FR3009925A1 - LIQUID SUPPLY CIRCUIT FOR SPRAY RAMP, CORRESPONDING DEVICE AND METHOD - Google Patents

Abstract

The present invention relates to a liquid supply circuit (2) for at least one spray boom (4) comprising a pipe (6), at least one nozzle (12) mounted on the pipe (6) and comprising closure (16) for stopping supply of said nozzle when the pressure of the liquid is less than or equal to a first predetermined pressure, and pressure reducing means (14). The supply circuit (2) comprises a liquid supply at a pressure higher than the first determined pressure, and a control means (28) configured to connect, in a first state, the supply of liquid at a first end ( 8) of the pipe to allow spraying of the liquid by said at least one nozzle (12), and configured to connect, in a second state, the supply of liquid to a second end (10) of the pipe so as to stopping the spraying of the liquid by said at least one nozzle (12). The invention also relates to a spraying device (1) and the corresponding methods.

Description

BACKGROUND OF THE INVENTION The present invention relates to spraying devices, especially those used in agriculture and can be of the towed or carried type. More particularly, the present invention relates to the process liquid supply circuits for the spray device ramps. In this type of device, each of the ramps is usually provided with one or more spray pipes comprising a plurality of spray nozzles distributed over the length of each pipe, the nozzles being possibly interchangeable, for example by barrel-type means. . The process liquid is usually taken by a pump into a storage tank and fed into each of the spray lines through a supply line.

When the treatment liquid, or "slurry", comprises solid elements in suspension at high concentration, it may tend to settle inside the pipes, in particular between a supply valve of the ramp and the nozzles where it can to be imprisoned. However, such a deposit causes, more or less rapidly depending on the nature of the treatment liquid, the partial or total obstruction of the ramps or nozzles, forcing the user to perform a complete disassembly for cleaning. It is thus known, when it is desired to stop the spraying of the treatment liquid by the nozzles, to maintain a circulation of the treatment liquid in the ramps but at a pressure lower than that of the opening of the nozzles (a process known as "Continuous circulation") or by closing all the nozzles of the ramp with individual closure means, for example tires. However, in the first case, there is a closing time of the nozzles still too long compared to the set point, with a release of droplets of treatment liquid, which is to be avoided. In the second case, the mounting and maintenance of the individual closure means involve a significant additional cost for the device, with a high frequency of malfunctions due to the number of closing means to be controlled.

OBJECT AND SUMMARY OF THE INVENTION The present invention aims at solving the various technical problems mentioned above. In particular, the present invention aims at providing a device, and the associated method, for rapidly stopping the spraying of a treatment liquid by a spray boom, while limiting the formation of deposit inside the spray liquid. this. The present invention also aims to provide a simple and robust device, to limit breakdowns and repairs. Thus, in one aspect, there is provided a liquid supply circuit for at least one spray boom, said spray boom comprising: - a pipe with a first end and a second end; - At least one nozzle mounted between the first and the second end and comprising closing means for stopping the supply of said nozzle when the pressure of the liquid in the nozzle is less than or equal to a first predetermined pressure; and a pressure reduction means mounted between said at least one nozzle and the second end. The supply circuit also comprises: a supply of liquid at a pressure greater than the first determined pressure; and control means configured to connect, in a first state, the supply of liquid to the first end in order to allow the spraying of the liquid by said at least one nozzle, and configured to connect, in a second state, the supplying liquid to the second end in order to stop the spraying of the liquid by said at least one nozzle.

Thus, alternately connect each end of the spray boom to the liquid supply provides in it the desired pressure to spray the treatment liquid, or to stop the spray. In particular, changing the supply of liquid to connect it to the second end makes it possible to obtain a rapid pressure variation in the spray boom, notably leading to the rapid closure of the closure means associated with each nozzle, while allowing a continuous circulation of the liquid in said ramp. The closure of the nozzles can thus be controlled in a global manner, without individual pneumatic means: a device is obtained that is faster, easier to manufacture, cheaper and more robust.

In addition, the sudden change in pressure in the ramp also makes it possible to take off any deposits that would have formed inside and drive them towards the second end. The closure means may be a calibrated valve, preferably by an elastic means, for example a spring. The calibrated valve makes it possible to control the supply of the nozzle associated with it, without requiring external control as is the case for the pneumatic valves. This gives a reliable and robust device over time. Preferably, the pressure reducing means is adapted to supply, from the liquid supply, a liquid at a pressure less than or equal to the first determined pressure. The pressure reducing means may be a throttle (or pellet) leading to a difference between the upstream pressure and the pressure downstream of the pressure reducing means. The pressure reducing means may also be a pipe whose diameter leads, due to the friction forces, to a pressure drop, i.e. a decrease in pressure, between the inlet and the outlet of the pipe. Preferably, the circuit also comprises a return line comprising an input and an output. In the first state, the control means is configured to connect the second end to the inlet of the return line, and in the second state, the first end to the inlet of the return line. The return line thus makes it possible to convey the treatment liquid to a reservoir, for example the supply reservoir, during the spraying and the spray-off phases, that is to say during the implementation. continuous traffic. Preferably, the control means comprises a four-way valve configured: - to connect, in the first state, the liquid supply and the first end on the one hand, and the second end and the inlet of the return pipe d 'somewhere else ; and - to connect, in the second state, the liquid supply and the second end on the one hand, and the first end and the inlet of the return pipe on the other. The use of a single valve (four-way) to connect together the different lines simplifies the device and thus to make it more robust. Preferably, the four-way valve comprises: a frame; a first collector connected to the liquid supply and passing through the frame; a second collector connected to the inlet of the return pipe and passing through the frame, parallel to the first collector; a first connection intended to be connected to the first end; a second connection intended to be connected to the second end; and a selection means adapted to make each of the collectors communicate with one of the two connections. With the first and second collectors passing through the frame, it is possible to easily mount several four-way valves in series on the liquid supply and the return line. The selection means may comprise: two pipes disposed in the plane of the two collectors, perpendicular to the collectors, the two pipes being mounted between the two collectors, along the same axis, and each communicating via a first end with one of the two collectors; collectors, and by a second end with a rotary means; and two elbows, each comprising a first portion in the plane of the collectors, parallel to the collectors, and a second portion perpendicular to the plane of the collectors, the elbows each connecting the rotary means with one of the two connections. Preferably, the liquid supply comprises a liquid reservoir, a pump mounted at the outlet of the reservoir and configured to supply the liquid at a pressure greater than the first determined pressure, and possibly a means for regulating the feed rate and / or a filter.

Preferably, the outlet of the return pipe is mounted upstream of the liquid reservoir. Thus, the liquid flowing in the spray boom and routed to the return line returns directly into the supply tank and can be reused later.

According to another aspect, the invention also relates to a spraying device comprising a spray boom, said spray bar comprising a pipe with a first end and a second end, at least one nozzle mounted between the first and the second end and comprising each a closure means for stopping the supply of said nozzle when the pressure of the liquid in the closure means is less than or equal to a first predetermined pressure. The spraying device also comprises a pressure reduction means mounted between said at least one nozzle and the second end, and a supply circuit as described above. In another aspect, the invention also relates to a liquid supply method for at least one spray boom, said spray boom comprising: - a pipe with a first end and a second end; at least one nozzle mounted between the first and the second end and comprising closure means for stopping the supply of said nozzle when the pressure of the liquid in the closure means is less than or equal to a first determined pressure; and a pressure reduction means mounted between said at least one nozzle and the second end. According to the method: in a first state, the first end is supplied with liquid at a pressure greater than the first determined pressure, in order to allow the liquid to be sprayed by said at least one nozzle; and in a second state, the second end is supplied with liquid at a pressure greater than the first predetermined pressure in order to stop the spraying of the liquid by said at least one nozzle.

According to another aspect, the invention also relates to a method of modifying a liquid supply circuit for at least one spray bar, said spray bar comprising a pipe with a first end and a second end, at least one nozzle mounted between the first and the second end and each comprising a closure means for stopping the supply of said nozzle when the pressure of the liquid in the closure means is less than or equal to a first determined pressure, and a means of pressure reduction mounted between said at least one nozzle and the second end, the supply circuit having a liquid supply at a pressure greater than the first determined pressure. According to the method, there is mounted between the liquid supply and the first and second ends a control means configured to connect, in a first state, the supply of liquid to the first end to allow the liquid to be sprayed by said liquid. less a nozzle, and configured to connect, in a second state, the liquid supply to the second end to stop the spraying of the liquid by said at least one nozzle.

Brief description of the drawings The invention and its advantages will be better understood on reading the detailed description of a particular embodiment, taken by way of non-limiting example and illustrated by the appended drawings in which: FIG. a schematic representation of a spraying device comprising a liquid supply circuit according to the invention, in a first state; - Figure 2 is a schematic representation of the spray device of Figure 1, in a second state; FIG. 3 is an external view of a four-way valve according to one aspect of the invention; and FIG. 4 is a cross-sectional view of the four-way valve of FIG. 3 associated with two other four-way valves. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 illustrates an exemplary embodiment of a device of FIG. spray 1 according to the present invention. The spraying device 1 comprises a feed circuit 2 and two spray nozzles 4 in the embodiment described, but may be in greater number. The spray bars 4 each comprise a pipe 6 with a first end 8 and a second end 10. Each pipe 6 also comprises spray nozzles 12 and a pressure reduction means 14 which are successively mounted between the first end 8 and the second end 10. A closure means 16 is associated with each spray nozzle 12, for example a calibrated valve-type anti-drop element. It is considered in the following description that the anti-drop element 16 is calibrated at 0.7 bar.

The spray nozzles 12 may comprise very different gauges ranging from 0.32 to 4 L / min with a feed pressure of 2 bars. The anti-drop element 16 may thus comprise a deformable membrane connected to elastic means, for example a spring, which tend to keep the membrane applied against a seat arranged in the pipe connecting the pipe 6 to the spray nozzle 12. When the pressure of the treatment liquid inside the pipe 6 is greater than the elastic force of the anti-drop elements 16 (0.7 bar), for example equal to 2 bar, the membranes thereof are removed from the seats under the effect of the liquid which can then flow from the pipe 6 to the nozzles 12 and be sprayed. Conversely, when the pressure of the treatment liquid is less than 0.7 bar, the membranes are held against their seat that they seal, and prevent the treatment liquid from circulating to the nozzles 12.

The reduction means 14 may be a pelletizing or any means for obtaining a pressure difference between the inlet and the outlet of the means 14. The reduction means 14 may thus be a pipe with a reduced diameter and / or or an elongate length to obtain the desired pressure drop between the spray nozzles 12 and the second end 10. The reduction means 14 allows in particular to implement a continuous circulation in the pipe 6. In fact, the liquid of treatment can be routed in line 6 continuously, without creating a liquid stagnation zone and without reducing the pressure in the pipe 6 at the spray nozzles 12, by evacuating the excess of treatment liquid by the means In addition, the use of a pressure reduction means 14, in combination with a return line, also makes it possible to increase the speed of circulation of the liquor. in the line 6 during spraying, in particular with nozzles 12 of small caliber.

Thus, the control of the pressure at the level of the anti-drop elements 16 makes it possible to control the spraying or not of the treatment liquid by the nozzles 12. The spraying device 1 thus comprises a feed circuit 2 making it possible to improve the stopping the spraying of the treatment liquid by the nozzles 12, after the actuation of a corresponding command. The supply circuit 2 conventionally comprises a reservoir 18 of treatment liquid. The treatment liquid, or "slurry", is generally a mixture of water and powder that can settle more or less rapidly in the bottom of the tank or pipe. The supply circuit 2 also comprises a distribution pipe 20 mounted at an outlet of the tank 18 and for conveying the treatment liquid from the tank 18 to the different spray bars 4. More particularly, the treatment liquid contained in the reservoir 18 is sucked into the distribution pipe 20 by a delivery pump 22, for example a piston or diaphragm type pump, which pumps it under pressure to the spray bars 4. The supply circuit 2 can also typically include a rinse tank (not shown) for containing clear water. The flushing tank can be mounted, for example via a three-way valve, on the distribution pipe 20, in parallel with the tank 18. The supply circuit 2 can also comprise, on the distribution pipe 20, downstream of the pump 22, a control means 24 of the treatment liquid flow, and one or more filters 26 able to retain certain particles contained in the treatment liquid. The supply circuit 2 finally comprises control means 28, each mounted between the distribution duct 20 and a spray bar 4. The control means 28 are in particular embodied in the example described by four-way valves. For connecting an outlet of the distribution line 20 to the first end 8 or to the second end 10 of the pipe 6 of a spray boom 4. Moreover, the control means 28 are also connected to the inlet 30 of a return pipe 32 comprising an outlet 34 opening for example into the tank 18. The return pipe 32 thus makes it possible to convey the surplus treatment liquid flowing in the pipe 6 of a spray boom 4, to the tank 18 or possibly to another tank. For this purpose, the return pipe 32 may also comprise a three-way valve 36, called a purge valve, mounted between the inlet 30 and the outlet 34 of the return pipe 32, and for connecting the inlet 30 of the return line 32 is at the outlet 34 or at a bypass line 38 for conveying the excess treatment liquid to a dedicated tank 40 or an evacuation pit, or even directly to the pump 22, for example in a suction manifold or in a suction pipe of the pump 22. The purge valve 36 and the dedicated reservoir 40 may be used in case of priming or cleaning the pipe 6 of the ramp 4 with clean water In order to prevent the diluted treatment liquid from being reintroduced into the supply tank 18 of the supply circuit 2. Alternatively, the rinsing liquid can be redirected directly to the pump 22 in order to be spread over surfaces during a summer pre-treatment ape or during a complementary processing step for example. When the spraying device 1 is put into service, it is considered that the spraying device 1 has been rinsed with clean water and that the lines 20, 6 and 32 contain water. In order to be able to spray the treatment liquid, it is thus necessary initially to replace the water present in the lines of the spraying device 1 with the treatment liquid to be sprayed: this is the step of priming the device. spray. For this purpose, the control means 28 are positioned so as to connect on the one hand the outputs of the distribution pipe 20 to the second ends 10, and on the other hand the first ends 8 to the inlets 30 of the return pipe 32 On the other hand, the purge valve 36 can be operated to direct the mixture of clean water and process liquid to a dedicated container 40 so as not to alter the dilution of the process liquid in the reservoir 18. The treatment liquid thus passes successively through the pump 22, the flow control means 24, the filters 26, the control means 28, the pressure reduction means 14, the anti-drop elements 16, the control means 28 the return line 32, the purge valve 36 and the bypass line 38 to enter the reservoir 40. The circulation of the process liquid in the pressure reduction means 14 before the anti-drip elements 16 makes it possible to reduce the pressure of the treatment liquid at the level of the anti-drop elements 16 to a value of less than 0.7 bar, which makes it possible to circulate the treatment liquid in the pipe 6 of the ramp 4 without spraying it with The nozzles 12 thus obtain a continuous circulation of the treatment liquid in the spraying device 1 without spraying, thus making it possible to limit the deposits of particles in the pipes or in the various elements mounted on the pipes, while allowing the device to spray 1 to be ready to spray. When the user wishes to start spraying the treatment liquid, for example with the two ramps shown in FIG. 1, the control means 28 are actuated so as to connect, on the one hand, the outputs of the distribution pipe 20 to the first ends 8, and secondly the second ends 10 at the inlets 30 of the return line 32. The treatment liquid circulating in the anti-drop elements 16 then has a pressure greater than the opening pressure of said anti-drop elements. drop 16. The treatment liquid is then sprayed by the nozzles 12 of the two ramps 4 on the surfaces to be treated (Figure 1). The excess of treatment liquid supplying the lines 6 is conveyed through the pressure reduction means 14 and then through the return line 32 to return to the reservoir 18. The circulation thus performs continuously and avoids areas of stagnation in the pipe 6 where could be deposited particles of the treatment liquid. FIG. 2 represents the case in which the user wishes to stop spraying by one of the two ramps 4. In this case, the control means 28 associated with said ramp 4 are controlled so as to connect on the one hand the output of the distribution pipe 20 at the second end 10 of the ramp 4 in question, and secondly the first end 8 at the inlet 30 of the return pipe 32. During the change of the control means 28, the pressure of the Treatment liquid at the anti-drop elements 16 drops immediately by direct communication via the return line 32 to the tank 18 which is at atmospheric pressure. The pressure of the treatment liquid at the level of the anti-drop elements 16 then becomes substantially equal to the sum of the pressure of the reservoir 18 and the pressure drop of the return pipe 32. Moreover, the treatment liquid feeding the anti-drop element 16 also has a reduced pressure following the circulation of the treatment liquid in the pressure reduction means 14 mounted upstream of the drip-free elements 16. Thus, without changing the operation of the pump 22, it is possible, by operating the control means 28, to instantly change the pressure of the treatment liquid at the anti-drop elements 16 of a ramp 4, without changing the pressure of the treatment liquid in the liquid supply circuit 2 or in the other ramps 4. Moreover, even in the ramp 4 having stopped the spraying, there is always a continuous circulation of the treatment liquid in the pipe 6 permitting t avoid deposits. In order to resume the spraying with the ramp 4 stopped, it is then sufficient to again operate the associated control means 28, to obtain a sufficient process liquid pressure 30 again at the anti-drop elements 16 to obtain the spraying. To clean the spray device at the end of the work, it is sufficient to close the outlet of the tank 18 and supply the pump 22 with the clear water contained in the flushing tank. Furthermore, the control means 28 are manipulated so as to connect on the one hand the outlet of the distribution pipe 20 to the second end 10, and on the other hand the first end 8 to the inlet 30 of the pipe 32. Finally, the purge valve 36 can be operated to route the cleaning liquid to the dedicated reservoir 40 or directly to the pump 22. In this case, the clear water of the rinsing tank is circulated. in the different ramps 4 of the spraying device 1 and can be either recovered in the reservoir 40 is spread on surfaces not yet treated or treated incompletely. In particular, the routing of the rinsing liquid to the pump 22 for spraying makes it possible to use the rinsed (and therefore diluted) treatment liquid for a pre-treatment of untreated surfaces or for a complementary treatment of surfaces requiring it. Thus, thanks to the supply circuit 2 according to the invention, it is possible to control the spraying or the spray stop by the nozzles, more quickly and more reliably, while allowing a continuous circulation of the treatment liquid in ramp 4 to avoid deposits. FIG. 3 represents an external view of a four-way valve that can be used as control means 28 according to the invention. The four-way valve 28 comprises a frame 42, for example of generally parallelepipedal shape, traversed by two parallel pipes forming a first collector 44 and a second collector 46. The collectors 44 and 46 completely pass through the frame 42 and thus make it possible to mount in series several four-way valves 28 as described. The collectors 44 and 46 may be substantially perpendicular to both sides of the frame they pass through.

The four-way valve 28 also comprises a first connector 48 and a second connector 50 made, for example, in the form of holes disposed on the same face of the frame 42, different from those traversed by the two collectors 44, 46. FIG. a sectional view of a four-way valve shown in Figure 3, and associated with two other four-way valves. As can be seen, the collectors 44 and 46 of the four-way valve 28 extend into the adjacent four-way valves. It is thus easy to mount in series several four-way valves 28, each controlling the spraying of the treatment liquid by a ramp of the spray device.

Between the two collectors 44 and 46 is provided a rotary means 52 comprising a wall 53 mounted in a substantially cylindrical or spherical housing, and two lines 54 and 56 respectively connecting the first collector 44 and the second collector 46 to the rotary means 52. elsewhere, the four-way valve also comprises two elbows 58, 60 respectively connecting the rotary means 52 to the first connection 48 and to the second connection 50. More particularly, the two ducts 54, 56 are arranged in the plane of the two collectors 44, 46, perpendicular to the collectors 44, 46. The two pipes 54, 56 are mounted between the two collectors, along the same axis, and each communicate by a first end with one of the two collectors 44, 46, and by a second end with the rotating means 52. Moreover, each of the two elbows comprises a first portion in the plane of the collectors 44, 46, parallel to the collectors, and a second portion perpendicular to the plane of the collectors 44, 46. Thus, by operating the rotary means 52, it is possible to put in communication either the first collector 44 and the first connector 48 on the one hand, and the second collector 46 and the second connector 50 on the other hand, the first manifold 44 and the second coupling 50 on the one hand, and the second manifold 46 and the first coupling 48 on the other hand. For this purpose, the rotary means 52 may be connected, for example by a shaft (not shown) to a motor (not shown) fixed to the frame 42 and making it possible to turn the rotary means 52.

Machining holes, necessary for the realization of the four-way valve 28, can be visible on external surfaces of the frame. The valve 28 may thus comprise a hole 62 in the axis of the pipes 54, 56, and a hole 64 for producing the elbows 58 and 60, in particular first portions of the elbows 58, 60. The hole 64 may in particular be plugged by the side surface of the adjacent four-way valve. Regarding the hole 62 used to form the lines 54 and 56, a plug 66 must be arranged to prevent leakage. Thus, the four-way valve as illustrated in FIGS. 3 and 4 makes it possible to easily mount in series, and with a small overall size, several identical valves, each being connected, by the first manifold 44, to the distribution pipe 20 of the liquid supply circuit 2, and by the second manifold 46 to an inlet 30 of the return line 32. Each valve 28 is then specifically connected, for example by the first connector 48, to the first end 8 of the pipe 6 of the corresponding ramp 4, and the second connector 50 at the second end 10 of the pipe 6 of the corresponding ramp 4. The spray can thus be controlled independently by several spray bars 4 as described above.

Claims (12)

REVENDICATIONS1. A liquid supply circuit (2) for at least one spray boom (4), said spray boom (4) comprising: - a pipe (6) with a first end (8) and a second end (10); - at least one nozzle (12) mounted between the first (8) and the second end (10) and comprising a closing means (16) for stopping the supply of said nozzle (12) when the liquid pressure in the nozzle is less than or equal to a first predetermined pressure; and - pressure reducing means (14) mounted between said at least one nozzle (12) and the second end (10); the supply circuit (2) comprising: - a supply of liquid at a pressure greater than the first determined pressure; and control means (28) configured to connect, in a first state, the supply of liquid to the first end (8) to allow spraying of the liquid by said at least one nozzle (12), and configured to connect, in a second state, the supply of liquid to the second end (10) to stop the spraying of the liquid by said at least one nozzle (12). 2. Feeding circuit (2) according to claim 1 wherein the closure means (16) is a calibrated valve, preferably by an elastic means, for example a spring. 3. Feed circuit (2) according to claim 1 or 2 wherein the pressure reducing means (14) is adapted to provide, from the liquid supply, a liquid at a pressure less than or equal to the first determined pressure. The power supply circuit (2) according to any one of claims 1 to 3 further comprising a return line (32) comprising an inlet (30) and an outlet (34), and wherein, in the first state, the control means (28) is configured to connect the second end (10) to the inlet (30) of the return line, and in the second state, the first end (8) to the inlet (30) of the driving back. 5. Power supply circuit (2) according to the preceding claim wherein the control means (28) comprises a four-way valve configured: - to connect, in the first state, the liquid supply and the first end (8) on the one hand, and the second end (10) and the inlet (30) of the return pipe on the other hand; and - to connect, in the second state, the liquid supply and the second end (10) on the one hand, and the first end (8) and the inlet (30) of the return pipe on the other hand . 6. Power supply circuit (2) according to the preceding claim wherein the four-way valve comprises: - a frame (42); a first collector (44) connected to the liquid supply and passing through the frame; a second collector (46) connected to the inlet (32) of the return duct (30) and passing through the frame, parallel to the first collector (44); a first connector (48) intended to be connected to the first end (8); a second connection (50) intended to be connected to the second end (10); and a selection means adapted to make each of the collectors (44, 46) communicate with one of the two connectors (48, 50). 30 7. Supply circuit (2) according to the preceding claim wherein the selection means comprises: - two pipes (54, 56) arranged in the plane of the two collectors (44, 46), perpendicular to the collectors, the two pipes (54, 56) being mounted between the two collectors, along the same axis, and each communicating at a first end with one of the two collectors, and at a second end with a rotating means (52); and two elbows (58, 60), each comprising a first portion in the plane of the collectors (44, 46), parallel to the collectors, and a second portion perpendicular to the plane of the collectors, the elbows (58, 60) each connecting the rotary means (52) with one of the two connections (48, 50). 8. Power supply circuit (2) according to one of the preceding claims wherein the liquid supply comprises a liquid reservoir (18), a pump (22) mounted at the outlet of the reservoir and configured to supply the liquid to a liquid. pressure higher than the first determined pressure, and possibly a means of regulating the feed rate (24) and / or a filter (26). 9. Supply circuit according to claims 4 and 8 wherein the outlet (34) of the return line (32) is mounted upstream of the liquid reservoir (18). 10.A spray device (1) comprising: - a spray boom (4), said spray boom comprising a pipe (6) with a first end (8) and a second end (10), at least one nozzle (12) ) mounted between the first and second ends and each comprising closure means (16) for stopping the supply of said nozzle when the pressure of the liquid in the closure means is less than or equal to a first predetermined pressure, and pressure reducing means (14) mounted between said at least one nozzle and the second end (10); and - a power supply circuit (2) according to any one of the preceding claims. 11.A liquid supply method for at least one spray boom (4), said spray boom comprising: - a pipe (6) with a first end (8) and a second end (10); at least one nozzle (12) mounted between the first and the second end and comprising closing means (16) for stopping the supply of said nozzle when the pressure of the liquid in the closure means is less than or equal to a first determined pressure; and - pressure reducing means (14) mounted between said at least one nozzle and the second end (10); in which: - in a first state, the first end (8) is supplied with liquid at a pressure greater than the first predetermined pressure in order to allow the spraying of the liquid by said at least one nozzle (12); and in a second state, the second end (10) is supplied with liquid at a pressure greater than the first predetermined pressure in order to stop the spraying of the liquid by said at least one nozzle. 12. A method of modifying a liquid supply circuit (2) for at least one spray bar (4), said spray bar comprising a pipe (6) with a first end (8) and a second end ( 10), at least one nozzle (12) mounted between the first and the second end and each comprising closure means (16) for stopping the supply of said nozzle (12) when the pressure of the liquid in the means of closure (16) is less than or equal to a first predetermined pressure, and pressure reducing means (14) mounted between said at least one nozzle (12) and the second end (10), the supply circuit (2) comprising a supply of liquid at a pressure higher than the first predetermined pressure, in which a control means (28) configured to connect, in a first direction, is mounted between the liquid supply and the first and second ends (8, 10). state, has liquid feeding at the first end (8) to allow the spraying of the liquid by said at least one nozzle, and configured to connect, in a second state, the liquid supply to the second end (10) to stop the spraying the liquid through said at least one nozzle.