PASSIVE VENTILATION SYSTEM FOR GREENHOUSES

Abstract

A passive ventilation system for greenhouses, comprising gutters (11), a closing plate (3), and an opening and closing device, characterized by having two independent gutters (11), separated from each other at the junction of the greenhouse's roof arches and uprights, and an opening and closing system (13) (16), by means of a plate (3) attached to one of the gutters. The invention is characterized by the arrangement of said two gutters (11), separated by a free space of 20-30 cm (or more if desired), in which one of them has attached a polycarbonate plate or other similar material (3) that allows, by means of the manual opening mechanism (13) (16), the control of the temperature and humidity inside the multi-tunnel greenhouses, according to the desired opening.

Description

Passive ventilation system for greenhouses Technology sector Greenhouse construction. Background of the invention Modern greenhouses have their most immediate precedent in the so-called "greenhouses" or glass houses that both Anglo-Saxons and other Central European countries (Holland, Germany...) developed during the 19th and early 20th centuries as dwellings for the establishment of botanical gardens and other experiments. The subsequent emergence of petroleum-derived products, such as polyethylene, discovered in 1938, made it possible to replace glass in greenhouses with virtually the same properties, but at a much lower cost and more manageable. Furthermore, thanks to its flexibility and lightness, it began to be used in increasingly simpler structures with larger surface areas, almost all of which were made of metal or wood. Regarding current metal structures, with the exception of those built from aluminum (Venlo-type greenhouses), we can basically divide them into two models based on their external shape: single tunnel and multi-tunnel. In our case, we will focus exclusively on the second option, the multi-tunnel, which is where the innovation we propose is applicable. In this second case, the passive or non-forced ventilation systems currently available are based solely on two methods: ventilation through the sides of the greenhouse, by means of large longitudinal windows, the opening or closing of which is controlled by a roll-up polyethylene sheet parallel to these sides from the outside; and ventilation installed at the top of the greenhouse, by means of roof windows, commonly called butterfly windows. Explanation of the invention The proposed innovation essentially consists of replacing the traditional gutter found in all multi-tunnel greenhouses, which is a single unit, with a system of two independent and separate gutters. The traditional gutter collects rainwater from both half of the greenhouse's roof arch. Our proposal involves splitting this traditional gutter into two halves, so that each half is independent and, logically, receives rainwater exclusively from the half of the roof arch to which it is attached. Once split, the two resulting gutters will be raised 20-30 cm above the original position of the traditional gutter, following the curve of the greenhouse's roof arch and remaining anchored to it. The consequence of this separation is the appearance of a space between the aforementioned gutters, a space that will allow the hot air contained in the greenhouse to escape to the outside, in accordance with the mechanism provided to achieve this purpose. To this end, and on the vertical side of one of the gutters, we will attach, using appropriate hinges, a sheet of polycarbonate or similar material, with a width at least equal to the distance between the two gutters. This sheet, when closed, will prevent the entry of cold air when outside temperatures are low, but in warm weather, when the mechanism is opened, it will allow the warm air contained within the greenhouse to escape. The opening and closing operations of the proposed invention will be facilitated by the use of a crank which, connected to the polycarbonate sheet, will allow, through appropriate movements, the opening or closing of the space between the two channels. Finally, this crank will remain in the desired position by means of a pin that connects, through a hole, the crank to a sectorial positioning plate which, in turn, has been drilled with various holes to achieve the most convenient opening, as previously mentioned. It is clear that for this innovation to have the desired effect, two conditions must be met. The first, which is a direct consequence of the proposed innovation, is the existence of a double roof within the greenhouse. This double roof will clearly separate the space within the specific cultivation area from the volume contained in the crescent formed by the greenhouse's roof arches. The second condition is the need to remove the hot air contained in this space, making the presence of roof vents, such as those already available on the market, absolutely essential. Having established these premises, we should point out that the advantage offered by the inter-tunnel ventilation system proposed in this innovation is the ability to have two distinct and independent environments within the same greenhouse. We cannot comment on the effectiveness of this system in reducing high temperatures inside the greenhouse during the summer months, as we have not been able to verify this and, obviously, there are no studies or research on the matter. However, we can offer some evidence regarding the very important and beneficial increase in the greenhouse's interior temperature during the cold winter months.In addition to the fact admitted in various studies that, with the placement of a double night chamber in multi-tunnel greenhouses, an increase of between 2 and 3 degrees is achieved in them, with the application of our innovation it is possible to achieve a thermal difference between the outside of the greenhouse and the interior area intended for cultivation, that is, the space between the roof and the floor of between 5 and 7 degrees, according to our experience with a small greenhouse of just over 1,000 m2 in the Castilian plateau and in the coldest months of winter: November, December, January and February.This thermal difference has been achieved by placing polyethylene skirts or curtains (the gauge is irrelevant, beyond their durability) around the entire perimeter of the greenhouse, including the fronts, from the confluence of the double roof with the fronts and sides to the ground, so we are talking about a double greenhouse, in the broadest and most literal sense of the phrase, a double greenhouse that, without the help of our innovation, would be impossible to implement permanently. Brief description of the drawings Figure 1 shows the innovation as a whole, highlighting, firstly, the position of the two gutters (11) in relation to the roof arches (6) of the structure that make up the greenhouse frame. These roof arches connect to the upright post (7) by means of a right-angle plate (1) with its corresponding clamps (8), all joined by through bolts (5b). At a prudent and convenient distance, we will place the gutters which will be joined, firstly, to the zenithal arches (6) by means of two through screws (5c), one of which will also serve to anchor the omega profile (2) which, by means of the appropriate strip of wood or other material, will serve to support the polyethylene sheet (17) that covers the greenhouse. Once the previous operation has been carried out, we will place horizontally an angle profile (9) parallel to the base of the gutters and in contact with them, which will be anchored to the zenithal arches by means of two through screws (5d). Once this phase is completed, on the vertical faces of the channels (11), we will attach two angle profiles (10) by placing two through screws (5e). These two angle profiles will protrude a few centimeters below the bases of the channels, enough so that we can join them to the horizontal profile (9) using the corresponding through screws (5f). In parallel with these tasks, we will cut a sheet of cellular polycarbonate (3), or similar material, with a width that allows us to conveniently cover the gap between the two coves and with a length that is available on the market. Several hinges (4) will be attached to this polycarbonate sheet at a suitable distance. These hinges will serve to join the polycarbonate sheet to a tubular profile (12) by means of one of their wings, while the other part of the hinge will be attached to the vertical wall of the channel using appropriate through bolts (5g), as can also be seen in Figures 1 and 3. Once this phase is completed, we will proceed to fit a crank (13) to the channels, allowing us to operate the plate (3) as we see fit, as shown in Figure 2. For this purpose, we will use the aforementioned crank, one end of which will be inserted into the tubular profile (12), with the handle (14) at the other end. Above the handle, we will drill a small hole in the crank to allow us to attach a pin (15), through which we can fix the crank in different positions, according to the different holes that have been previously drilled in a sectorial positioning plate (16). This crescent-shaped sector plate will be attached to the beginning of the channel that supports the polycarbonate sheet or similar material (3) using the same screws (5e) used to anchor the angle profile (10), as can be clearly seen in Figure 2. Figure 3 provides an overall perspective of the proposed innovation. Finally, Figure 4 shows the three gutter profiles to be protected. Model (11a) represents the simplest form, as it requires attaching an omega profile to the end of its angled face, as seen in Figure 1, to secure the polyethylene film covering the greenhouse roof. Model (11b) incorporates the omega profile integrated with the rest of the gutter's sheet metal, with one wall of the omega profile being double-layered and the opposite face single-layered. This feature allows the angled side of the gutter to be parallel to the tubular profile (6), enabling it to be attached to the tubular profile (6) under the same conditions as the previous model.Finally, in the figure shown as a model (11c), we see how the achievement of the omega profile integrated into the channel based on the fact that both faces of it are simple, that is, that there is no double wall, forces us to slightly fracture the oblique face of the channel to allow the union of the channel to the structural tube (6) to be complete, with which we will achieve that the fixing of it through the two through screws (5c) offers full guarantees. Legend 1.- Square plate 2. Omega profile 3.- Cellular polycarbonate sheet 4.- Hinge 5a.- Through screws for the bracket-right post plate 5b.- Through bolts for sheet metal bracket-clamps 5c.- Through screws channel-central arch 5d.- Through bolts horizontal angle profile-zenithal arch 5e.- Through screws vertical angle profile-channel 5f.- Through bolts vertical angle profile-horizontal angle profile 5g.-Through screws for vertical side hinge channel 5h.-Through screws hinge-cellular polycarbonate plate-tubular profile 6.- Overhead arch greenhouse structure 7.- Greenhouse structure upright post 8.- Clamps for sheet metal brackets - greenhouse roof arches 9. Horizontal angle profile 10.- Vertical angle profile 11.- Gutter 12.- Tubular profile 13.- Crank 14.- Handle 15.- Pin 16.- Sectoral positioning plate 17.- Polyethylene sheet Preferred embodiment of the invention Taking Figure 1 as a reference, the application of this innovation is extremely simple. Once the two gutters (11) that make up the innovation have been anchored to the structural tubes of the greenhouse (6), the polycarbonate sheet (3) will be attached to one of them by joining it to the vertical wall of said gutter through a hinge (4) which, in turn, will connect said sheet to the tubular profile (12), as we have already indicated in the previous chapter. Once this first phase is completed, we will then provide greater security and strength to the gutters by joining them with an angle bracket (10) attached vertically and parallel to the vertical flange of the gutter (11) using two through bolts (5e). This vertical angle bracket will then be joined to another horizontal angle bracket (9) using a through bolt (5f), and this horizontal angle bracket will be joined at its ends to the tubular structure (6) of the greenhouse using through bolts (5d). Finally, we will point out that, of the two through screws (5c) that hold the oblique wing of the gutter to the tubular structure (6), the upper screw will also serve to anchor to the aforementioned structural tube the omega profile (2) that will house inside the polyethylene sheet (17) of the greenhouse roof, by means of a wooden strip or other suitable material. Once all these operations have been carried out, all that remains is to attach the manual opening and closing mechanism, as shown in figure n°2, so that we can activate the mechanism according to the temperature needs inside the greenhouse.

Claims

1. A passive ventilation system for greenhouses, comprising gutters (11), a closing plate (3), and an opening and closing device, characterized by having two independent gutters (11), separated from each other at the junction of the greenhouse's roof arches and uprights, and an opening and closing system (13) (16), by means of a plate (3) attached to one of the gutters. The invention is characterized by the arrangement of said two gutters (11), separated by a free space of 20-30 cm (or more if desired), in which one of them has attached a polycarbonate plate or other similar material (3) that will allow, by means of the manual opening mechanism (13) (16), the control of the temperature and humidity inside the multi-tunnel greenhouses, according to the desired opening. 2.A passive ventilation system for greenhouses, according to claim 1, characterized in that it comprises an oblique wing that is attached by means of two through screws (5c) to the structural tube (6), a horizontal base with sufficient width to accommodate a person's footprint, and a vertical wing to which the polycarbonate sheet (3) or other similar material is attached, as well as the opening and closing system (13) (16) for the proper control of ventilation.

3. A passive ventilation system for greenhouses, according to claim 1, which includes the formation of a "U" profile with one of its sides doubled on said oblique side, to hold the polyethylene film of the roof (17), a suitable horizontal base sufficient to accommodate a person's footprint, and a vertical wing to which the polycarbonate sheet (3) or other similar material is attached, as well as the opening and closing system (13) (16) for the proper control of ventilation. 4.A passive ventilation system for greenhouses, according to claim 1, characterized by a modified channel at its oblique end (11c), which includes the formation of a "U"-shaped profile at said end to hold the polyethylene film of the roof (17), a suitable and sufficient horizontal base to accommodate a person's footprint, and a vertical flange to which the polycarbonate sheet (3) or other similar material will be attached, as well as the opening and closing system (13) (16) for the correct control of ventilation.

5. A passive ventilation system for greenhouses, according to claim 1, characterized by a manual opening and closing system with a crank (13) and its corresponding handle (14) attached to the tubular profile (12) that will actuate the movement of the polycarbonate sheet; this movement is regulated by means of the crank and its various anchors to the sectorial positioning plate (16).