FIELD OF THE INVENTION

The invention relates to the field of solar collectors.

BACKGROUND

Solar water heating systems are commonly used since the 1980's, usually in countries which experience many sunny days during the year. Such systems usually include a solar collector coupled to a water tank. The solar collector is commonly a hollow metal grill housed within a box having a transparent side pointed at the sun. The grill operates as an inverse radiator; solar energy is absorbed in the hollow metal grill and heats the water flowing therein. The radiator-like structure of the grill causes the water therein to have a relatively large contact area with the grill, thereby efficiently utilizing the solar energy. The heated water flows to the tank, from which it is dispensed to the consumer.

The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the figures.

SUMMARY

The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope.

One embodiment provides a solar collector which comprises: a box-shaped housing comprising an opening in one of the facets of the housing; a hollow plastic grill disposed within the housing and having a longitudinal dimension smaller by at least 1 centimeter than a longitudinal dimension of said housing, to allow expansion of said grill upon absorbing solar energy; a pipe in fluid communication with said grill and passing through said opening; and a seal disposed about said pipe and at least partially within said opening, to allow said pipe to sealingly slide through said opening when said grill expands and shrinks. In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the figures and by study of the following detailed description. BRIEF DESCRIPTION OF THE FIGURES

Exemplary embodiments are illustrated in referenced figures. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.

Fig. 1 shows a solar collector in a front perspective view;

Fig. 2 shows the solar collector of Fig. 1 in a top view;

Fig. 3 A shows a grill contained in the solar collector of Fig. 1, in a front perspective view;

Fig. 3B shows an enlargement of a region A of Fig. 3 A;

Fig. 4 shows the grill of Fig. 3 A in a rear perspective view; and

Fig. 5 shows an outlet pipe of the grill of the previous figures in a side view, in which a left facet of a housing of the solar collector is not shown, to allow visibility of the outlet pipe.

Fig. 6 shows a an outlet pipe of a grill in accordance with additional embodiment of the present invention, depicted in cross section, in order to show the seal that maintains the sealing between the outer circumference of outlet pipe and the housing while providing for the linear movement (sliding) of the outlet pipe upon expansion.

DETAILED DESCRIPTION

Disclosed herein is a solar collector in which an inner, hollow plastic grill is allowed to expand and shrink within a box-shaped housing while preserving impermeability of the housing.

Reference is now made to Figs. 1-5, which show a solar collector 100 and/or various parts thereof, in accordance with an embodiment. Solar collector 100 may include a housing 102, optionally box-shaped. Five facets (bottom, right, left, front, rear) of housing 102 may be made of a rigid material such as aluminum. The sixth, top facet of housing 102 may be at least partially made of a transparent or translucent material, such as glass, polycarbonate, polymethyl methacrylate (PMMA) or the like, to allow solar radiation to penetrate into the housing. Solar collector 100, when installed, may be positioned such that its top facet is exposed to solar radiation from above, and its front facet (adjacent inlet pipes 106, 108) is lower than its rear facet (adjacent outlet pipe 110).

Housing 102 may contain a hollow plastic grill 104. Grill 104 may be wholly or mostly made of plastic, optionally black to enhance solar energy absorption. Grill 104 may include multiple plastic pipes 112 which are optionally arranged in a single layer. Solar radiation may impinge on and be absorbed in pipes 112, heating them and in turn also the water inside them. The radiator- like structure of grill 104 causes the water therein to have a relatively large contact area with pipes 112, thereby efficiently utilizing the solar energy. Pipes 112 may be secured to each other using a structure such as a bridge 114, to prevent their movement and maintain fixed spaces between them. Optionally, grill 104 may include a rear basin 116 and a front basin 118 to which pipes 112 open. One or multiple inlet pipes 106, 108 may be integrally formed with front basin 118 or be connected thereto. Inlet pipes 106, 108 may be in fluid communication with front basin 118 and therefore with the rest of the interior void of grill 104. Relatively cold water may enter grill 104 through inlet pipes 106, 108. The water may then be heated inside pipes 112 and flow upwards to rear basin 116. From there, the relatively hot water may exit solar collector 100 through an outlet pipe 110 which may be integrally formed with or connected to grill 104.

Naturally, grill 104, and especially its pipes 112, tend to expand as their temperature rises, and shrink when the temperature decreases. Advantageously, to facilitate that expansion and shrinkage, grill 104 is shorter than housing 102 by a certain measurement L (see Fig. 2), for example, 1-15 centimeters. In some embodiments, L is between 1-3 centimeters, 3-5 centimeters, 5-7 centimeters, 7-9 centimeters, 9-11 centimeters, 11-13 centimeters or 13-15 centimeters. The term "between" is intended to include any value, integer or fraction, within the denoted range. L may be a distance along a longitudinal dimension 124 of solar collector 100.

Further advantageously, to maintain housing 102 impermeable despite the expansion and shrinkage of grill 104, a seal 122 (see Fig. 5) may be disposed between outlet pipe 110 and the opening (not indicated) in housing 102 from which the outlet pipe emerges. Seal 122 may be generally shaped as a disc, an O-ring or the like, having an outer rim sealingly coupled to the opening and an inner rim sealingly coupled to the outer circumference of outlet pipe 110. Seal 122 may be made of a flexible material such as rubber. Optionally, seal 122 is an O-ring having a shore hardness of between 50 and 80. When grill 104 expands, outlet pipe 110 is pushed further out the opening in housing 102. Conversely, when grill 104 shrinks, outlet pipe 110 is pushed further into housing 102 through the opening. In both cases, outlet pipe 110 slides over the outer rim of seal 122 in a tight manner, such that seal 112 maintains the sealing between the outer circumference of outlet pipe 110 and the housing 102. This prevents ambient humidity, dirt and/or the like from penetrating into the housing.

Furthermore, as shown in the figures, the sliding pipe, which is outlet pipe 110 in the above exemplary embodiment, and one or more non-sliding pipes, namely inlet pipes 106, 108, are disposed in perpendicular facets of housing 102. Advantageously, this anchors grill 104 to housing 102 on one side (the one where the non-sliding pipes are located), and allows the grill to move on the opposite side (the one where the sliding pipe is located).

Reference is now made to Fig 6, which shows a an outlet pipe 6110 of a grill 6104 in accordance with additional embodiment of the present invention, depicted in cross section, in order to show the seal 6122 that maintains the sealing between the outer circumference of outlet pipe and the housing 6102 while providing for the linear movement (sliding) of the outlet pipe upon expansion (in the direction of arrow 6111), due to absorbing of solar energy.

In another embodiment (not shown), a skirt-type seal may be used, in which the inner rim of the seal is adhered to the outer circumference of the outlet pipe and the outer rim of the seal is adhered to the circumference of the opening. The skirt-type seal includes a sufficient amount of material between its inner and outer rims, to allow the inner rim to move together with the outlet pipe outside of the housing when the grill expands. Typically, when the skirt-type seal is spread out, the distance between its inner and outer rims is of a length which is it least the amount of movement of the outlet pipe from the fully shrunk state of the grill to the fully expanded state of the grill.

In other embodiments (now shown), an inner grill may be expandable along a different dimension of its housing, or even along multiple dimensions thereof. A seal may be provided for an inlet pipe, for each of multiple inlet pipes, for each of an inlet pipe and an outlet pipe, or for each of multiple inlet pipes and an outlet pipe. The principle of operation in which the impermeability of the housing is maintained - is the same for these embodiments as in the illustrated embodiment above. In an exemplary embodiment (not shown), seals are provided for the outlet pipe as well as for the two inlet pipes. In this embodiment, the grill may be shorter than its housing in two perpendicular dimensions, and to two different extents: In the dimension of the sliding of the outlet pipe, the difference in size between the grill and the housing may be relatively high; in the perpendicular dimension, along which the inlet pipes slide, the difference in size between the grill and the housing may be relatively low. This allows the grill to expand more in one dimension and less in the perpendicular dimension. With reference to the figures, pipes 112 of grill are shown to extend along the dimension of sliding of outlet pipe 110. Naturally, due the inherent structure of pipes in general and pipes 112 specifically, they tend to expand more along their length dimension than along their diameter. Namely, to allow grill 104 to freely expand, more space is required at the ends of pipes 112 than laterally to the pipes.

In the description and claims of the application, each of the words "comprise" "include" and "have", and forms thereof, are not necessarily limited to members in a list with which the words may be associated. In addition, where there are inconsistencies between this application and any document incorporated by reference, it is hereby intended that the present application controls.