Weed control system by spraying a heated solution

Abstract

Weeding system (1) comprising: - a chassis shaped for coupling to a tractor; - an electric generator (3) mounted on the chassis and comprising a coupling member (30) for coupling with a power take-off (21) of the tractor in order to generate electrical power; - a storage tank (4) for containing a solution; - a spraying assembly (5) comprising a spraying line (50) in fluid communication with the storage tank and comprising a main pump (51) electrically powered by the electric generator and connected to spraying nozzles (59); - an electric heating device (6) electrically powered by the electric generator and in heat exchange with the spraying line in order to heat the solution before spraying to a spraying temperature of between 60 and 95 °C. Abstract figure: Figure 7

Description

Title of the invention: Weed control system by spraying a heated solution Technical field

[0001] The invention relates to a weeding system for a tractor, that is to say a weeding system designed to be coupled to a tractor in order to be towed over the area to be weeded.

[0002] The invention finds a preferred application for weeding agricultural plots, such as orchards, vineyards and crop fields, such as fields of hoed crops, such as for example beets. Prior art

[0003] As is well known, due to standards and prohibitions regarding the use of phytosanitary products, farmers resort to mechanical weeding solutions aimed at removing grasses and plants from the ground. However, these mechanized solutions are both restrictive and time-consuming, and therefore sometimes incompatible with the various obligations and constraints that these farmers bear.

[0004] Another solution consists of thermal weeding using a thermal burner, although there are risks of damage to nearby crops, not to mention the costs linked to the consumption of fossil energy to power the thermal burner. Summary of the invention

[0005] An aim of the invention is to propose a weeding system which is simple to use, consumes little energy, is efficient and respects the environment.

[0006] To this end, the invention proposes a weeding system for a tractor equipped with a power take-off, this weeding system comprising:

[0007] - a chassis provided with a coupling mechanism designed for coupling the chassis on the towing vehicle;

[0008] - an electric generator mounted on the chassis and comprising a member coupling designed for coupling with the power take-off of the towing vehicle in order to generate electrical power by driving the power take-off;

[0009] - a storage tank configured to contain a solution;

[0010] - a spray assembly comprising a spray line in fluid communication with the storage tank, said spray line comprising a main pump electrically powered by the generator electric and connected to one or more spray nozzles in order to spray the solution;

[0011] - an electric heating device electrically powered by the generator electrical and in heat exchange with the spray line in order to be able to heat the solution before spraying to a spraying temperature between 60 and 95°C.

[0012] Thus, the invention proposes to exploit the kinetic energy delivered by the power take-off of the tractor, in order to convert it into electrical power which will be used to power the heating and spraying of a solution. In other words, this weeding system makes it possible to combine a parameterized solution, possibly a natural additive and heating and spraying means; this weeding system makes it possible to raise the temperature of the solution and spray it on the ground in order to obtain a lethal effect on the weeds.

[0013] Thus, the farmer will be able to weed effectively, globally or locally, without resorting to phytosanitary products and mechanical weeding, thus promoting the preservation of soils, their fertility and the integrity of the root systems of crops.

[0014] In a first embodiment, the electric heating device comprises one or more electric heating resistors in heat exchange with the spray line.

[0015] The choice of heating by one or more electric heating resistors is advantageous for a rapid rise in temperature and a saving in weight and size. Indeed, the solution will be in contact, direct or indirect, with the electric heating resistor(s) to quickly rise in temperature.

[0016] Advantageously, the electric heating device comprises several successive electric heating resistors, arranged one after the other, so that the solution is heated by the several successive electric heating resistors, and the several electric heating resistors are controlled independently.

[0017] In this way, it is possible to adapt the heating of the different electrical heating resistors independently, in order to precisely control the heating of the solution to the desired temperature. For example, one or more resistors can be at their maximum heating, while one or more other resistors can be heated more or less, or even be switched off.

[0018] In a second embodiment, the electric heating device comprises: - a water tank; - a steam boiler electrically powered by the electric generator and connected to the water tank via a secondary pump electrically powered by the electric generator, to produce water vapor; - a heat exchanger connected to the boiler via a steam line and connected to the water tank via a return line, said heat exchanger being in heat exchange with the spray line.

[0019] The choice of heating by heat exchanger and steam boiler is advantageous for an efficient and controlled rise in temperature of the solution to the spraying temperature which is, as a reminder, between 60 and 95°C.

[0020] According to one possibility, a level sensor is provided in the steam boiler.

[0021] Such a level sensor makes it possible to control the filling of the steam boiler, in order to start it once a given filling level has been reached. Thus, before starting, the operator fills the water tank (which forms a feed tank) with water (preferably demineralized water). Then, the secondary pump fills the steam boiler to a given filling level, controlled by the level sensor. Once the required filling level has been reached, the steam boiler is gradually started and, once the water has been heated to 100°C, it is converted into steam and is conveyed to the heat exchanger to heat the solution by steam / liquid exchange. As it passes through the heat exchanger, the water vapor condenses and, by gravity or pumping, returns to the water tank. The water tank / boiler / heat exchanger circuit is therefore an independent closed circuit.

[0022] According to another possibility, the electric heating device comprises a control valve arranged on the steam line, between the steam boiler and the heat exchanger, to control a flow rate of steam at the outlet of the steam boiler.

[0023] This control valve, present on the path of the water vapor (at the outlet of the steam boiler) makes it possible to adjust the flow of steam sent to the heat exchanger, depending on the objective of increasing the temperature of the solution.

[0024] According to another possibility, the steam boiler comprises one or more electric heating resistors electrically powered by the electric generator.

[0025] Thus, once the required filling level has been reached in the steam boiler, the steam boiler is started by electrically supplying the electric heating resistor(s) present in the steam boiler.

[0026] According to one variant, the steam boiler comprises a pressure detector connected to an electrical cut-off unit which automatically cuts off the electrical supply when the pressure inside the steam boiler exceeds a given threshold, for example 8 bars.

[0027] According to another variant, the steam boiler comprises a safety valve which opens to discharge the steam outside the steam boiler in the event of malfunction or overpressure (for example a pressure greater than 10 bars).

[0028] In a particular embodiment, the spray line comprises a bypass device arranged between the electric heating device and the one or more spray nozzles, and the spray assembly comprises a return line connecting the bypass device and the storage tank, said bypass device being configurable between: - a shaped spray configuration for directing the solution exiting the electric heating device to the one or more spray nozzles, and - a shaped return configuration for returning the solution exiting the electric heating device to the storage tank via the return line.

[0029] Thus, depending on the configuration of the bypass device, the solution is sent to the one or more spray nozzles to be sprayed, or it returns to the storage tank to be heated again; which allows the solution to be heated gradually.

[0030] According to a first possibility, the bypass device comprises a main valve arranged on the spray line downstream of the return line, and a secondary valve arranged on the return line.

[0031] Thus, in the spray configuration, the main valve is open and the secondary valve is closed; and in the return configuration, the main valve is closed and the secondary valve is open.

[0032] According to a second possibility, the bypass device comprises a three-way valve, having an inlet on the spray line on the electric heating device side, a first outlet on the spray line on the spray nozzle(s) side, and a second outlet on the return line. Thus, in the spray configuration, the inlet is in communication with the first outlet; and in the return configuration, the inlet is in communication with the second outlet.

[0033] Advantageously, the weeding system comprises: - a first temperature sensor provided in the storage tank or on the spray line between the storage tank and the electric heating device or on the return line, to measure a first temperature which is a temperature of the solution in the storage tank or at the outlet of the storage tank or in the return line, and - a control / command unit connected to the electric heating device, to the bypass device and to the first temperature sensor, said control / command unit being configured to control a preheating phase in which said control / command unit: - controls the electric heating device to heat the solution until the first temperature is at a given preheating temperature, less than or equal to the spraying temperature; and - controls the bypass device in the return configuration.

[0034] Thus, the solution is gradually heated (during the preheating phase) while keeping the bypass device in its return configuration, until the first temperature reaches a given preheating temperature, less than or equal to the desired spraying temperature. Thus, the operator can preheat the solution, the time to reach the area to be weeded, before being able to spray the solution by controlling the bypass device to its spraying configuration; if necessary, when the operator controls the spraying, the electric heating device is also controlled to make the solution reach the spraying temperature.

[0035] According to one possibility, the weeding system comprises a second temperature sensor provided on the supply line between the electric heating device and the bypass device for measuring a second temperature which is an outlet temperature of the electric heating device, and the control / command unit is connected to the second temperature sensor and is configured to control a spraying phase in which said control / command unit: - controls the electric heating device to heat the solution so that the second temperature is at the spraying temperature; and - controls the bypass device in the spraying configuration; and the control / command unit is configured to authorize a transition from the preheating phase to the spraying phase when the first temperature has reached the preheating temperature.

[0036] Thus, the control / command unit authorizes spraying once the first temperature has reached the preheating temperature, and the operator can then give a spraying order so that the control / command unit controls the spraying phase, and in particular controls the bypass device in the spraying configuration and controls the electric heating device to heat the solution so that the second temperature is at the spraying temperature.

[0037] The preheating temperature is preferably lower than the spraying temperature, for example being between 40 and 60°C, so that the electric heating device is controlled at a given preheating power. Once this preheating temperature is reached and the control / command unit has entered the spraying phase, the electric heating device is controlled at a heating power sufficient to heat the solution at the outlet of the electric heating device to the spraying temperature (in starting from the preheating temperature reached during the preheating phase) and the bypass device is switched to the spray configuration.

[0038] According to one possibility, an upstream check valve is provided on the spray line, between the storage tank and the main pump, where this upstream check valve allows flow in one direction from the storage tank to the main pump (and therefore prohibits flow in an opposite direction, towards the storage tank).

[0039] This upstream non-return valve is advantageous for preventing a return in the spray line of the solution towards the storage tank.

[0040] According to another possibility, a downstream non-return valve is provided on the spray line, at the outlet of the electric heating device, where this downstream non-return valve allows flow in one direction from the electric heating device to the one or more spray nozzles (and therefore prohibits flow in an opposite direction, towards the electric heating device).

[0041] This downstream non-return valve prevents the solution from returning to the electric heating device, thus avoiding any risk of the solution boiling inside the electric heating device after the main pump has been stopped.

[0042] According to a first embodiment, the weeding system comprises at least one additive unit which comprises an additive tank containing an additive and connected to an injection device connected to the spray line to inject the additive at an injection point in the spray line.

[0043] Thus, an additive (or several additives) can be introduced or injected into the solution, so as to improve the efficiency, in addition to the thermal effect already provided by the spraying of the previously heated solution.

[0044] According to one characteristic, the injection point is arranged downstream of the electric heating device; so as to inject the additive after having heated the solution.

[0045] According to another characteristic, the injection point is arranged downstream of the bypass device.

[0046] Advantageously, a mixer is arranged on the spray line downstream of the injection point; in order to efficiently mix the additive with the solution, before spraying.

[0047] In a particular embodiment, a terminal check valve is provided on the spray line, between the bypass device and the injection point, where this terminal check valve allows flow in one direction from the bypass device to the injection point (and therefore prohibits flow in an opposite direction, towards the bypass device).

[0048] Thus, this terminal non-return valve prevents the additive from rising in the spray line towards the storage tank and the heating device. electrically, thereby blocking the additive downstream of this terminal check valve, between this terminal check valve and the spray nozzle(s).

[0049] According to a second embodiment, the weeding system does not include an additive unit, and the additive is introduced directly into the solution in the storage tank.

[0050] In an embodiment where several spray nozzles are provided, the weeding system may comprise, upstream of each of the spray nozzles, a main solenoid valve; which thus makes it possible to cut off the spraying on the corresponding spray nozzle.

[0051] Advantageously, the weeding system comprises a plurality of secondary return lines connecting the spray line to the return line, where each of the plurality of secondary return lines is associated with one of the spray nozzles and comprises a secondary solenoid valve followed by a calibration pellet which is calibrated to an output flow rate which is equivalent to a spray flow rate of the associated spray nozzle, said secondary solenoid valve being controlled in a synchronized and opposite manner relative to the main solenoid valve of the associated spray nozzle.

[0052] In this way, when one of the main solenoid valves is closed, so that the corresponding spray nozzle does not spray, then the portion of solution that is not sprayed by this spray nozzle returns to the storage tank via the corresponding secondary line because the secondary solenoid valve concerned is open (opposite the associated main solenoid valve). The advantage is that this portion of solution is returned with the same flow rate as the spray flow rate of the spray nozzle, thanks to the calibration tablet. This makes it possible to have no loss of flow rate in the circuit, despite the closure of one of the main solenoid valves, which is very advantageous because the regulation of the heating provided by the electric heating device depends on the flow rate of the solution, and it is therefore preferable to keep this flow rate stable for good management of the heating of the solution.

[0053] The invention also relates to a weeding method implementing the following steps: - provide a weed control system as described above; - fill the storage tank with a solution; - attach the chassis of the weeding system to a tractor equipped with a power take-off; - couple the coupling member of the electric generator with the power take-off of the towing vehicle; - start the main pump of the spray assembly and the electric heater to heat and spray the solution to a spraying temperature between 60 and 95°C.

[0054] The solution is then heated to between 60 and 95°C before being sprayed on the weeds. The targeted grasses and plants are then affected by a thermal shock which damages their chlorophyll parts, so that they can no longer initiate the photosynthesis process to live.

[0055] In an advantageous embodiment, the weeding method comprises a preheating phase in which the control / command unit: - controls the electric heater to heat the solution until the first temperature is at the given preheating temperature, less than or equal to the spraying temperature; and - controls the bypass device in the return configuration, so that the solution runs in a closed circuit at least until the first temperature reaches the preheating temperature.

[0056] Advantageously, the weeding method comprises a transition from the preheating phase to the spraying phase once the first temperature has reached the preheating temperature, where in the spraying phase the control / command unit: - controls the electric heating device to heat the solution so that the second temperature is at the spraying temperature; and - controls the bypass device in the spray configuration, so that the solution is sprayed at the spray temperature.

[0057] Thus, when switching from the preheating phase to the spraying phase, the bypass device switches to the spraying configuration and the control of the electric heating device is modified to be able, when the solution passes through the electric heating device, to heat this solution to the desired spraying temperature, by monitoring the second temperature (and no longer the first temperature compared to the preheating phase).

[0058] According to one possibility, in the preheating phase, when the first temperature has reached the preheating temperature, then an authorization signal is emitted on a man / machine interface to inform that the transition from the preheating phase to the spraying phase is authorized and possible by operating a spraying order on this man / machine interface.

[0059] Thus the operator initiates the preheating phase, and once the preheating is adequate (i.e. the first temperature has reached the preheating temperature), then this same operator is informed thanks to the authorization signal (which can be visual and / or audible) that he can, at his convenience, move into the spraying phase by operating a spraying order (for example by pressing a button or a key on a touch screen).

[0060] In a particular embodiment, the weeding method implements the following steps: - start the steam boiler and the secondary pump to produce water vapor; - heat the solution through the heat exchanger.

[0061] Advantageously, the weeding process comprises a step in which an additive is introduced into the solution before spraying.

[0062] According to a first embodiment, the additive is injected at an injection point in the spray line, by means of an additive unit which comprises an additive reservoir containing said additive and connected to an injection device connected to said injection point.

[0063] According to one characteristic, the injection point is arranged downstream of the electric heating device, so that the additive is introduced into the solution previously heated to the spraying temperature.

[0064] According to a second embodiment, the additive is introduced into the storage tank, so that the additive is introduced into the solution before being heated to the spraying temperature.

[0065] According to a first variant, the solution is an aqueous solution and the additive is a water-soluble zinc-based component.

[0066] According to one possibility, the zinc-based component is a zinc salt.

[0067] According to a second variant, the solution is an aqueous solution and the additive is a water-soluble fatty acid.

[0068] According to one possibility, the fatty acid is a potassium salt of fatty acid having a carbon chain length between C7 and C20.

[0069] According to a third variant, the solution is an aqueous solution and the additive is a water-soluble boron-based component.

[0070] To optimize the effect of weeding with a solution heated to the spraying temperature between 60 and 95°C, over time and to achieve a weeding duration of at least 30 days, it is advantageous to provide specific minerals when spraying the solution which accelerate the process of burning and / or asphyxiation of the grasses. In this respect, zinc, boron and fatty acids are particularly well suited for implementing the invention and achieving such results.

[0071] According to one characteristic, the solution is an aqueous solution based on water that has been previously filtered and softened to reduce its hardness.

[0072] According to another characteristic, the solution has an acidic pH, and for example a pH between 1 and 6, and for example between 2 and 4.

[0073] According to another characteristic, the solution has a conductivity of between 1 and 20 qS / cm, and for example between 2 and 10 qS / cm.

[0074] These characteristics are all advantageous for promoting the weeding effect and the weeding duration. Brief description of the drawings

[0075] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of non-limiting examples of implementation, made with reference to the appended figures in which:

[0076] [Fig-1] is a schematic view of a weeding system mounted on a machine tractor, in a variant with the spray nozzles mounted at the rear of the towing vehicle;

[0077] [Fig.2] is a zoomed-in schematic view of the chassis of the weeding system of [Fig.l];

[0078] [Fig.3] is another zoomed-in schematic view of the chassis of the weeding system of [Fig.l];

[0079] [Fig.4] is a schematic view of another weeding system mounted on a tractor, in a variant with the spray nozzles mounted at the front of the tractor;

[0080] [Fig.5] is a zoomed-in schematic view of the chassis of the weeding system of [Fig.4];

[0081] [Fig.6] is a zoomed-in schematic view of the bracket mounted at the front of the tractor unit as part of the weeding system of [Fig.4];

[0082] [Fig.7] is a schematic and functional view of the weeding system of Figures 1 and 4.

[0083] [Detailed description of embodiments of the invention]

[0084] With reference to the Figures, a weeding system 1 is provided to be coupled to a tractor 2, such as an agricultural tractor, which is provided with a hitch 20, such as for example a three-point hitch, and a power take-off 21, also known as a power take-off, which is a mechanical system for transmitting the torque of an engine of the tractor 2 to a shaft, and generally a splined shaft. In the example illustrated, the hitch 20 and the power take-off 21 are at the rear of the tractor 2.

[0085] This weeding system 1 comprises a chassis 10 provided with a coupling mechanism 11 designed for coupling or attachment of the chassis 10 to the coupling. 20 of the tractor unit 2. Thus, in the example illustrated, the chassis 10 is at the rear of the tractor unit 2.

[0086] The weeding system 1 comprises an electric generator 3 mounted on the chassis 10 and comprising a coupling member 30 shaped for coupling with the power take-off 21 of the tractor machine 2 in order to generate electric power by driving the power take-off 21.

[0087] The weeding system 1 comprises an electrical cabinet 31 equipped with electrical components, and in particular safety components, which is electrically connected to the electrical generator 3 and which forms a relay for electrically supplying various electrical elements of the weeding system 1, as described later.

[0088] The weeding system 1 comprises a man / machine interface 33, such as for example a screen and / or a control panel, in order to allow an operator, such as for example the driver of the tractor 2, to make his selections, enter commands, view the selected operations and / or the operations in progress, view parameters such as a temperature, a pressure, a flow rate, etc. This man / machine interface 33 is preferably arranged in the cabin 24 of the tractor 2.

[0089] The weeding system 1 also comprises a control / command unit 32, comprising for example at least one automaton and / or an electronic card and / or a processor, which controls the electrical elements of the weeding system 1, as described later. This control / command unit 32 can be arranged in the electrical cabinet 31, and it is connected (wired or wireless) to the human / machine interface 33.

[0090] The weeding system 1 comprises a storage tank 4 configured to contain a solution. The storage tank 4 is mounted on a rolling chassis 40 which is coupled to the chassis 10, at the rear of this chassis 10, for example by means of a drawbar.

[0091] Advantageously, the solution is an aqueous solution based on water that has been previously filtered and softened to reduce its hardness, the pH of which has been adjusted to be acidic, and in particular to be between 1 and 6, and for example between 2 and 4, and which has a conductivity of between 1 and 20 qS / cm, and for example between 2 and 10 qS / cm.

[0092] Advantageously, an additive (or adjuvant) is added to this solution to improve weed control. Three examples of additives are given below: - a first additive is a water-soluble zinc-based component, such as a zinc salt; - a second additive is a water-soluble fatty acid, such as for example a potassium salt of a fatty acid having a carbon chain length between C7 and C20; - a third additive is a water-soluble boron-based component, such as an acidic solution of a trace element based on boron and molybdenum.

[0093] In the example illustrated, the additive is introduced downstream of the storage tank 4, but in a variant the additive can be introduced directly into the solution in the storage tank 4.

[0094] The weeding system 1 comprises a spraying assembly 5 comprising a spraying line 50 in fluid communication with the storage tank 4. The spraying line 50 comprises a main electric pump 51 which is electrically powered by the electric generator 3, via the electrical cabinet 31. This spraying line 50 ends with spraying nozzles 59 in order to spray the solution onto the ground to be weeded, during the advance of the tractor 2. In the example illustrated, the spraying nozzles 59 are two in number and are arranged symmetrically on the right and on the left.

[0095] Thus, the spray line 50 of the spray assembly 5 comprises a spray pipe 500 connecting the storage tank 4 to the spray nozzles 59 and on which the main pump 51 is placed to pump the solution from the storage tank 4 to the spray nozzles 59.

[0096] The control / command unit 32 is connected to the main pump 51 to control the main pump 51 in order to obtain a flow rate of the solution in accordance with a flow rate objective of the spray nozzles 59 at the outlet.

[0097] The weeding system 1 comprises an electric heating device 6 electrically powered by the electric generator 3, via the electrical cabinet 31. This electric heating device 6 is in heat exchange with the spraying line 50 (in other words with the spraying pipe 500) in order to be able to heat the solution before spraying to a spraying temperature TP of between 60 and 95°C.

[0098] In the example illustrated, the electric heating device 6 comprises several successive electric heating resistors 60 (arranged one after the other) which are in heat exchange with the spray line 50. Each electric heating resistor 60 is surrounded by a heating body 61 inside which the solution circulates. Thus the spray line 500 successively connects the heating bodies 61 so that the solution is heated by heat exchange with the successive electric heating resistors 60.

[0099] These electric heating resistors 60 are electrically powered by the electric generator 3, via the electrical cabinet 31. These heating resistors The electric heating resistors 60 are independently controlled by the control / command unit 32, so that this control / command unit 32 can independently adapt the heating power of each of the electric heating resistors 60, in order to meet the desired temperature objective.

[0100] In the embodiment of Figures 1 to 3, the spray nozzles 59 are mounted on the chassis 10, and more precisely below the chassis 10. The electric heating device 6 and its electric heating resistors 60 are mounted on a support 13, which is mounted on the chassis 10, and more precisely above the chassis 10. Thus, the spray nozzles 59 and the electric heating device 6 are at the rear of the tractor 2.

[0101] In the embodiment of Figures 4 to 6, the spray nozzles 59 are mounted on the support 13 which is this time fixed to the front of the tractor 2. The electric heating device 6 and its electric heating resistors 60 are also mounted on this support 13. Thus, the spray nozzles 59 and the electric heating device 6 are at the front of the tractor 2 in this embodiment of Figures 4 to 6.

[0102] The chassis 10 thus forms an energy functional block, because it contains the electric generator 3 which provides the energy for the operation of the spraying system 1. The support 13 forms an applicator functional block, because it contains the electric heating device 6, as well as the electrical cabinet 31 and the hydraulic equipment described below (bypass device 52, non-return valves, injection device 91). The support 13 is designed to be able to be stacked or mounted on the chassis 10 in order to be at the rear of the tractor 2 (embodiment of Figures 1 to 3), and also to be able to be hooked onto the front of the tractor 2 (embodiment of Figures 4 to 6). These two functional blocks can thus be stackable or be dissociated, thus making it possible to envisage other arrangements, as could be the case on a tractor of the vine straddle type.

[0103] It should be noted that the chassis 10 and the support 13 can each be closed by means of walls which thus form casings protecting the various functional members which they support.

[0104] The spray line 50 comprises a bypass device 52 arranged between the electric heating device 6 and the spray nozzles 59. In other words, this bypass device 52 is placed at the outlet of the electric heating device 6, after the last of the electric heating resistors 60.

[0105] The spray assembly 5 comprises a return line 53 (or a return conduit) connecting the diversion device 52 and the storage tank 4. Thus, the diversion device 52 has the function of directing the solution, at the outlet of the device electric heating 6, either towards the spray nozzles 59 or towards the storage tank 4 via the return line 53. In other words, the diversion device 52 makes it possible to divert the solution to return to the storage tank 4.

[0106] In the example illustrated in [Fig.7], the bypass device 52 comprises a main valve 520 arranged on the spray line 50 downstream of the return line 53, and a secondary valve 521 arranged on the return line 53; the main valve 520 and the secondary valve 521 may be solenoid valves or controlled valves. In a variant not illustrated, the bypass device 52 is a three-way valve comprising an inlet in communication with the outlet of the electric heating device 6, a first outlet connected to the spray nozzles 59 and a second outlet connected to the storage tank 4 via the return line 53.

[0107] This bypass device 52 is configurable between: - a spray configuration shaped to direct the solution leaving the electric heating device 6 towards the spray nozzles 59, and in which the main valve 520 is open and the secondary valve 521 is closed (or in the “three-way valve” variant, the first outlet of the three-way valve is open and the second outlet is closed); and - a return configuration designed to return the solution at the outlet of the electric heating device 6 to the storage tank 4 via the return line 53, and in which the main valve 520 is closed and the secondary valve 521 is open (or in the “three-way valve” variant, the first outlet of the three-way valve is closed and the second outlet is open).

[0108] A first temperature sensor 80 is provided in the storage tank 4 to measure a first temperature T1 which is a temperature of the solution in the storage tank 4. Alternatively, this first temperature sensor 80 is placed at the outlet of the storage tank 4, or is placed on the return line 53 (therefore at the inlet of the storage tank 4), so that the first temperature corresponds to the temperature of the solution at the outlet of the storage tank or in the return line 53; all these temperatures being relatively equivalent and representative of the temperature of the solution in the storage tank 4.

[0109] A second temperature sensor 81 is provided on the spray line 50 at the outlet of the electric heating device 6, between the electric heating device 6 and the bypass device 52 to measure a second temperature T2 which is a temperature of the solution at the outlet of the electric heating device 6. Alternatively, this second temperature sensor 81 can be positioned on the spray line 50 downstream of the bypass device 52.

[0110] The control / command unit 32 is connected: - to the electric heating device 6 in order to be able to control a heating power applied to the solution and thus adjust the temperature of the solution; - to the bypass device 52 in order to be able to control its configuration between the return configuration and the spray configuration; and - to the first temperature sensor 80 and to the second temperature sensor 81 in order to be able to control the electric heating device 6 and the bypass device 52 as a function of the first temperature T1 during a preheating phase, and as a function of the second temperature T2 during a spraying phase.

[0111] More precisely, the control / command unit 32 can implement a preheating phase in which the control / command unit 32: - controls the electric heating device 6 to heat the solution according to the first temperature Tl, until this first temperature Tl is equal to a given preheating temperature TC, which is lower than the spraying temperature TP; and - controls the bypass device 52 in the return configuration.

[0112] Thus, in this preheating phase, the bypass device 52 is in its return configuration at least as long as the first temperature T1 is lower than the preheating temperature TC, so that the solution rotates in a closed circuit during this preheating phase, then the bypass device 52 can be controlled towards the spraying configuration when the first temperature T1 reaches the preheating temperature TC.

[0113] The control / command unit 32 is further configured to authorize a transition from the preheating phase to the spraying phase once the first temperature T1 has reached the preheating temperature TC. More precisely, in the preheating phase, when the first temperature T1 has reached the preheating temperature TC, then an authorization signal is emitted on the human / machine interface 33 to inform the operator that the transition from the preheating phase to the spraying phase is authorized and possible by operating a spraying order on this human / machine interface 33, for example by pressing a button or a key on a touch screen.

[0114] When this spraying order is carried out, the control / command unit 32 enters the spraying phase, in which it: - controls the electric heating device 6 to heat the solution so that the second temperature T2 is at the spraying temperature TP; and - controls the bypass device 52 in the spray configuration, so that the solution is sprayed at the spray temperature TP.

[0115] In the spraying phase, the control / command unit 32 regulates the different electric heating resistors 60 to stabilize the second temperature T2 at the spraying temperature TP.

[0116] It should be noted that the preheating phase is initiated at startup, for example through an input made on the human / machine interface 33. This preheating of the solution is advantageous in order not to demand a large amount of energy from the tractor 2 at once. Thanks to this preheating phase, the components of the tractor 2 are spared and the operator can drive to the plot to be weeded while the solution is preheated until it reaches the desired preheating temperature TC so that the weeding system 1 is operational for the spraying phase which will follow.

[0117] During the preheating phase, the control / command unit 32 can control the main pump 51 to run at full speed in order to pump the solution contained in the storage tank 4 and send it to the electric heating device 6 at a maximum possible flow rate for the most optimized preheating time possible. The solution then passes through the electric heating resistors 60 in series, and the bypass device 52 is in its return configuration as described above.

[0118] A flow sensor 82 is provided on the spray line 50, between the main pump 51 and the electric heating device 6 to measure a flow rate D of the solution at the inlet of the electric heating device 6. This flow sensor 82 makes it possible to know the flow rate D which can thus be taken into consideration by the control / command unit 32 to regulate the electric heating device 6, and in particular to regulate the various electric heating resistors 60. This flow sensor 82 also makes it possible to set up a safety system for cutting off the electric heating device 6 if the flow rate D is below a given low threshold, for example in the case where the storage tank 4 is empty.

[0119] A pressure sensor 83 is provided on the spray line 50 at the outlet of the electric heating device 6, between the electric heating device 6 and the bypass device 52 to measure a pressure P of the solution at the outlet of the electric heating device 6.

[0120] Two non-return valves may be provided on the spray line 50, namely: - an upstream non-return valve 54 arranged between the storage tank 4 and the main pump 51, where this upstream non-return valve 54 allows flow in one direction from the storage tank 4 to the main pump 51 and therefore prohibits flow in an opposite direction, towards the storage tank 4; and - a downstream non-return valve 55 arranged at the outlet of the electric heating device 6, between the electric heating device 6 and the bypass device 52, where this downstream check valve 55 allows flow in one direction from the electric heating device 6 to the spray nozzles 59, and therefore prohibits flow in an opposite direction, towards the electric heating device 6.

[0121] It is possible to have a non-return valve 530 on the return line 53, where this non-return valve 530 allows flow in one direction from the bypass device 52 to the storage tank 4, and therefore prohibits flow in an opposite direction, towards the bypass device 52; making it possible to secure the direction of flow in the return line 53.

[0122] As illustrated in [Fig.7], it is possible to have a manual outlet valve 41 which is arranged at the outlet of the storage tank 4 at the start of the spraying line 50; this manual outlet valve 41 is thus arranged between the storage tank 4 and the main pump 51. This manual outlet valve 41 can thus be closed when the weeding system 1 is stopped, for example to prevent the solution present in the storage tank 4 from flowing by gravity towards the electric heating device 6.

[0123] A manual inlet valve 42 may be arranged at the inlet of the storage tank 4 at the end of the return line 53.

[0124] The weeding system 1 comprises an additive unit 9 which comprises an additive reservoir 90 containing the additive that the operator wishes to add to the solution, where this additive reservoir 90 is connected to an injection device 91, for example of the metering pump type, connected to the spray line 50 to inject the additive at an injection point 92 in the spray line 50.

[0125] The injection device 91 is electrically powered by the electric generator 3, via the electrical cabinet 31. The control / command unit 32 is connected to the injection device 91 and to the flow sensor 82 and is configured to control the injection device 91 as a function of the flow rate D of the solution measured by the flow sensor 82 at the outlet of the electric heating device 6.

[0126] Thus the control / command unit 32 can dose the injection rate of the additive into the solution as a function of the flow rate D of the solution, so as to adjust the concentration of the additive in the solution. This concentration can for example be entered by the operator on the human-machine interface 33.

[0127] The injection point 92 is advantageously arranged downstream of the electric heating device 6, and preferably downstream of the bypass device 52, so that the solution is at the desired spraying temperature TP at the injection point 92.

[0128] It is advantageous to provide a terminal check valve 57 on the spray line 50, between the bypass device 52 and the injection point 92, where this terminal check valve 57 allows flow in one direction from the device bypass 52 to the injection point 92, and therefore prohibits flow in an opposite direction, towards the bypass device 52. The advantage of such a terminal non-return valve 57 is to prevent a return of additive to the storage tank 4 and to the electric heating device 6 and the main pump 51.

[0129] The weeding system 1 also comprises a mixer 93 arranged on the spray line 50 downstream of the injection point 92, between the injection point 92 and the spray nozzles 59, in order to homogenize the solution before exiting to the spray nozzles 59. This mixer 93 may be an electric mixer powered electrically by the electric generator 3, via the electrical cabinet 31. Alternatively, the mixer 93 is a mechanical mixer equipped with a propeller which rotates with the flow of solution passing through this mixer 93.

[0130] The weeding system 1 comprises, upstream of each of the spray nozzles 59, a main solenoid valve 58, i.e. one main solenoid valve 58 per spray nozzle 59. The control / command unit 32 is connected to each of the main solenoid valves 58 and is configured to control the opening and closing of these main solenoid valves 58 according to a selection made by the operator on the human-machine interface 33, who can thus select spraying on all or part of the spray nozzles 59. In other words, the operator can, at any time, using a command on the human-machine interface 33, cut off the spraying on one or other of the spray nozzles 59. The main solenoid valves 58 present upstream of the spray nozzles 59 will be open or closed according to the selection made by the operator.

[0131] The weeding system 1 also comprises, between the bypass device 52 and the injection point 92, secondary return lines 56 connecting the spray line 50 to the return line 53, where each of the several secondary return lines 56 is associated with one of the spray nozzles 59 and therefore with one of the main solenoid valves 58. There is therefore one secondary return line 56 per main solenoid valve 58 (and therefore per spray nozzle 59).

[0132] A secondary solenoid valve 560 is placed on each of the secondary return lines 56 and is followed by a calibration pellet 561 which is calibrated to an output flow rate which is equivalent to a spray flow rate of the associated spray nozzle 59; in other words, the output flow rate, at the outlet of this calibration pellet 561, is equivalent to the spray flow rate, at the outlet of the associated spray nozzle 59. Thus, each of the main solenoid valves 58 is associated with one of the secondary solenoid valves 560; so as to form main solenoid valve 58 / secondary solenoid valve 560 pairs.

[0133] Each secondary solenoid valve 560 is controlled in a synchronized and opposite (or inverted) manner relative to the main solenoid valve 58 which is connected to it. associated; in other words when the main solenoid valve 58 is closed (to cut off the spraying on the corresponding spray nozzle 59), then the secondary solenoid valve 560 is open, and conversely when the main solenoid valve 58 is open (to allow spraying on the corresponding spray nozzle 59), then the secondary solenoid valve 560 is closed.

[0134] Thus, when the main solenoid valve 58 is closed then the corresponding spray nozzle 59 does not spray, and therefore the secondary solenoid valve 560 opens in order to allow the return to the storage tank 4 of the portion of unsprayed solution at a return flow rate corresponding to the spray flow rate of the spray nozzle 59 thanks to the prior calibration of the calibration tablet 561, thus making it possible to remain at a permanently stable flow rate in the circuit in order to maintain constant heating, in other words without loss of flow rate. Maintaining a stable flow rate is important for controlling the temperature regulation of the solution during the spraying phase.

[0135] The secondary solenoid valve 560 is placed upstream of the injection point 92, and even upstream of the terminal non-return valve 57, which allows a return to the storage tank 4 without the presence of an additive.

[0136] If all the main solenoid valves 58 are closed, because the operator pauses the spraying (for example to perform a maneuver of the tractor 2, such as a turn at the end of a row), then the solution returns to the storage tank 4 for the duration of this pause via the secondary return lines 56, through the different secondary solenoid valves 560 and the different calibration pellets 561, without there being any loss of flow rate or temperature when the main solenoid valves 58 are reopened when spraying is restarted.

Claims

Claims

1. Weeding system (1) for a tractor (2) provided with a power take-off (21), said weeding system (1) comprising: - a chassis (10) provided with a coupling mechanism (11) shaped for coupling the chassis (10) to the tractor; - an electric generator (3) mounted on the chassis (10) and comprising a coupling member (30) shaped for coupling with the power take-off (21) of the tractor (2) in order to generate electrical power by driving the power take-off (21); - a storage tank (4) configured to contain a solution; - a spray assembly (5) comprising a spray line (50) in fluid communication with the storage tank (4), said spray line (50) comprising a main pump (51) electrically powered by the electric generator (3) and connected to one or more spray nozzles (59) in order to spray the solution;- an electric heating device (6) electrically powered by the electric generator (3) and in heat exchange with the spray line (50) in order to be able to heat the solution before spraying to a spraying temperature (TP) between 60 and 95°C.;

2. Weeding system (1) according to claim 1, wherein the electric heating device (6) comprises one or more electric heating resistors (60) in heat exchange with the spray line (50).

3. Weeding system (1) according to claim 2, wherein the electric heating device (6) comprises several successive electric heating resistors (60), arranged one after the other, so that the solution is heated by the several successive electric heating resistors (60), and the several electric heating resistors (60) are controlled independently.

4. Weeding system (1) according to claim 1, wherein the electric heating device comprises: - a water tank; - a steam boiler electrically powered by the electric generator (3) and connected to the water tank via a secondary pump electrically powered by the electric generator (3), to produce water vapor; - a heat exchanger connected to the boiler via a steam line and connected to the water tank via a return line, said heat exchanger being in heat exchange with the spray line (50).

5. Weeding system (1) according to any one of the preceding claims, wherein the spray line (50) comprises a bypass device (52) arranged between the electric heating device (6) and the one or more spray nozzles (59), and the spray assembly (5) comprises a return line (53) connecting the bypass device (52) and the storage tank (4), said bypass device (52) being configurable between: - a spray configuration shaped to direct the solution leaving the electric heating device to the one or more spray nozzles (59), and - a return configuration shaped to return the solution leaving the electric heating device to the storage tank (4) via the return line (53).

6. Weeding system (1) according to claim 5, comprising: - a first temperature sensor (80) provided in the storage tank (4) or on the spray line (50) between the storage tank (4) and the electric heating device (6) or on the return line (53), for measuring a first temperature (Tl) which is a temperature of the solution in the storage tank (4) or at the outlet of the storage tank (4) or in the return line (53), and - a control / command unit (32) connected to the electric heating device (6), to the bypass device (52) and to the first temperature sensor (80), said control / command unit (32) being configured to control a preheating phase in which said control / command unit (32): - controls the electric heating device (6) to heat the solution until the first temperature (Tl) is at a preheating temperature (TC) given,less than or equal to the spraying temperature (TP); and, - controls the bypass device (52) in the return configuration.

7. Weeding system (1) according to claim 6, comprising a second temperature sensor (81) provided on the supply line (50) between the electric heating device (6) and the bypass device (52) for measuring a second temperature (T2) which is an outlet temperature of the electric heating device (6), and the control / command unit (32) is connected to the second temperature sensor (81) and is configured to control a spraying phase in which said control / command unit (32): - controls the electric heating device (6) to heat the solution so that the second temperature (T2) is at the spraying temperature (TP); and - controls the bypass device (52) in the spraying configuration;and the control / command unit (32) is configured to authorize a transition from the preheating phase to the spraying phase when the first temperature (Tl) has reached the preheating temperature (TC).;

8. A weeding system (1) according to any preceding claim, wherein an upstream non-return valve (54) is provided on the spray line (50), between the storage tank (4) and the main pump (51), wherein this upstream non-return valve (54) allows flow in one direction from the storage tank (4) to the main pump (51).

9. Weeding system (1) according to any one of the preceding claims, wherein a downstream non-return valve (55) is provided on the spray line (50), at the outlet of the electric heating device (6), where this downstream non-return valve (55) allows a flow in one direction from the electric heating device (6) towards the one or more spray nozzles (59).

10. A weed control system (1) according to any preceding claim, comprising at least one additive unit (9) which comprises an additive tank (90) containing an additive and connected to an injection device (91) connected to the spray line (50) for injecting the additive at an injection point (92) in the spray line (50).

11. Weeding system (1) according to claim 10, wherein the injection point (92) is arranged downstream of the electric heating device (6).

12. Weed control system (1) according to claims 5 and 11, wherein the injection point (92) is arranged downstream of the bypass device (52).

13. A weed control system (1) according to claim 12, comprising a terminal check valve (57) on the spray line (50), between the bypass device (52) and the injection point (92), wherein this terminal check valve (57) allows flow in one direction from the bypass device (52) to the injection point (92).

14. Weed control system (1) according to any one of claims 10 to 13, comprising a mixer (93) arranged on the spray line (50) downstream of the injection point (92).

15. A weeding system (1) according to any preceding claim, wherein a plurality of spray nozzles (59) are provided and the weeding system (1) comprises, upstream of each of the spray nozzles (59), a main solenoid valve (58).

16. A weeding system (1) according to claims 5 and 15, comprising a plurality of secondary return lines (56) connecting the spray line (50) to the return line (53), wherein each of the plurality of secondary return lines (56) is associated with one of the spray nozzles (59) and comprises a secondary solenoid valve (560) followed by a calibration pellet (561) which is calibrated to the spray flow rate of the associated spray nozzle (59), said secondary solenoid valve (560) being controlled in a synchronized and opposite manner relative to the main solenoid valve (58) of the associated spray nozzle (59).

17. A weeding method implementing the following steps: - providing a weeding system (1) according to any one of the preceding claims; - filling the storage tank (4) with a solution; - coupling the chassis (10) of the weeding system (1) to a tractor (2) provided with a power take-off (21); - coupling the coupling member (30) of the electric generator (3) with the power take-off (21) of the tractor (2); - starting the main pump (51) of the spray assembly (5) and the electric heating device (6) to heat and spray the solution to a spraying temperature (TP) between 60 and 95°C.

18. A weeding method according to claim 17, wherein the weeding system (1) is in accordance with claim 6 and the weeding method comprises a preheating phase in which the control / command unit (32): - controls the electric heating device (6) to heat the solution until the first temperature (Tl) is at the given preheating temperature (TC), less than or equal to the spraying temperature (TP); and - controls the bypass device (52) in the return configuration, so that the solution runs in a closed circuit at least until the first temperature (Tl) reaches the preheating temperature (TC).

19. A weeding method according to claim 18, wherein the weeding system (1) is according to claim 7 and the weeding method comprises a transition from the preheating phase to the spraying phase once the first temperature (T1) has reached the preheating temperature (TC), wherein in the spraying phase the control / command unit (32): - controls the electric heating device (6) to heat the solution so that the second temperature (T2) is at the spraying temperature (TP); and - controls the bypass device (52) in the spraying configuration, so that the solution is sprayed at the spraying temperature (TP).

20. Weeding method according to claim 19, wherein, in the preheating phase, when the first temperature (Tl) has reached the preheating temperature (TC), then an authorization signal is emitted on a man / machine interface (33) to inform that the transition from the preheating phase to the spraying phase is authorized and possible by operating a spraying order on this man / machine interface (33).

21. A weed control method according to any one of claims 17 to 20, wherein an additive is introduced into the solution before spraying.

22. A weed control method according to claim 21, wherein the additive is injected at an injection point (92) in the spray line (50), by means of an additive unit (9) which comprises an additive reservoir (90) containing said additive and connected to an injection device (91) connected to said injection point (92).

23. A weed control method according to claim 21, wherein the additive is introduced into the storage tank (4), such that the additive is introduced into the solution before being heated to the spraying temperature (TP).

24. A weed control method according to any one of claims 21 to 23, wherein the solution is an aqueous solution and the additive is a water-soluble zinc-based component.

25. A weed control method according to claim 24, wherein the zinc component is a zinc salt.

26. A weed control method according to any one of claims 21 to 23, wherein the solution is an aqueous solution and the additive is a water-soluble fatty acid.

27. A weed control method according to claim 26, wherein the fatty acid is a potassium salt of a fatty acid having a carbon chain length of between C7 and C20.

28. A weed control method according to any one of claims 21 to 23, wherein the solution is an aqueous solution and the additive is a water-soluble boron-based component.

29. A weed control method according to any one of claims 17 to 28, wherein the solution is an aqueous solution based on water which has been previously filtered and softened to reduce its hardness.

30. A weed control method according to any one of claims 17 to 29, wherein the solution has an acidic pH, and for example a pH of between 1 and 6, and for example of between 2 and 4.

31. A weeding method according to any one of claims 17 to 30, wherein the solution has a conductivity of between 1 and 20 qS / cm, and for example between 2 and 10 qS / cm.

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