FIELD OF THE INVENTION The present invention refers to an environmentally friendly grain drying apparatus. BACKGROUND OF THE INVENTION

The appropriate grain drying process is performed in order to reach such a quality of the grain that preservation thereof is guaranteed while it is commercialized.

More particularly, drying consists of removing humidity from the product until it reaches the adequate degree of humidity. This process must be done immediately after grain harvesting, washing, or wet processing.

At this stage of the drying process there are grains which tolerate a maximum temperature and others which are affected at that maximum temperature. Likewise, the optimum degree of humidity being required in each grain will depend on the type of grain that is intended to dry.

The most artisanal techniques which are currently used depend on the producers being small and medium-sized producers or large-scale producers. These go from the use of frames exposed to sun light, to the use of mechanical dryers. In the case of frames which correspond to the most artisanal use, they expose the grains to environmental pollution such as dust, animals or chemicals.

There is equipment for drying vegetal products including a thermal collector which turns solar energy into thermal energy. This equipment has a heat transfer system. The solar thermal collector is positioned in front of the light source and is thermally connected to the heat transfer system, thus heat is kept in the drying chamber. This chamber comprises an opening for heat to be released and a opening for humidity to be released. Grains are kept in the chamber until the optimum level in the grain drying is reached. An example of a known apparatus is shown in document WO2002061356A1. More particularly, a device is described which is intended for reaching drying of different types of food such as onion, tobacco, cereals, etc.; this is based on a system having the shape of a small house, where the flow of fresh air is heated with solar heat and with a small furnace, and once heated the air is directed to a drying chamber where food is kept. The solar collectors are placed on the house roof.

Additionally, document US4099338A is also known wherein a solar thermal dehydrator is described which comprises a plurality of perforated trays being vertically separated where the food to be dried is placed. Sun light entrance is permitted into this site, and the air passing through the drying chambers is heated such that the food placed onto the perforated trays is dehydrated.

It is also known, according to document US5960560A, a kind of solar drying stove using the greenhouse effect. In this case the humid material, or food, is placed inside a solar greenhouse being substantially closed. This greenhouse has a roof being transparent to solar radiation. The temperature and humidity inside the solar greenhouse is kept within a predetermined range. By controlling humidity inside thereof, a controlled drying is obtained.

Another known document is US7748137B2 that describes the use of a granary as a stove which heats the grains, using solar energy for the auxiliary heating. It is characterized because it is shaped as a granary and the roof thereof allows the sun lights to pass through. It has a dehumidification chimney.

Finally, document CN201059849Y is also known, disclosing a grain drying system which is based on a layer parallelepiped, featuring a distributor, a discharge hopper, fans, heat exchangers, a moisture meter, etc. The hopper vibrates and the system can be adapted to different grains. The operation thereof is electromechanical.

DESCRIPTION OF THE INVENTION

The present invention refers to a grain drying apparatus having the shape of a polyhedron with an inlet for introducing the grain into the apparatus, wherein the apparatus comprises: a base which in turn comprises a depositing surface having a vibration system for receiving grains through the inlet and for these to move and change the position thereof periodically, at least a transparent wall so as to allow sun rays to get inside the apparatus, comprising an incoming and outgoing air system so as to ventilate the area inside the apparatus, a transparent roof so as to allow sun rays to get inside the apparatus, a folding base which folds and unfolds from two sides of the transparent base, and a transparent folding roof which folds and unfolds from the two sides of the transparent roof and allows sun rays to get inside the apparatus.

More particularly, the transparent wall is flexible so as to connect the detachable base with the detachable roof, in order to vary the volume and capacity of the apparatus.

The folding base and roof can be expanded and/or compacted, such that the area used for the grain drying can be increased by about 50% or even 100% of the fixed surface. Additionally, the apparatus comprises folding solar panels, which fold and unfold from the two front surfaces of the transparent roof.

These folding solar panels are linked to an electric energy regulation and accumulation system, for regulating and accumulating the electric energy that these folding solar panels generate.

The electric energy regulation and accumulation system supplies the incoming and outgoing air system with power. This system for regulating and accumulating electric energy, supplies the vibration system with power.

Finally, both the incoming and outgoing air system, and the vibration system are linked to an electronic control system which regulates the operating parameters thereof so as to emulate a grain drying as that produced under solar exposure.

The electronic control system is programmable and controls parameters such as air flow inside the apparatus. Additionally, and by means of the presence of humidity, temperature and solar irradiation sensors placed within the apparatus, the electronic control system controls the desired characteristics being fundamental in the grain drying process, and by means of an alphanumeric visualizing unit it is possible to show the user the values acquired in the sensors.

Additionally, the electronic control system comprises a wireless communication unit so as to transmit the information from the sensors to a user cell phone, which by means of an application keeps a record of the drying levels which are being reached in the system; also including information to the user, by means of a warning signal, indicating if the levels have been reached for the grains to be readily removed from the drying system.

An advantage of this apparatus is that it allows using the electric energy generated by the folding solar panels, and accumulated in the electric energy regulation and accumulation system, in order to provide the required electric energy for the apparatus operation during the night, or under conditions where there are no incident solar rays. Thus, the drying time is reduced by half of the time usually required under solar exposure.

The base and roof thereof can be folded, such that the surface of the drying area can be increased by twice the drying area it features when compacted without being folded. Regarding the characteristics thereof, this grain dryer is mobile for it to be transported from one place to another.

DESCRIPTION OF THE FIGURES To implement the present description being made and in order to provide a better understanding of the characteristics of the invention, according to a preferred practical embodiment thereof, a set of drawings is attached as part of this description, with an illustrative but not limitative purpose, which represents the following: Figure 1. It shows a general top view of the grain drying apparatus in the compacted condition thereof, without the folding base or roof being expanded.

Figure 2. It shows a general front view of the apparatus for grain drying without unfolding of the base or the roof, that is, in the compacted state. Figure 3. It shows a general front view of the grain drying apparatus being expanded, that is, with the folding base and roof unfolded.

Figure 4. It shows a general top view of the grain drying apparatus in an expanded state.

Figure 5. It shows a general side view of the grain drying apparatus in an expanded state, where the unfolded state of the folding solar panels can be observed. DETAILED DESCRIPTION OF THE INVENTION

The following figures are not to scale. Dimensions and/or actual shape of each of the components of the grain drying apparatus may vary. Only the important details of the grain drying apparatus are shown; however, an expert skilled in the art can see how the whole structure may be constructed, without undue experimentation.

The present invention refers to a grain drying apparatus, by means of the exposure thereof to the sun, or in the absence of sun, by emulating the same temperature, humidity and ventilation conditions which take place under sun exposure.

In a preferred embodiment of the present invention, as it is shown in figures 1 to 5, this apparatus (10) having the shape of a parallelepiped comprises: a base (5), transparent walls (1a, 1 b, 7) and a transparent roof (6) which allows solar rays to pass through, a folding roof (6a, 6b) and a folding base (5a, 5b) sliding outwards or inwards of the transparent roof (6) and/or the base of the grain dryer.

More particularly, figure 1 shows a general top view of the apparatus (10) in the compacted state. In the front side, there is an electric energy regulation and accumulation system (4), and an electronic control system (3) intended for control of the drying process, that is, it is in charge of controlling the appropriate parameters and characteristics for an optimum grain drying.

Additionally, figure 2 shows a general front view of the apparatus (10) with the transparent roof (6) thereof in a compacted state. In said frontal side, it can be seen the electric energy regulation and accumulation system (4), the electronic control system (3), the front transparent wall (7), which is transparent for allowing light to get inside the apparatus (10). Additionally, this front transparent wall (7) comprises an incoming and outgoing air system (2a, 2b) required for optimum ventilation inside the apparatus (10), and an inlet (9) for granting access to the inner area of the apparatus (10) for the grains intended to be dried.

Preferably, the incoming and outgoing air system (2a, 2b) is an electric impeller fan and an electric extractor fan, respectively.

It should be noted that the apparatus (10) has inside thereof, on the base (5), a surface for depositing grains, not shown, over which grains to be dried are placed, and it comprises a vibration system so that the grains move and change position thereof periodically.

Figure 3 shows a general front view of the apparatus (10), wherein the folding base (5a, 5b) and the folding roof (6a, 6b), are unfolded so as to increase the percentage of effective surface for grain drying in the base. The folding roof (6a, 6b) is connected to the transparent walls (1a, 1 b) which are inclined in order to allow unfolding of the folding base (5a, 5b). The folding base (5a, 5b) and the folding roof (6a, 6b) are transparent. Figure 4 shows a general top view of the apparatus (10), wherein the folding base (5a, 5b) and the folding roof (6a, 6b) are unfolded. Additionally, the apparatus (10) comprises folding solar panels (8a, 8b) which, in this figure 4, are also in an unfolded state, outside the transparent roof (6) of the apparatus (10). It should be noted that folding solar panels (8a, 8b) slide inwards and outwards of the transparent roof (6) allowing both folding and unfolding thereof.

Finally, figure 5 shows a side view of the apparatus (10), where the folding solar panels (8a, 8b) are unfolded. It should be noted that these folding solar panels (8a, 8b) are linked to the electric energy regulation and accumulation system (4), for regulating and accumulating the electric energy which these folding solar panels (8a, 8b) generate.

Also, the electric energy regulation and accumulation system (4) supplies the incoming and outgoing air system (2a, 2b) and the vibration system with power. Both the incoming and outgoing air system (2a, 2b) and the vibration system are linked to the electronic control system (3) which regulates the operating parameters thereof so as to emulate a grain drying process as that produced under solar exposure.