises four reflective surfaces 51 in the shape of an inverted arched V positioned in a cross, which projects the concentrated incoming solar radiation into one of the four radiation-absorbing side chambers 17 arranged in a cross within the parallelepiped housing 14 of a single tracking device 11, which can be rotated along the two east-west and north-south axes.

[0083] Therefore, the discriminating reflector 18 is divided into at least four curved reflecting surfaces 51 to direct the concentrated solar radiation to one of the four corresponding radiation-absorbing side chambers 17 in order to produce the expansion of the working fluid so that the pressure within two side chambers 17 increases and is transmitted to the corresponding ends of the actuating pistons 21 to trigger rotation along the two east-west and north-south axes.

[0084] The rotation along an axis occurs in either absorbing side chamber as a result of an increase in pressure and/or volumetric expansion of the working fluid i.e. in the east or west chamber, and in the north or south chamber.

[0085] The tracking device 11 is adapted to include a mechanism that provides a return force contrary to the rotational movement provided by an absorbing side chamber; the mechanism is a spring, counterweight, pressurised cylinder or similar type of component. Therefore, the discriminating reflector 18 exhibits the absence of a non-active reflective surface 111. In other words, the discriminating reflector 18 does not physically extend over the entire area of the lower end of the parallelepiped housing, which is a non-active part thereof.

[0086] Consequently, on the part of the discriminating reflector 18 that does not have a reflecting surface 111, a lower radiation collector with larger dimensions 71 can be arranged to transform the concentrated solar radiation into thermal or electrical energy for all the angles that correspond to this area.

[0087] With reference to FIGS. 12, 13, 14 and 15, a frontal perspective view shows the solar-position tracking device 11 that tracks the solar concentration which guides, in real time, the orientation of a multitude of devices for the use of photovoltaic and/or thermal energy. FIG. 13 shows a posterior perspective view of the same device and configuration.

[0088] FIGS. 12 and 13 show the directions according to the cardinal points, which assume that the system is mounted in the northern hemisphere. For use in the southern hemisphere, the assembly would be rotated 180° to point north.

[0089] A rigid vertical frame 141 is fixed to the floor and fitted with swivel joints that allow the assembly of a multitude of swivel frames 142 that rotate around the east-west axis.

[0090] Each 141 rotation frame is fitted with swivel joints that enable the installation of a number of tracking devices 11 which are traction units that guide the movement of tracking components for the use of photovoltaic and/or thermal energy.

[0091] A rigid bar mechanically couples several energy-collecting tracking components with the tracking device 11 so that they rotate simultaneously. In this way, the rotation of the tracking device 11 is automatically transferred to the energy-collecting components.

[0092] The operation of the two-axis tracking device 11 is similar, with the exception that it is connected to two rotating systems. The first axis causes a movement in the east-west direction with respect to the swivel frame, as in single-axis tractor units, and the second axis provides a rotation of the swivel frame in the north-south direction. All swivel frames are connected by mechanical joints that provide a rotation on both axes to the energy-collecting components.

[0093] FIG. 13 shows a rear perspective view of the solar-concentration tracking device 11, which guides the orientation of the photovoltaic- and/or thermal-energy arrangement where at least one concentration tracking device 11 is combined with a multitude of energy-collecting components arranged on a rotatable frame in such a way as to allow the arrangement to rotate in the direction of elevation so that the optical axes of the energy-harvesting components move closer or further away from the zenith.

[0094] The swivel frame is mounted on a fixed frame 141 such as a single post or pedestal, in such a way as to enable the swivel frame 142 to be rotated in the azimuth direction. A second mechanical tool is provided to cause this rotation.

[0095] Communication between the primary actuator piston 21 and the rotating component can be carried out by means of a cable generating a longitudinal rack on the primary actuator piston 21 that engages with a toothed circular pinion fitted to the rotating component.

[0096] With reference to FIG. 3, the flexible elastomer membranes or diaphragms 31 are arranged at the opposite ends of the actuator piston 21 in such a way that the pressure thrust on the actuator piston 21 occurs in a smooth, progressive and precise manner by folding and unfolding the membranes 31 and triggering the friction of the actuator piston 21 on the piston cylinder liner.

[0097] The concentrator tracking device 11 is arranged according to the four cardinal points that divide the horizon into equal parts, so that each side surface 16 of the parallelepiped 14 housing looks directly into a cardinal point so that the side surfaces 16 of the parallelepiped 14 housing can be identified as the north side surface, east side surface, south side surface and west side surface.

[0098] Consequently, a radiation absorbing side chamber 17 is respectively located close to the centre of the east, west, north and south inclined, arched side surface 14.