FR2676615A1 - System for defending crops against frost - Google Patents

Abstract

Method and device for protecting plants against frost by passing a low-voltage electric current through a wire in order to heat them up. A regulator makes it possible to adapt the voltage of the current and thus regulate the heating of the wire in order to adapt the production of heat to the type of frost.

Description

 The present invention relates to a crop defense system against frost and its application device.

 Frosts cause significant damage to young shoots (fruit buds of the vine in particular) rich in water which causes the vessels to burst when the gel causes it to increase in volume, mainly in spring and from a temperature of - 2 C. The crops are then considerably compromised.

 At present, the means of control used to protect plants from frosts are divided between the active means by heating the air and the pre-active or passive means.

 The active means therefore comprise systems which make it possible to heat the air: heaters, candles, fuel oil sprayed, gas ramps, pulrrérisatioll of hot air.Moreover in the active means but which do not directly heat the air we find the control by spraying and stirring air as well as smoke screens.

 The principle of materials by reheating is to provide enough heat to compensate for losses.

 The heaters used on the vineyards include improvements compared to the first existing models: automatic electric ignition by entire rows, regulation of the air supply.

 The number of units per hectare is 200, the consumption of 800 to 900 liters of fuel per hectare and per hour in the event of severe frost.

 With an autonomy of six to seven hours, the protection of one night can be done easily.

 This efficient system, however, poses the problems of investment cost, very large labor for start-up, maintenance and is subject to the vagaries of the regular increase in fuels.

 The candles are cardboard or metal containers of about five kilos containing a fuel (paraffin) and which are available at a rate of 400 to 500 per hectare depending on the forecast size of the jelly. The autonomy of these candles is about seven to eight hours and the results satisfactory. However, the disadvantage lies in the installation, the individual ignition and the nuisances produced by the fumes.

 The "GONOD caloric bread", a mixture of sawdust and paraffin, avoids the nuisance of smoke.

However, its lighting is delicate in the case of high humidity, the combustion is irregular from one bread to another, the autonomy reduced from two to three hours which therefore makes it double the number compared to candles. The results are quite satisfactory, but the implementation of this system is long.

 The use of sprayed fuel reduces the problems of labor, activation and implementation of previous systems. Fuel is supplied under pressure in series of 200 to 300 burners per hectare using pipes The control of pressures and flow rates allows a reduction in consumption compared to heaters bringing it down to 200 to 300 liters per hour and per hectare. Salinlelltation is possible from a pump itself activated by the PTO of a tractor. The efficiency is equivalent to that of the heaters for a lower cost. However, there remains the problem of maintenance (clogging of the nozzles, corrosion of the ramps) and the question of dismantling after each campaign, hence the cost of labor. 'oeusrre.

 The gas ramps are supplied with liquefied gas.

They have the major drawback of storing gas near the plots to be treated and pose safety problems.

Hot air is sprayed using
Foehns which include a burner and a ventilation propeller. Their radiation radius is limited to 30 or 40 ares.

 Among the active means but not aimed at directly heating 1 air, there is therefore the spraying with water and the mixing of air by wind turbine as well as the projection of mists and fumes.

 The sprinkling of water is a means of struggle based on the physical principle by which a kilo of water which turns into ice releases 80 kilocalories. The calories produced therefore prevent the temperature from falling below zero, the fruiting buds to be protected being paradoxically caught in the ice which protects them, without however the temperature falling below zero degrees.

 Spray sprinkler systems generally have a main line, buried or not, which distributes the calf through secondary lines.

 Sprinklers then distribute the water evenly in the plots.

 The main interest lies in the unanimously recognized efficiency and automation of operations as well as the non-polluting aspect of this system.

 However, the spraying requires a very good technicality, in particular with regard to the triggering of the operation, the delay or the advance of which can produce catastrophic results (the triggering being decided according to the dew point, if the latter is poorly evaluated, jelly is favored by spraying).

 Likewise, the problem of water supply remains crucial and the needs of the order of 400 to 500 m per hectare and per night therefore impose the proximity of a sufficient source such as river, lake or pond.

 The repeated contributions can paradoxically favor the frosts the night following a treatment and also involve phenomena of root asphixia.

 The air circulation system allows the hottest layers of air to be brought down to ground level. 11 consists of a propeller rotating at the top of a tower in a vertical plane (wind turbine) at medium speed of 600 rpm. This is powered by a motor and protects the plots over a radius of 150 meters.

 If the implementation is easy, the efficiency of this system remains limited by the height and the importance of the thermal ceiling.

 The formation of smoke consists in creating a screen sending back the infrared rays towards the ground. The nature of the smoke produced by smoke bombs lends itself rather badly, not being close enough to the composition of the mists to be really effective, which is also the case with burnt tires.

 Passive or preventive means include the hilling of young plantations, the suppression of weeds, the delay in pruning.

 These systems, whatever they are, do not make it possible to locate the production of calories capable of saving the organs of plants sensitive to frost at the level, or even in contact with them, in particular fruit buds.

 However, in viticulture in particular, the risk of frost is - 2 C.

 Convection jellies, known as black spring jellies, are formed by the arrival of a mass of cold air.

The temperatures can drop in this case to - 5 or even - 6 C.

 Radiation jellies, known as white jellies, are caused by loss of the heat stored by plants and the ground during nights with clear skies and dry weather.

 The temperatures then drop to around - 3 C.

 Evaporative frosts occur after a cold rain and a dry wind which causes water to evaporate, this phenomenon requiring the loss of calories to be achieved.

 It is therefore observed, in all cases, it is necessary to provide the plants with the quantity of calories lost, which varies according to the types of jellies.

 The device according to the invention solves this problem.

 The present invention makes it possible to provide plants, vines or fruit trees, for example, with a source of heat thereto, by circulating an electric current in the wire or wires used for trellising the vegetation in order to cause 1 ' warming up.

 By varying the supply voltage, it will therefore be possible, by using the yarns of the type provided according to the present invention, to adapt the number of calories produced to the type of jelly.

 Similarly, according to the device for implementing the invention, the diffusion of calories takes place at the sensitive areas of plants, mainly fruit buds, or in their immediate vicinity.

 In fact, for plants grown in espalier, the trellis wire or wires ensure, according to the device for applying the invention, the role of heat diffuser, captured by the vegetation linked on these wires and diffused by conduction to the this whole.

 For the case where the plants come to be too far from the wires, it is provided in the application of the present invention, to place the wire close to the vegetation and especially to its sensitive areas by stretching it on stakes placed way to diffuse heat next to them.

 According to the present invention, the wire used has sufficient mechanical strength to support the vegetation and fulfill the role of trellising and lifting (in particular the case of the vine).

 The device for implementing the invention provides for the use of wires consisting of a core, coated with an insulator and a sheath around it.

 The so-called monofilament wires, with and without cold ends, nickel-chrome or ferro-nickel or nickel only core, or "BALCO" (registered trademark), mineral insulation and sheath in stainless steel or ICONEL (registered trademarks, products of the company THERMOCOAX, are perfectly suited to the implementation of the device according to the present invention.

 Similarly, the wires sheathed with PVC or "Teflon" (registered trademark) polyethylene, with a chromium-nickel core can be used in the application of the present invention (the elements mentioned in this paragraph are not to be considered as being restrictive).

 The device according to the present invention provides a supply according to safety standards in low voltage, alternating or direct current.

 A 1-volt battery (value given by way of example but not limiting) easily supplies the monofilaments and can be recharged, according to the device for implementing the invention, by a generator.

 The implementation of the present invention can be done manually or using a thermostat triggering the passage of electric current, the voltage of which will be modulated using a variator, thus making it possible to adjust the production of calories. under frost conditions, .sanQ burn vegetation.

 The connection of the wires between the rows can be done in series in the case of triangular or trapezoidal shaped plots, in parallel in the case of square or paralipipedal plots. Within the same row, the wires can be assembled in parallel.

 The shielding provided on the aforementioned monofilaments allows the positioning of these on the stakes without insulation problems. The same goes for the wires sheathed with P.V.C or polyethylene.

 The device according to the invention is therefore particularly suitable for protecting the vines against frost.

Claims (6)

CLAIMS 1) Method and device for implementing it making it possible to protect crops from frost by raising the temperature, characterized in that the heat producing device is a wire traversed by a low voltage electric current and d variable intensity by dimming (or any other suitable system) and allowing the temperature produced by the passage of current through the wire to be adjusted to the different types of jellies.  2) Characterized by the fact that the wire can play the role of trellising or lifting the vegetation for espalier crops (for vines or fruit trees or be placed near the sensitive areas of plants (open field crops in line ) not trellised by being fixed on retaining stakes  3) Characterized by the fact that the wire is made up of a core of nickel-chrome or nickel or "B.A.L.C.O" (registered trademark) or any other metal suitable for easy heating  4) Characterized by the fact that the core of the wire is surrounded by an insulator of the mineral or refractory type.  o) Characterized by the fact that the external part of the wire, the sheath is made of stainless steel, P.X / .C, Teflon (registered trademark) or any insulator resistant to corrosion and allowing to fix the wire or wires directly on the stakes.  6) Characterized by the fact that the triggering of the current flow in the wire can be controlled either manually or automatically by a thermostat.  7) Characterized by the fact that the supply voltage can be adjusted by a dimmer or dimmer.  8) Characterized by the fact that the supply is possible with alternating or direct current according to safety standards.