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DESCRIPTION TEXT Field of the invention

The present invention refers to a solar collector comprising :

at least one collector element including a transparent portion and a reflecting portion, said at least one collector element, being deformable from a substantially flat shape to a substantially tubular shape

support means arranged for receiving a solar absorber device, and

- at least one shaping element positionable at each opposite end of said at least one collector element to maintain said substantially tubular shape.

Description of the prior art

Various types of devices exploiting different technologies are known in the field of the conversion of solar energy into thermal or electric energy.

In particular, one of such types is that of the so-called concentration systems, which comprises devices based on the non-imaging optics laws and exploiting reflecting surfaces capable of concentrating energy in a predetermined region of the space, for example corresponding to a focal line of a reflector having a parabolic or generally curved profile. Such devices have several advantageous features, firstly the wide range of structures that can be used for making them. This is particularly important when a foldable or anyway collapsible solar collector is required. Such solar collectors are illustrated in a plurality of documents such as, for example, US 4,051,834. This document illustrates a transportable solar collector having a linear absorber whereon the light radiation energy coming from the sun is concentrated and having a polymeric material structure that can be inflated and deflated to allow a quick deployment and collapse in order to transport it from one place to another.

A device which is also collapsible but having a completely different structure is shown in WO 2004/065861 Al . This document, which discloses a portable concentration solar collector comprising a plurality of panels and foldable structures that can be assembled to form a closed container having the shape of a parabolic reflector and wherein liquid canisters that are to be heated can be inserted.

However, the devices previously described have several drawbacks. In particular the solar collector described in US 4,051,834 requires, due to its inflatable structure, compressors and/or pressurised gas cylinders for the deployment thereof, which renders objectively disadvantageous the use of such devices in situations wherein the least possible encumbrance is required, e.g. in the field of camping equipment.

The collector described in WO 2004/065861 Al has the undisputable disadvantage of requiring a complete assembling of the structure, which is susceptible of lengthening in a considerable manner the deployment time in case an array of collectors is to be installed.

Object of the invention

The object of the present invention is that of overcoming the prior art drawbacks. In particular, the object of the present invention is to provide a solar collector single or otherwise composed that can be transported easily and deployed on the field in a manner that is simple, quick and without requiring assembling or further equipment.

Summary of the invention The object of the present invention is attained by a solar collector having the features forming the subject of the claims that follow, which form an integral part of the technical disclosure herein provided in relation to the invention.

In particular, the object is attained by a solar collector having the features listed at the beginning of the present description and wherein, furthermore, the at least one shaping element is integral with said at least one collector element and is foldable towards the interior of the at least one collector element when said collector element takes the essentially tubular shape.

Brief description of the drawings

The invention will now be described with reference to the attached drawings, provided purely by way of non-limiting example, wherein:

figure 1 is a perspective view of a solar collector according to the present invention,

- figure 2 is a perspective view of a component of the solar collector of figure 1, together with a solar absorber device,

- figure 3 is a perspective view of the component of figure 2 but illustrating a different configuration, - figure 4 is an enlarged view according to the arrow IV of figure 1,

- figure 5 is a view corresponding to figure 4 but illustrating a possible variant,

- figure 6 is composed by six portions indicated with the letters A, B, C, D, E, F illustrating a deployment sequence of the solar collector herein disclosed and of a single collector element, wherein figure 6F illustrates also a solar absorber coupled with the solar collector of the present invention,

- figure 7 is a perspective view of a further embodiment of a solar absorber device coupled with the solar collector of the present invention,

- figure 8 is a view according to the arrow VIII of figure 5,

- figure 9 is a perspective view corresponding to figure 6F, but related to the solar absorber of figure 7,

- figure 10 illustrates a second embodiment of a solar collector according to the present invention,

- figures 11 to 13 schematically illustrate different moments of a deployment sequence of the solar collector of figure 10, wherein figure 12 is a view according to the arrow XII of figure 11,

- figures 14 illustrates a variant of the solar collector of figure 1,

- figure 15 illustrates a variant of the solar collector of figure 10,

- figure 16 illustrates a further variant of the solar collector of figure 1 in a first configuration, - figure 17 corresponds to figure 16 but refers to a second configuration and

- figure 18 is a perspective view according to the line XVIII of figure 17.

Detailed description of the invention

A solar collector according to the present invention is indicated with 1 in figure 1. The solar collector 1 comprises one or more collector elements 2, each made of transparent polymeric material. Each collector element 2 is preferably made of a pair of sheets of polymeric material 2A, 2B joined along the junction lines 3 that define the junction strips 3A. Each collector element 2 is deformable and includes a transparent portion 4, associated to the sheet 2A, and an internally reflecting portion 6, associated to the sheet 2B and preferably made of a sheet or a foil of reflecting material positioned inside each collector element 2 on the polymeric material sheet 2B associated to the portion 6, so as to confer light reflection property thereto.

Alternatively it is possible to deposit a layer of reflecting material on the sheet associated to the internally reflecting portion 6.

With reference to figures 1 to 3, support means adapted to receive a solar absorber device 8 are fixed to the transparent portion 4. Said support means comprise a sheath 10 having a hollow section defining a channel 12 wherein the solar absorber device 8 can be inserted. The sheath 10 is fixed to the sheet 2A associated to the transparent portion 4 by a deformable longitudinal strip 14 and is made, as the latter, of polymeric transparent material.

Each collector element 2 further comprises, at opposite ends thereof, shaping elements including a first and a second folding flap 16, 18 integral therewith. At each opposite end there is then located a pair of flaps comprising a flap 16 and a flap 18.

Each flap 16, 18 is configured as a longitudinal extension, respectively, of the polymeric material sheets forming the transparent portion 4 and the internally reflecting portion 6 and it is substantially almond-shaped. In the present description, by the term "almond-shaped" it is meant to define a geometrical figure whose edges are two curves incident in two distinct points at which they define respective cusps, and having facing concavities.

Due to this, each flap 16, 18 comprises two respective cusp-like ends 16A, 18A (figure 3), a respective free edge 16B, 18B and is articulated to the corresponding portion 4 or 6 along a respective folding line 16C, 18C symmetrical with respect to the corresponding free edge with reference to an axis passing through said cusp-like ends 16A, 18A.

The shape of each flap is thus defined by the cusp-like ends 16A, 18A, by the free edges 16B, 18B and by the folding lines 16C, 18C.

Each flap 16, 18 comprises a rectangular opening 20, 21; the openings 20 and 21 are identical to each other, but they have different positions with respect to each flap 16, 18. In particular the opening 20 is located near the folding line 16C, while opening 21 is located near the free edge 18C.

Each collector element 2 can be connected to an adjacent collector element by means of the connection between respective junction strips 3A.

By way of example and with reference to figures 4,

5, the strips 3A can be connected by means of buttons 22 fitted in buttonholes 24 or by snap buttons 26.

In advantageous embodiments, the use of VELCRO© or whatever equivalent connection means can be envisaged.

The solar absorber 8, which can be usable together with the solar collector 1 is herein illustrated in two different embodiments. The first embodiment is shown in figure 6F: the solar absorber 8 includes a support profile 30 whereon two arrays of photovoltaic cells 32 are fixed on opposite parts thereof and connected to each other by means of electrical connections 34. Alternatively, the solar absorber device can include a single array of photovoltaic cells.

A second variant of the solar absorber device is shown in figures 7, 8, 9.

In this embodiment the solar absorber 8 comprises a support profile 36 having a substantially "I-shaped" section comprising two end channels 38, 40 and a central flat member 42. Channels 38, 40 are susceptible of containing water or other fluid, while the central flat member 42 carries two arrays of photovoltaic cells 44 fixed on opposite sides thereof and connected by means of electrical connection 46.

Alternatively the solar absorber device may carry a single array of photovoltaic cells.

The solar collector 1 operates as follows.

Each collector element 2 is deformable from a substantially flat shape, corresponding to a collapsed configuration, to a substantially tubular shape, corresponding to a deployed configuration. Figures 6A, B, C, D, E, F illustrate a deployment sequence of the solar collector 1. Each figure 6C to 6E comprises a broken perspective view of part of solar collector 1 or of a single collector element and a corresponding section taken along respective traces C-C, D-D, E-E.

In figure 6A the solar collector 1 is shown in a collapsed and folded configuration. In this configuration, each collector element 2 is substantially flattened and the internally reflecting portion 6 and the transparent portion 4 are in a minimum distance condition, separated only by the sheath 10 located therebetween.

The sheath 10 can take whatever orientation inside collector element 2 due to the deformability of the longitudinal strip 14. In particular it can take such an orientation that it complies with the flattening of collector element 2.

The collapsed collector elements 2 are disposed in a stacked configuration by means of a substantially "U- shaped" folding of the respective junction strips 3A

In order to begin the deployment of the solar collector 1 it is necessary to bring the collector elements 2 from the stacked configuration of figure 6A to a partially deployed configuration shown in figure 6B. In such configuration the collector elements 2 are placed side by side, but each collector element is still in a collapsed configuration, identical to what shown in figure 6A.

With reference to figure 6C, the deployment of each collector element 2 occurs by exerting a transversal force T on the longitudinal sides thereof, particularly on the junction strips 3A.

The application of the force T on the collector elements 2 causes an outward buckling of the transparent portion 4 and of the internal reflecting portion 6 such that each collector element 2 assumes a pseudo-tubular shape with a substantially almond-shaped section (figure 6D) . In the present description "external" is meant to indicate the spatial region which is not comprised between the portions 4 and 6 of the collector element 2. It follows that "internal" is meant to indicate the spatial region which is comprised between the portions 4 and 6, i.e. between the polymeric sheets of which . each collector element 2 is made.

Moreover, as it can be however deduced from the previous description, it is assumed as longitudinal direction any direction parallel to the development direction of the junction lines 3 (and similarly of the sheath 10) and generally parallel to the portions 4, 6, whatever their configuration (either flattened or buckled) .

Moreover it is pointed out that the sheath 10 spontaneously shifts towards a position similar to that shown in figures 1 to 3, thanks to the flexibility of the longitudinal strip 14.

With reference to figure 6E, by carrying on with the application of the force T on each collector 2, the latter takes a tubular shape which is per se unstable, as the stability thereof is compromised by the elastic return of the portions 4, 6 which tend to return to a configuration substantially similar to that shown in figure 6C .

When the collector element 2 takes the tubular shape shown in figure 6E, in order for such shape to be maintained, it is necessary to sequentially fold the flaps 18, 16 towards the interior of the collector element 2. For instance in the figures the flap 18 is folded in before flap 16, but it is possible to invert the order with a similar result.

The folding occurs along the respective folding lines 16A and 18A and it has an amplitude substantially equal to that of a right angle.

It is clear that, having the folding lines 16A and 18A a curvilinear development, following the folding each flap will assume a shape which is substantially buckled towards the inside of the collector element 2. In such manner, each of the flaps 16, 18 has a stiffness which is able to counteract the elastic return effect of the portions 4, 6, which in this way allows to maintain the tubular shape of the collector element 2.

Moreover, as a further consequence of the folding, the openings 20 and 21, thanks to the arrangement thereof previously described, are aligned so as to form a single opening.

With reference to figure 6F, when the deployment operations of each collector element 2 are completed, it is possible to insert a solar absorber device 8. in each of the channels 12. To this end, the absorber 8 is at first inserted through the apertures 20 and 21 that are aligned when the flaps 16, 18 are folded as described, and thereafter in the channel 12. It is to be noted that the apertures 20 and 21 support the ends of the solar absorber 8, thereby guaranteeing the positioning of the sheath 10 with respect thereto.

Alternatively it is possible to invert the sequence of the operations shown in figures 6E and 6F with the same result.

The collector 1 is then set on a supporting structure or on the ground, so that the portion 6 is in contact therewith. When the solar radiation hits the transparent portions 4 of the solar collector 1, it is refracted and directed towards the internally reflecting portion 6 which, in turn, concentrates a significant amount of the reflected rays onto the solar absorber device 8. In such a way, in case the solar absorber device 8 of figure 6F is used, it is possible to convert the energy associated to the solar radiation into electricity, which may be locally exploited thanks to the facility offered by the electrical connections 34.

In this situation, moreover, it is preferable to provide the flaps 16, 18 with ventilation holes in order to reduce the temperature inside the collector element 2. Such ventilation holes can be furthermore conveniently shielded by means of filtering fabric in order to prevent the access of powder or other agents, and yet maintaining the possibility to dispose the heat picked up in the collector element 2.

If, instead, the solar absorber described in figures 7 to 9 is used, the energy associated to the solar radiation is in part converted into electricity thanks to the photovoltaic cells 44, and in part is used to heat the fluid flowing in the channels 38, 40.

In such a way, the concurrent production of electricity and heated fluid is achieved. It is clear that, together with the solar collector 1 it is necessary to have devices for the circulation of the fluid in the channels 38, 40 as well as means for storing the electric energy possibly transformed. Such devices are of known type and within the reach of the man skilled in the art and will not be described herein .

With reference to figures 10 to 13 an advantageous variant of the solar collector 1 is identified by the reference number 100. The solar collector 100 comprises a plurality of collector elements 102. Each collector element 102 is manufactured by longitudinally connecting two sheets of transparent polymeric material 102A, 102B along the junction ^' lines 103. Adjacent collector elements 2 are connected by joining the strips 103A attached thereto, by way of example but not exclusively, by means of heat-sealing/j oining .

Each sheet 102A, 102B includes its own transparent portion 10.4A, 104B and its- own internally reflecting portion 106A, 106B. The union of the portions 104A, 106A of the sheet 102A with the portions 104B, 106B of the sheet 102B allows to obtain a transparent portion 104 and an internally reflecting portion 106, which are functionally analogous to the portions 4, 6.

The internally reflecting portions 106A, 106B are preferably realized by depositing a layer of reflecting material onto the sheets 102A and 102B, in order to give the portion 106 the capability of reflecting the light .

Each collecting element 102 is provided with support means arranged for receiving the solar absorber 8.

Such support means comprise a sheath 110 having a duct 112 arranged to receive the solar absorber device 8. The sheath 110 is bound to the internally reflecting portion 106 by a flexible longitudinal strip 114 positioned along the corresponding junction line 103.

At opposite ends of each collector element 102 respective flaps 116, 118 having an almond-like shape with cusp-like ends 116A, 118A and integral, respectively, with the sheet 102A and the sheet 102B are formed.

Each foldable flap 116, 118 comprises a free edge

116B, 118B and is articulated with respect to the corresponding sheet 102A, 102B along a respective folding line 116C, 118C, symmetrical to the corresponding free edge with respect to an ideal axis passing through the aforesaid cusp-like ends 116A, 118A.

In particular, portions of the folding lines 116C, 118C approximating a parabolic profile are associated to the portions 106A, 106B, while portions of the folding lines 116C, 118C approximating a circular profile are associated to the portions 104A, 104B.

Each flap 116, 118 includes a respective rectangular opening 120, 121 identical to one another, and positioned on the mid line of the flaps along an axis passing through the cusp-like ends 116A, 118A.

The solar collector 100 operates as follows.

Referring to figures 10, 11, each collector element 102 is deformable from a substantially flat shape, corresponding to a collapsed configuration, to a substantially tubular shape, corresponding to a deployed configuration. The figures 11 to 13 show part of a deployment sequence, which occurs in a completely similar manner to that described for the solar collector 1, wherein the application of a transversely oriented force T (Fig. 12) on the junction lines 103 of each collector element 102 is envisaged. Such force T causes an outward buckling of the portions 104A, 106A and 104B, 106B, which confers to the collector element 2 a substantially tubular shape. This shape is maintained, as previously described, by folding the flaps 116, 118 towards the interior of the element 102 or by either alternatively, applying a traction action acting in the opposite direction to the forces in figure 11, exerted through appropriate traction members, anchored to appropriate supports or in the broad sense to the ground. In an improved variant, such traction members traverse the tubular part and are loose when said tubular element is in the collapsed configuration, while they are taut when the tubular element is deployed or the set of tubular elements is deployed. In such a situation the taut traction member can usefully contribute to support and maintain in place the sheath that contains the absorber.

The folding occurs sequentially and the position of the openings 120, 121 is such that they are aligned when the folding is completed.

However, since the sheath 110 is bound to the portion 106, which similarly to the portion 6 is arranged for the contact with the ground or the support structure, it is preferable to insert the solar absorber 8 (either in the embodiment shown in figures 2, 3, 6F or in the embodiment of figures 7 to 9) in the channel 112 after folding the flaps, with the sheath 110 hanging from the upper part and the cylindrical surface facing the lower side, with a subsequent reversing to bring the parabolic surface at the bottom.

Alternatively, in the variant with tensioning wire described above, such wire constrained to the sheath contributes to the positioning thereof and to maintain such positioning.

As a consequence of what previously described, moreover, it is to be noted that the shape given to the collector element 2 by the flaps 116, 118 approximates that of a parabolic reflector, wherein the internally reflecting portion 106 takes a shape that substantially approximates that of a parabola, while the portion 104 takes a shape that substantially approximates that of a semicircle .

Similarly to the solar collector 1, the openings 120, 121 support the solar absorber device 8 and contribute to the correct positioning of sheath 110 when each collector element 102 is in the deployed position.

Advantageous variants of the solar collectors 1, 100 are shown in Figures 14, 15. Such variants are indicated respectively by the numbers 1' and 100'. The components of the solar collector 1' which are identical to those of the solar collector 1 are indicated with the same reference number. The solar collector 1' includes, applied to the transparent portion 4, at least one diverging linear Fresnel lens, oriented longitudinally and indicated as a whole with L, . The Fresnel lens is adapted to increase the acceptance angle of the incident solar radiation for each element collector 2.

Similarly, the solar collector 100', whose components identical to those of the solar collector 100 are indicated with the same reference number, includes, applied to the transparent portion 104, at least one diverging linear Fresnel lens, oriented longitudinally and indicated as a whole with L'. The function of the lens L ' is identical to that of the lens L.

A further advantageous variant of the collector 1 is illustrated in Figures 16, 17, 18. The collector 1 includes a wire-like element 50, e.g. a rope made of natural fibres, a wire made of metal or polymeric material, which transversally goes across the collector element 2 and exits through two openings 52 (Figs. 16, 18) provided on the sheets 2A, 2B. The wire-like element 50 is preferably provided, at one end, with a properly applied head 53 and a corresponding abutment element 53A, while the other end is free. A sleeve 54 is fitted onto the element 50 and it is freely movable with respect thereto. With reference to figures 16, 17, the wire-like element 50 is arranged to vary the geometry of the collector element 2 from the flattened shape to the substantially tubular shape previously described.

Starting from a condition, illustrated in Figure

16, 'in which the collector element 2 is collapsed and is in the substantially flat shape previously described, a traction force can be exerted on the wirelike element 50, while holding the collector 2 still.

The wire-like element 50 drags the head 53 and the abutment element 53Ain abutment with the edge of the junction strip 3A adjacent thereto, while the opposite edge 3A is kept steady by a manual action exerted by a _. user. By carrying on with the application of a traction force on the wire-like element 50, and having both the edges 3A of the collector element bound (by the head 53 and the abutment element 53A on one side and by the hand of the user on the other side) to move only in a way that causes the mutual approach thereof, a buckling of the sheets 2A, 2B which confers to the collector element 2 the substantially tubular shape previously described is produced.

The length of the sleeve 54 is selected so as to be equal to a maximum transverse dimension of the collector element 2 when it takes the substantially tubular shape, substantially corresponding to the distance between the cusp-like ends 16A (or 18A) .

Thus, upon achieving the abovementioned configuration, a further action on the wire-like element 50 does not cause any further buckling of the sheets 2A, 2B because the sleeve 54 is in contact with the sheets 2A, 2B and prevents a further movement thereof. Naturally, in order for the shape given to the collector element 2 to be maintained, it is necessary to fold the flaps 16, 18 as previously described.

Clearly, the overall dimensions of the sheath 10 must be chosen so as not to interfere with the wirelike element 50 and the sleeve 54. It is to be noted that the wire-like element 50 can pass through an arbitrary number of collector elements 2, which allows to make the collector 1 with a wire deployment system, wherein inside each collector element a sleeve 54 is inserted. Preferably, in this case several parallel wire-like elements 50 can traverse the collector 1, thus equalizing the deployment action along the entire length of the individual collector elements 2. The presence of the openings 52 furthermore allows the normal overlap of the strips 3A of adjacent collector elements, thereby making it possible to join them according to the manner described with reference to figures 7 , 8.

The solar collectors 1, 100 according to the present invention have a number of advantages. First of all, the solar collectors 1, 100 are intrinsically light as they are made of polymeric material, which favours the transportability thereof. The collapsibility thereof also makes them suitable for transportation in small cars or private vehicles, and in any case it does not require the use of commercial vehicles such as vans or similar.

Being both made of sheets of polymeric material joined together along longitudinal edges, the production process required for the manufacturing thereof is well known, well established and has low cost. So they combine the low cost with the possibility of transforming the energy associated to the solar radiation into electric energy or exploiting it for heating a fluid, thereby constituting a source of renewable and low cost energy for a . plurality of different activities including outdoor sports and/or camping .

Obviously, the construction details and the embodiments may widely vary with respect to what has been described and illustrated without departing from the scope of protection of the present invention, as defined by the attached claims.

For example, it is particularly advantageous to integrate the solar absorber device 8 and the sheath 10, 110, having the function of support means for the solar absorber device, can be replaced with an extruded member made of polymeric material. A plurality of photovoltaic cells drowned inside the extruded member made of polymeric material (or simply supported thereby) , together with the necessary electrical connections, constitutes therefore a solar absorber device .

In this way the solar absorber device is integrated with its own support means and there is no need to provide the openings 20, 21, 120, 121: thus the deployment of the solar collectors 1, 1', 100, 100' would be further simplified.

nevertheless, as an alternative to the photovoltaic or photovoltaic-thermal absorber 8 described herein, it is possible to use a normal solar heat absorber, that is of the type comprising a tubular body susceptible of containing water or other fluid.