Spraying unit with purge function

Abstract

The present invention relates to a selective liquid spraying unit (1) comprising a liquid inlet (E0), a spray nozzle (8), a delivery channel (12) extending from the liquid inlet to the nozzle, optionally passing through a closable passage (2), and optionally a pneumatically actuated valve (3) with a pneumatic chamber (31) delimited by a diaphragm (32) and supplied by a second pneumatic inlet (E2), a first pneumatic inlet (E1) connected to the delivery channel via a check valve (14), the diaphragm being movable between a first position causing the closable passage to be closed and a second position causing the closable passage to be opened, so that sending air through the first pneumatic inlet allows the delivery channel and the nozzle to be purged, and a spraying system comprising one or more spraying units. Abstract figure: Figure 3

Description

Title of the invention: Spraying unit with purging function technical field

[0001] The present invention relates to the field of product spraying systems used in agricultural operations, particularly vineyards or orchards, but also in large-scale crop farms. These spraying systems are used to apply products, such as plant protection products or liquid fertilizers, to target vegetation.

[0002] The target vegetation may be, on the one hand, cereal, protein crop or oil crop, or on the other hand, tree foliage, shrub foliage, vine foliage, etc... STATE OF THE ART

[0003] Spraying systems allow treatment liquid to be dispensed in the form of droplets onto the vegetation to be treated.

[0004] A farmer typically carries out spraying campaigns on one or more plots of crops, orchards, or vineyards. Between two spraying campaigns, it is common practice to rinse the equipment used, namely the product tank, the pump, the nozzles, and the various pipes involved. Rinsing is necessary between two successive campaigns of a given product, and even more so when two successive campaigns use two different treatment products that must not be contaminated by any residue of the previous product.

[0005] However, a spraying campaign can last several hours with breaks, or even extend over several days. Furthermore, there are cases where rinsing is not performed between two campaigns carried out in quick succession. In such cases, liquid product remains in the various pipes leading from the pump to the nozzles (indeed, in every circuit there is a "dead" volume that must be rinsed).

[0006] In this field, there are spraying systems equipped with so-called 'drip-stop' devices with a pneumatically or electrically controlled valve that isolates the spray nozzle from the upstream treatment product circuit. In a typical configuration, a pneumatically or electrically controlled valve is provided near each nozzle.

[0007] When the pneumatically or electrically operated valve is closed, the portion of piping located between the pneumatically (or electrically operated) valve and the nozzle is indeed isolated from the upstream distribution circuit, but there remains liquid in this portion of piping.

[0008] It is often observed that the nozzle orifice retains a drop, particularly by capillary action due to the small diameter of the orifice (or orifices).

[0009] The presence of this drop (these drops) eventually leads to a deposit of material at each nozzle orifice.

[0010] This is all the more pronounced when the treatment liquid is thick and / or viscous. The nozzle orifice may be more or less blocked. The internal surface of the nozzle may also be coated with a deposit that accumulates over time.

[0011] This deposit eventually alters the characteristics of the orifice and ultimately degrades the quality of the spraying.

[0012] This phenomenon necessitates periodic cleaning of the nozzle orifices. Such periodic cleaning is tedious. Moreover, such cleaning can generate a risk of damage to the nozzle orifice.

[0013] Therefore, there is a need to prevent such a droplet from forming at the nozzle orifice when the spray is inactive for that nozzle. All or some of the nozzles can be deactivated depending on the current spraying scenario and / or the operating conditions of the system. PRESENTATION OF THE INVENTION

[0014] In this context, the present invention relates, according to a first aspect, to a selective liquid spraying unit comprising a liquid inlet, a spray nozzle, a delivery channel extending from the liquid inlet to the spray nozzle, characterized in that the spraying unit comprises a first pneumatic inlet connected to the delivery channel via a non-return valve, so that sending air through the first pneumatic inlet, when the liquid inlet is no longer delivering liquid, allows the delivery channel and the nozzle to be purged.

[0015] Thanks to these features, it is possible to purge the internal volume of the nozzle (dead volume) and blow away any droplet that may have formed at the nozzle orifice. Furthermore, purging the delivery channel prevents another droplet from reforming due to vibration. This prevents the spray product from crystallizing in place and substantially reduces the need for nozzle cleaning.

[0016] As will be seen in more detail later, several ways are planned to generate an airflow in the first pneumatic inlet.

[0017] It should be noted that the non-return valve allows air to pass from the first pneumatic inlet to the delivery channel but prevents liquid, under pressure or not, located in the delivery channel from flowing back to the first pneumatic inlet.

[0018] It is noted that the valve which selectively authorizes or interrupts the delivery of liquid product can be arranged in the spraying unit or can be arranged remotely from the spraying unit, for example in a section head which serves several spraying units.

[0019] According to one embodiment, the delivery channel extends from the liquid inlet to the spray nozzle via a closable passage, and the spray unit comprises a pneumatically actuated valve with a pneumatic chamber delimited by a diaphragm and supplied with air by a second pneumatic inlet. The diaphragm is movable between a first position causing the closable passage to be closed and a second position causing the closable passage to be opened, so that sending air through the first pneumatic inlet when the closable passage is closed allows the delivery channel and the nozzle to be purged. The diaphragm is preferably flexible.

[0020] Such a pneumatically controlled valve proves to be reliable and inexpensive. It withstands the physicochemical and environmental stresses generally encountered by product spraying systems used in agricultural and viticultural operations. It should be noted that there is no electricity in the spraying unit.

[0021] It is noted that the pneumatically actuated valve and the diaphragm can form a normally closed or normally open configuration. In the normally closed configuration, energy must be supplied to leave the normally closed state. In the normally open configuration, energy must be supplied to leave the normally open state.

[0022] Furthermore, it is noted that the closable passage is located in the immediate vicinity of the nozzle, and consequently, the dead volume between the closable passage and the nozzle orifice is relatively small. The volume to be purged is therefore small, the product wasted is minimal, and it is not necessary to blow a large volume of air to purge the dead volume of interest and remove the potential drip at the nozzle orifice.

[0023] The term 'lung' is sometimes used in the jargon to refer to the pneumatic chamber of the pneumatically operated valve.

[0024] According to one embodiment, the pneumatically controlled valve is of the normally closed type.

[0025] Energy, in this case pneumatic, must be supplied to open the passage and allow the product to be delivered by the corresponding nozzle. This ensures the safe delivery of the treatment product.

[0026] According to one embodiment, the pneumatically controlled valve is of the normally open type.

[0027] This is the reverse logic of the previous one; when the upstream liquid circuit is under pressure, by default spraying occurs, a control must be applied to prevent spraying. This is an inhibition logic.

[0028] According to an alternative embodiment to the pneumatically operated valve, the spraying unit may include an electrically operated valve comprising a piston, the piston being movable between a first position causing the closable passage to be closed and a second position causing the closable passage to be opened. This provides the flexibility afforded by electrical control.

[0029] According to one embodiment, the spraying unit further comprises a unit body forming a structure on which the nozzle and the pneumatically controlled valve are fixed.

[0030] Wherefore, said unit body ensures the cohesion of the unit and the mechanical protection of the components which are housed in the unit body.

[0031] According to one embodiment, the delivery channel is arranged and formed in the unit body.

[0032] Wherefore, the delivery channel is integrated directly into the unit body, which increases the integration of the spraying unit and reduces its cost price because no pipe is then required for the delivery channel.

[0033] The present invention also relates, according to a second aspect, to a spraying system comprising a plurality of spraying units as described above and at least one pneumatic solenoid valve selectively supplying compressed air to the first pneumatic inlets (El) of the spraying units.

[0034] The pneumatic solenoid valve in question allows for the activation of a blow-off at the opportune moment after the liquid spray from the nozzle has stopped. It is a selective control of the airflow entering through the first pneumatic inlet. This selective control has a short duration, for example, from 0.5 seconds to 2 seconds.

[0035] According to one embodiment, the pneumatic solenoid valve is a 3 / 2 pneumatic solenoid valve with the purge port connected to the first pneumatic inlets of the spraying units.

[0036] In this case, we take advantage of the pneumatic solenoid valve which controls the pneumatically controlled valve and we take advantage of a volume of compressed air which is to be evacuated at the time of the interruption of spraying, a volume of air which is redirected (or diverted) to the first pneumatic inlet of the spraying unit.

[0037] In this case, the pneumatically operated valve is of the normally closed type. This will be explained in detail later with reference to [Fig. 4].

[0038] According to one embodiment, the pneumatic solenoid valve is a specific pneumatic solenoid valve. This forms a flexible control that can respond to several predefined logics; for example, the blowing time can be parameterized.

[0039] In practice, this is a specific pneumatic solenoid valve for purging, separate from the one that controls the diaphragm. This will be explained in detail later with reference to Figures 5 and 6.

[0040] According to one embodiment, the spraying system may comprise several spraying units functionally arranged in parallel by groups or subsets. These groups or subsets may be controlled independently of each other.

[0041] According to one embodiment, the spraying system may include at least one valve for delivering the treatment product. This valve may be controlled by a control unit which is also responsible for operating the aforementioned pneumatic or electric valves, so as to control the delivery of the treatment product and the associated pneumatic lines in a synchronized and consistent manner.

[0042] According to a first possibility, the liquid product delivery valve may be a main valve located remotely from the spraying unit, without a local shut-off valve inside the spraying unit. In a second possibility, the liquid product delivery valve is located inside the spraying unit and may (or may not) be supplemented upstream by a collective control valve for a section of the system.

[0043] According to one embodiment, a valve is provided for delivering the treatment product to each group or sub-assembly. For each group or sub-assembly, the control unit manages both the delivery of the liquid and the activation of the pneumatic controls. PRESENTATION OF THE FIGURES

[0044] The invention will be better understood upon reading the following description, given solely by way of example, and referring to the accompanying drawings given by way of non-limiting examples, in which identical references are given to similar objects and on which:

[0045] Fig. 1 is a schematic representation for elevation of an example of a spraying system in action in an orchard, with six spraying columns, and 24 spraying nozzles;

[0046] Figure 2 shows an example of a hydraulic diagram of the spraying system according to a generic embodiment of the present invention;

[0047] Fig. 3 schematically shows an example of the realization of a spraying unit with a locally pneumatically controlled normally closed valve;

[0048] Fig.4 illustrates the pneumatic circuit diagram associated with the example of a spraying unit embodiment shown in Fig.3;

[0049] Fig. 5 schematically shows an example of the realization of a spraying unit with a locally pneumatically controlled normally open valve;

[0050] Fig. 6 illustrates the pneumatic circuit diagram associated with the example of a spraying unit shown in Fig. 5;

[0051] [Fig.7] shows a timing diagram which illustrates an example of interruption of spraying and purging in the system shown in [Fig.4];

[0052] [Fig.8] shows a timing diagram which illustrates an example of interruption of spraying and purging in the system shown in [Fig.6];

[0053] Fig. 9 schematically shows another example of the realization of a spraying unit, in a simplified version, with the liquid delivery control valve located remotely.

[0054] It should be noted that the figures describe the invention in detail to enable its implementation; although not limiting, these figures serve in particular to better define the invention where appropriate. For the sake of clarity, some elements are not necessarily shown to scale. DETAILED DESCRIPTION OF THE INVENTION

[0055] The invention relates to a system for spraying a product in liquid form, the product being intended to be projected in the form of droplets onto a target vegetation denoted TV. The product to be sprayed may be a plant protection product or a liquid fertilizer.

[0056] In large-scale crop farming, the target vegetation will typically be cereals, protein crops, legumes, oilseeds, etc. In vineyards or orchards, the target vegetation will typically be tree or shrub foliage, or vineyard foliage. It should be noted that the target vegetation can be any type of vegetation within the meaning of the present invention.

[0057] The spraying system can be attached to a straddle tractor-type agricultural implement as shown in [Fig. 1], or to a conventional tractor. In another application, the spraying system is attached to an agricultural implement towed by a tractor.

[0058] By convention, the direction of advance of the agricultural machine is designated by the frame X forming the so-called longitudinal axis, the direction transverse to the longitudinal displacement by the frame Y and the vertical direction by the frame Z.

[0059] According to the example illustrated in [Fig. 1], the spraying system may comprise a plurality of treatment sets, generally arranged in pairs, each pair being intended to treat one row of vegetation. For example, the system may comprise two treatment sets to treat one row of vegetation, or four treatment sets to treat two rows of vegetation, or six treatment sets to treat three rows of vegetation as illustrated, and so on.

[0060] According to the example illustrated in [Fig. 1], the spraying system comprises six spraying columns, respectively labeled Cl, C2, C3, C4, C5 and C6. The spraying columns are supported by a structural cross member labeled 24. Each spraying column comprises four nozzles in the illustrated example.

[0061] Each of the columns can form a pneumatic section controlled selectively via the respective pneumatic lines Fl, F2, F3, F4, F5 and F6.

[0062] According to the example illustrated in [Fig. 1], in the operating configuration, the treatment units extend substantially vertically to a height ideally corresponding to the height of the vegetation to be treated. The direction of product spraying extends substantially horizontally.

[0063] In treatment configuration, as seen in [Fig.1], two spray columns frame a row of vegetation TV or in other words a row of vegetation is interposed between two spray columns located opposite each other, and which spray the treatment product towards the vegetation.

[0064] According to various embodiments, the configuration and geometric arrangement of the nozzles may differ. The nozzles may be grouped into sets or subsets according to the application logic of the treatment product and the vegetation to be treated. In other words, several sections or parts are provided that can be activated or deactivated independently of each other.

[0065] For example, in a large-scale farming context, not shown in the figures but very common, horizontal booms (i.e., long horizontal arms) are used in the operating configuration with nozzles that project the treatment product downwards. The booms may be telescopic and can extend over a considerable length in the operating configuration. Under certain operating conditions, it may be necessary to disable some of the nozzles to prevent misuse.

[0066] Each spray column C1-C6 comprises a plurality of spray nozzles 8. The spray nozzles 8 are arranged one after the other in a vertical direction in a spraying configuration, with a The spacing between nozzles is approximately twenty or thirty centimeters, for example. Depending on the type of vegetation to be treated, the number of nozzles per column can range from three to ten, for example.

[0067] Each spray nozzle 8 is included in an entity called a spray unit and identified as 1.

[0068] In a generic way, the spraying system includes a pumping unit noted 9 for pumping the treatment product from a product tank 90 forming a reservoir for the treatment liquid 18.

[0069] The pumping unit 9 comprises a pump 91 and a motor 92 configured to drive the pump in rotation. The motor 92 can be an electric motor or a hydraulic motor.

[0070] Liquid pipes collectively identified by reference 94 are provided to convey the pressurized liquid to the spray nozzles.

[0071] The proposed spraying system includes an electropneumatic unit 7. The electropneumatic unit 7 includes a compressor 71 driven by a motor 72 configured to drive the compressor. The motor 72 can be an electric motor or a hydraulic motor (in which case the electropneumatic unit is a hydropneumatic unit).

[0072] The electro-pneumatic unit 7 may further include one or more solenoid valves, which will be discussed later. The solenoid valves may be integrated into the electro-pneumatic unit or may be located remotely from the electro-pneumatic unit.

[0073] Pneumatic lines collectively identified by reference 74 are provided to convey compressed air to the spraying units 1, via where appropriate one or more pneumatic or electropneumatic valves which will be discussed later.

[0074] Fig. 2 schematically illustrates the hydraulic and pneumatic system used in the spraying system.

[0075] The spraying system includes a control unit, designated 15, which in the illustrated example controls the pneumatic compressor motor and the liquid pump motor. A control panel 25, or equivalent, is provided, allowing an operator to start or stop a spraying sequence. If necessary, the control panel 25 allows the operator to define groups or subsets of nozzles to be temporarily or intermittently deactivated, and to control the corresponding pneumatic solenoid valves accordingly.

[0076] Furthermore, for the operation of the control unit, various sensors 16 and / or pushbuttons 17 are provided, for example pressure sensors, temperature sensors, level sensors, activation buttons, on / off buttons, as known per se, therefore not described in detail here.

[0077] Figure 2 shows a single spray column Cl which is supplied on the one hand by means of a liquid pipe 94, and on the other hand by means of one or two pneumatic lines 74, according to several possible embodiments which will be seen below.

[0078] A pneumatic solenoid valve 4 is provided to supply compressed air to the spray column. It should be noted that one or more other pneumatic solenoid valves 4' can be provided in parallel to supply other spray columns.

[0079] A valve 6 is provided to supply the treatment liquid to the spray column. It should be noted that one or more other valves 6' can be provided in parallel to supply treatment liquid to other spray columns.

[0080] With reference to [Fig.3], the spraying unit 1 includes a spray nozzle 8 and a pneumatically controlled valve 3 which allows the pressurized treatment liquid to be selectively sent to the nozzle or not.

[0081] In addition, the spraying unit 1 includes a liquid inlet marked E0, and a delivery channel 12 extending from the liquid inlet to the nozzle via a closable passage 2.

[0082] In this first embodiment, the pneumatically controlled valve 3 is of the normally closed type.

[0083] The spraying unit 1 includes a first pneumatic inlet El which will be discussed later.

[0084] The pneumatically actuated valve 3 comprises a pneumatic chamber 31 ('lung') delimited by a diaphragm 32 and a valve body 30. The valve body may, for example, generally be cylindrical. The diaphragm 32 is in the form of a flexible disc, anchored at its peripheral edge to the valve body.

[0085] The pneumatic chamber 31 is in fluid communication with a second pneumatic inlet E2 from the compressed air line 49 which leads to the spraying unit.

[0086] In other words, the pneumatically controlled valve is supplied by the second pneumatic inlet E2.

[0087] In the illustrated example, a piston 20 is provided with one or two peripheral O-rings 27. The piston 20 separates the pneumatic section (above) from the hydraulic section (below). The central area of ​​the flexible diaphragm is connected to the piston 20. Thus, the piston 20 is driven in its vertical sliding motion by the flexible diaphragm 32.

[0088] At the base of the valve, there is a closable passage 2, with a valve 21 and a valve seat 23. More specifically, a control rod 22 is fixed on one side to the piston 20 and on the other hand to the center of the valve 21, the rod 22 passes through the valve seat 23 which is annular in shape.

[0089] The flexible membrane 3 is forced upwards against the pneumatic pressure by means of a helical spring 33. The flexible membrane 3 drives with its movement the piston 20 and the valve 21.

[0090] Thus, when the pneumatic chamber is not pressurized, that is to say not supplied with compressed air, the flexible diaphragm 32 and the piston are pulled upwards by the return spring 33 and the valve 21 comes to rest against the valve seat 23 thus closing the closable passage.

[0091] Conversely, when the pneumatic chamber is supplied with compressed air, the flexible diaphragm 32 is displaced downwards by the pneumatic pressure against the spring (which is then compressed), the piston 20 is displaced downwards, and the passage between the valve 21 and the valve seat 23 is opened. A liquid flow, denoted FL, is then established from the liquid inlet E0 to the delivery channel 12 and then to the spray nozzle 8. The liquid then passes from the annular chamber 28 located around the rod 22 through the open valve seat and towards the nozzle 8.

[0092] Expressed in other words, the central area of ​​the flexible membrane is movable between a first position causing the obturable passage 2 to be closed (state represented in dotted lines in [Fig.3]) and a second position causing the release of said obturable passage (state represented in solid line).

[0093] Alternatively, the return spring 33 could be placed under the piston, in the liquid compartment and could then push the piston upwards.

[0094] In addition, the first pneumatic inlet El of the spraying unit, already mentioned, is connected to the delivery channel 12. A branch is provided in the spraying unit for the supply of blowing air.

[0095] Advantageously, the first pneumatic inlet El is connected to the delivery channel via a non-return valve 14.

[0096] The non-return valve 14 allows air to pass from the first pneumatic inlet El to the delivery channel but prevents liquid in the delivery channel 12 from flowing back to the first pneumatic inlet El.

[0097] According to one embodiment, the check valve 14 comprises a movable valve element between a closed position in which this element is pressed against a valve seat and an open position in which the valve element is moved away from the valve seat. It is also possible to use a check valve in the form of a ball received in a conical seat and returned by a small return spring.

[0098] The check valve 14 can be calibrated to open under a pressure difference between 500 millibar and 2 bar on the side of the first pneumatic inlet El.

[0099] It is noted that the airflow through the non-return valve, denoted RI, is unidirectional, whereas the airflow R2 at the second inlet E2 is bidirectional. The airflow R2 enters to inflate the pneumatic chamber and is expelled (exited) in the opposite direction when the chamber's pressure drops.

[0100] In addition, the spraying unit 1 includes a unit body 10 forming a structure on which the nozzle 8 is fixed. The pneumatically controlled valve 3 is also fixed to the unit body 10. The unit body 10 may include fixing lugs or other accessory elements.

[0101] A flange 11 is provided which clamps a collar 81 belonging to the nozzle to hold the nozzle on the unit body 10. The nozzle is thus replaceable if necessary.

[0102] In the illustrated example, the delivery channel 12 is formed directly in the unit body 10.

[0103] Figure 4 shows the liquid and pneumatic circuits that supply two spraying units.

[0104] The pneumatic solenoid valve 4 receives an electrical command from the control unit 15 via the control line 13.

[0105] The pneumatic solenoid valve includes a movable spool, otherwise called a core, which is moved inside a cylindrical solenoid valve body, as known per se, under the effect of a force generated by an electromagnetic force induced by the current passing through the coil and under the effect of an opposing force provided by a return spring 40.

[0106] Ports are provided on the cylindrical body which receives the drawer.

[0107] A first port 41 receives compressed air from the pneumatic compressor 71 via the line 74. A second port 42 forms the outlet to the spraying units, more specifically the pneumatic chambers 31 via the line 49. A third port 43, which normally corresponds to the vent to the open air, is here cleverly connected to the first pneumatic inlets El of the spraying units, via a diverter line marked 48.

[0108] The pneumatic solenoid valve 4 is of type 3 / 2 (two positions, three ports).

[0109] The part marked 4A of [Fig.4] represents the solenoid valve in its state activated by the coil, while the part marked 4B represents the solenoid valve in an inactive state, i.e. at rest under the effect of the return spring.

[0110] In the activated state, the orifice 47 of the core makes the first port 41 communicate with the second port 42 and supplies compressed air to the pneumatic chamber 31 via the conduit 49 and the second air inlet E2.

[0111] In the inactivated resting state, the orifice 46 of the core connects the second port 42 with the third port 43 and the identified diversion conduit 48.

[0112] The volume of air that was stored in the pneumatic chamber 31 is therefore not evacuated to the open air but redirected to the first inlet El of the spraying unit in order to push the liquid that is in the delivery channel 12 outwards via the nozzle orifice.

[0113] The volume of air stored in the pneumatic chamber 31 represents a sufficient air reserve to purge the delivery channel 12.

[0114] In other words, thanks to the diversion line 48, an air supply via the first pneumatic inlet El, when the closable passage is closed, allows the delivery channel 12 and the nozzle 8 to be purged.

[0115] It is noted that when the pneumatic solenoid valve 4 is activated, the third port 43 is located opposite a closed wall (represented by a dead end 44) ​​thus isolating the bypass pipe 48 which remains protected from any external pollution.

[0116] Figure 7 illustrates a timing diagram of the spray interruption sequence on a spraying unit. Pressure PR1 is the pressure at the first pneumatic inlet E1. Pressure PR2 is the pressure at the second pneumatic inlet E2 and in the pneumatic chamber 31.

[0117] At time t1, the electrical control 45 of the solenoid valve 4 switches from On to Off. The spool is then returned to its rest position by the spring 40. The air supply from the compressor is stopped. The air contained in the lung flows through the bypass line 48 towards the first pneumatic inlets E1 of the spray units. PR2 = PR1.

[0118] At time t2, the majority of the liquid that was contained in the delivery channel 12 has been expelled by the nozzle and the air can directly exit through the nozzle orifice, which causes the air pressure to drop rapidly and then tend towards 0.

[0119] With reference to a second embodiment shown in [Fig.5], the spray unit 1 includes a spray nozzle 8 and a pneumatically controlled valve 3 which is of the normally open type, contrary to the configuration shown in [Fig.3].

[0120] The elements which are not described again here are identical or similar to those which have been described with reference to [Fig.3].

[0121] As before, the pneumatic solenoid valve 4 controls the pneumatically operated valve 3, according to the logic already described, with the opposite effect on the closable passage. When the pneumatic solenoid valve 4 is energized, the passage 2 is closed, whereas when the pneumatic solenoid valve 4 is at rest, the passage 2 is open.

[0122] However, this pneumatic solenoid valve 4 is not used for blowing air for the purpose of purging the nozzle; another solenoid valve, specific to purging the nozzle, and designated 5, is provided for this purpose.

[0123] When the pneumatic chamber is not pressurized, i.e., not supplied with compressed air, the flexible diaphragm 32 is returned upwards by the return spring 33. The piston is also thereby returned upwards. The closable passage 2 is then opened. A liquid flow, denoted FL, is then established from the liquid inlet E0 to the delivery channel 12. The liquid flow FL passes from the outside to the inside of the conduit 26.

[0124] Conversely, when the pneumatic chamber is supplied with compressed air, the flexible diaphragm 32 is displaced downwards by the pneumatic pressure against the spring (which is then compressed). In this position, the central area of ​​the diaphragm pushes the piston 20, which presses against an annular seat 29, and consequently closes the closable passage 2. The flow of liquid FL is then interrupted.

[0125] It is therefore the piston 20 which acts as a valve, under the effect of the movements imparted to the flexible diaphragm 3 by the pressure prevailing in the pneumatic chamber 31.

[0126] Fig. 6 shows the function of the specific solenoid valve 5 acting on the purge.

[0127] The part marked 6A of [Fig.6] represents the specific solenoid valve 5 in an inactive state, i.e. at rest under the effect of the return spring, while the part marked 6B represents the specific solenoid valve 5 in its state activated by the coil.

[0128] Ports are provided on the cylindrical body that receives the drawer. A first port 51 receives compressed air from the compressed air line 75. A second port 52 forms the outlet to the first pneumatic inlets El of the spraying units, via the air line 58.

[0129] Normally, the specific solenoid valve 5 is not powered and its second port 52 is connected to a closed wall 59, so as to preserve the integrity and cleanliness of the supply lines 58 of the first pneumatic inlets El.

[0130] The specific solenoid valve 5 is only controlled when there is a need to purge the delivery channel and the drip from the nozzle orifice.

[0131] When the specific solenoid valve 5 is excited or activated (sketch 6B), the first port 51 is connected by fluid communication with the second port 52 and compressed air is directed from the compressed air line 75 to the supply lines of the first pneumatic inlets El via the air line 58 to purge the delivery channel and the nozzle.

[0132] In [Fig.8], the signal 55 corresponds to the excitation of the specific solenoid valve 5.

[0133] The instant te corresponds to the moment of the interruption of the command on the pneumatic solenoid valve 4 controlling the lung 31 of the pneumatic valve 3. The pressure PR2 in the chamber 31 decreases from this moment.

[0134] The instant td corresponds to the beginning of the blowing sequence, the moment when the specific solenoid valve 5 is controlled by the signal 55 and goes to the activated state (from OFF to ON).

[0135] The pressure PR1 increases abruptly until the instant tf when the specific solenoid valve 5 is deactivated and returns to its rest state (from ON to OFF). The blowing time denoted TS, see [Fig. 8], can advantageously be set in the control unit 15.

[0136] Figure 9 shows another example of an embodiment of a spraying unit 1, without a local valve for liquid distribution. The valve that allows the passage of fluid or interrupts the delivery of fluid, denoted 60, is located remotely, for example in the common manifold of a distribution section.

[0137] For the rest, the spraying unit 1 is identical or similar, mutatis mutandis, to what has been described previously in relation to figures 5 and 6. but without the presence of a local control valve, the inlet E0 is in permanent communication with the delivery channel 12.

[0138] Considering the normally open type solution shown in [Fig.5] and 6, the invention also covers, mutatis mutandis, the case of an electrically operated valve instead of a pneumatically operated valve.

[0139] In general, the pneumatically operated valve 3 could be different from that shown in Figures 3 and 5: other types of pneumatically operated valve may be used, in particular with rigid pistons and connecting rods.

[0140] Similarly, the liquid chamber inside the spraying unit could be different from that shown.

[0141] It should also be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to a person skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0142] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiment set forth in this description, but shall be interpreted to include all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Demands

1. Selective liquid spraying unit (1) comprising a liquid inlet (EO), a spray nozzle (8), a delivery channel (12) extending from the liquid inlet to the spray nozzle, characterized in that the spraying unit comprises a first pneumatic inlet (El) connected to the delivery channel via a check valve (14), such that sending air through the first pneumatic inlet, when the liquid inlet is no longer delivering liquid, allows the delivery channel and the nozzle to be purged.

2. Spraying unit (1) according to claim 1, wherein the delivery channel (12) extends from the liquid inlet to the spray nozzle via a closable passage (2), a pneumatically controlled valve (3) with a pneumatic chamber (31) delimited by a membrane (32) and supplied by a second pneumatic inlet (E2), the membrane being movable between a first position causing the closable passage to be closed and a second position causing the closable passage to be opened, so that sending air through the first pneumatic inlet when the closable passage is closed allows the delivery channel and the nozzle to be purged.

3. Spraying unit (1) according to claim 2, wherein the pneumatically operated valve is of the normally closed type.

4. Spraying unit (1) according to claim 2, wherein the pneumatically operated valve is of the normally open type.

5. Spray unit (1) according to any one of claims 1 to 4, further comprising a unit body (10) forming a structure on which the nozzle and pneumatically controlled valve are fixed.

6. Spraying unit (1) according to any one of claims 1 to 5, wherein the delivery channel (12) is arranged and formed in the unit body.

7. Spraying system (100) comprising a plurality of spraying units according to any one of claims 1 to 6, and at least one pneumatic solenoid valve (4,5) selectively supplying compressed air to the first pneumatic inlets (El) of the spraying units (1).

8. Spraying system according to claim 7, wherein the pneumatic solenoid valve (4) is a 3 / 2 pneumatic solenoid valve with the purge port connected to the first pneumatic inlets (El) of the spraying units (1).

9. Spraying system according to claim 7, wherein the pneumatic solenoid valve is a specific pneumatic solenoid valve (5).

10. Spraying system according to any one of claims 7 to 9, comprising several spraying units (1) functionally arranged in parallel by groups or subsets.

11. Spraying system according to any one of claims 7 to 10, comprising at least one delivery valve (6,60) for the treatment product.

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