FR2616084A1 - Device for supplying a spray boom with liquid - Google Patents

Abstract

The invention relates to a system for supplying liquid to a spray boom, in particular an agricultural spray boom. The boom includes at least one section 4, 5 carrying nozzles 8. A closure device 7 is associated with each nozzle and it is of the type including an inlet 14, a control inlet 15 for closure by the liquid to be sprayed, a supply outlet of the associated nozzle 8 and closure means. A valve 18 is mounted on the feed pipe 13 downstream of the closure device associated with the final nozzle of the section, in order to occupy an at least partially closed position and an open position. A return pipe 19 goes from the valve 18 to the tank 10, successively operating the closure devices associated with the nozzles by means of their control inlet 15. Depending on the position of each valve 18, the closure devices 7 are open or closed and the liquid is sprayed by the nozzles 8 or returns to the tank, via a continuous circulation, through the return pipe 19.

Description

 The invention relates to a liquid supply system for a sprayer boom. It applies in particular, without limitation, to supply systems for an agricultural sprayer boom.

 Among these supply systems, the invention relates to those of the type in which each spray nozzle is associated with its own shutter which is located in its immediate vicinity. In such an arrangement, it is obtained that, when the shutter is controlled in the closing direction, the stopping of the supply of the liquid to the nozzle is instantaneous, which avoids the very annoying phenomenon of drip, especially in agriculture.

 The invention also applies, at the same time, to supply systems in which, even when the nozzles are closed, there is a permanent circulation, known as continuous circulation, in the liquid conveying lines, which makes it possible to keep the liquid in motion and thus avoid the deposit of treatment particles which must be projected by the nozzles at the same time as the liquid to be sprayed.

 The object of the invention is to provide a supply system of the type indicated above which is of a simple and inexpensive structure, while being reliable.

 To this end, the supply system according to the invention for supplying at least one section, or ramp element, carrying nozzles, each nozzle being associated with a shutter of the type comprising a first inlet for supplying liquid to be sprayed, a second input for controlling the liquid to be sprayed itself, a supply outlet for the associated nozzle and sealing means for placing the first supply inlet selectively in communication or out of communication with the outlet, is characterized by the fact that it comprises: a feeder pipe supplied with liquid to be sprayed from a reservoir and a pump and in turn supplying successively the nozzles of said section by the first inlet of the associated shutters, a valve mounted on the feed line downstream of the shutter associated with the last nozzle of the section and suitable for occupying an at least partially closed position and an open position, and a return line leading from the valve to the reservoir and successively controlling, via their second control input, the shutters associated with said nozzles, the assembly being such that, depending on the position of the valve, the liquid to be sprayed, from the feeder line, is either directed at least partially towards the nozzles through the at least partially open shutters, or directed completely back towards the reservoir, through the return pipe which keeps the shutters in the closed position.

 With such an arrangement, on the one hand, the shutters are controlled directly by the spraying liquid, on the other hand, drips are avoided thanks to the proximity of the pairs of shutters and nozzles, and on the other hand on the other hand, a continuous circulation of the liquid is maintained, from the reservoir and the feeder line, by projection through the nozzles and / or by return to the tank through the return line.

 Preferably, the valve has a position which is only partially closed in order to permanently maintain a circulation of the spraying liquid in the return line and thus ensure a continuous circulation.

 A flow limiter is mounted on the return line, downstream of the shutter associated with the last nozzle of the section, to maintain in the return line an active pressure for closing the shutters when the valve is open.

 Each shutter is of the differential type and comprises a piston movable on the opposite faces from which the pressure of the spraying liquid present in the feed line and in the return line acts. Preferably, the area of the face of the piston on which the liquid in the feed line acts is less than the area of the face of the piston on which the liquid in the return line acts, so as to ensure good closure of the shutters when the valve is open.

 Preferably, a membrane is interposed between each face of the piston and the liquid.

 In the case where there are several sections or ramp elements, a valve and a return line to the tank are associated with each section, each return line either leading directly to the tank, or being equipped with non-return means, downstream of which it opens into a common collecting pipe returning to the reservoir. In the second case, the non-return means have the function of prohibiting any interference between the return pipes of the various sections. In both cases, there may be a single feeder line directly supplying all the valves and all the first supply inputs to the shutters.

 The invention will be clearly understood on reading the description which follows and with reference to the appended drawings in which.

Fig. 1 is a schematic rear view of an agricultural spraying machine comprising the supply system according to an embodiment of the invention;
Fig. 2 is, on a larger scale, a vertical section showing a shutter and its associated nozzle
Fig. 3 is an end view of a shutter assembly and its associated nozzle according to a variant;
Fig. 4 is a longitudinal section along the line
IV-IV of FIG. 3; and
Fig. 5 is a cross section of part of the
Fig. 4 along line VV.

 Schematically shown in FIG. 1 an agricultural spraying machine which comprises a chassis 1 and wheels 2 for moving on the ground 3. At the rear of the frame 1 is mounted a spraying boom which, in known manner, may include a central element 4 and , on each side, at least one lateral element or section 5. In the example, there are shown, on each side, two lateral elements 5.

 Each section or ramp element 4.5 comprises a support structure 6, shown in hatchings, on which are mounted a plurality of nozzle holders 7, each for a nozzle 8, single or multiple, suitable for projecting towards the ground 3 a jet 9 of sprayed liquid.

 The liquid to be sprayed comes from a reservoir 10 on the outlet pipe 11 from which is mounted a spray pump 12 which feeds, by a feeder pipe 13, all of the nozzle holders 7.

 Each nozzle holder 7 is constituted by a shutter which has a first inlet 14 for the spraying liquid, a second inlet 15 for controlling the outlet, an outlet 16 for supplying the nozzle 8 and movable means 17 for shutting off to put the first supply input 14 selectively in communication with the output 16 or out of communication with the latter.

 By way of illustration, only four nozzle holders 7 have been shown for each section or ramp element, but it is understood that, in practice, depending on the applications, each section may include a much larger number.

 Bypassing on the common feeder pipe 13, downstream of the last nozzle holder 7 of each section, a remote-controlled solenoid valve 18 is connected, the output of which feeds a return pipe 19 leading to the tank 10.

 Each valve 18 associated with a plurality of nozzle holders 7 is capable of occupying an at least partially closed position and an open position.

 Each return line 19 controls the associated plurality of nozzle holders 7 by the control inputs -15 thereof. Downstream of the last nozzle holder 7, the return pipe 19 carries a flow limiter 20 whose role will be described below. After the flow limiter 20, the return line 19, either, not shown; leads directly to the tank 10, or carries a non-return valve 21, the outlet of which is connected to a common collecting pipe 22 at low pressure returning to the tank 10.

 We will now describe, with reference to FIG. 2, a structure of the nozzle holders 7. These nozzle holders are for example of the type described in document FR-84 01449 to which reference may be made. In short, the nozzle holder 7 comprises a fixed body 23, internal channels 24, 25, one end of which leads respectively to the supply inlet 14 and to the outlet 16, a sealing chamber 26 which is in communication with the outlet 15 and with the other end of the channels 24,25, and the shutter means 17. The shutter means 17 consist of a piston 27 which is axially movable in the shutter chamber 26 and the two faces of which cooperate with membranes 28,29 d-have the periphery held by pinching on the body 23. The membrane 28 is turned towards the control input 15, while the membrane 29 is turned towards the inner end of the channels 24,25 which open out. in the sealing chamber 26 on a flat radial face of the body. As shown, the face of the piston on which, via the membrane 29, acts the liquid coming from the feed line 13 has an area smaller than that of the face of the piston on which acts, through the membrane 28, the liquid present in the return line 19. Thus, the shutter can be controlled in its closed position, which is that shown in FIG. 2, by a pressure in the return line which is lower than that prevailing in the feed line 13.

 The operation and use of the system described above will now be described. Assuming first of all that the valves 18 are in the closed position and of the type in which this closure is complete, that is to say that the flow to the return lines 19 is zero, the liquid to be sprayed. is routed only to the nozzle holders 7, the pistons 27 of which are pushed back into the open position for supplying all the nozzles 8 for spraying the liquid. The spray liquid, in this operating mode, is in permanent circulation, so that no deposits can be produced.

 If the valves 18 are of the type in which, for the so-called closed position, there nevertheless remains a certain flow of fluid, the liquid circulates at low pressure and at low flow rate in the return lines 19, to pass through the flow limiters 20 and the non-return valves 21 and finally reach the reservoir 10 via the common line 22. In this operating mode, the pressure prevailing in the return lines 19 is too low to command the closing of the pistons 27 which therefore remain in the fully open position.

 On the other hand, if part of the valves 18 are closed, the operation of the sections 4.5 associated with the other valves is not modified, whereas, for a section whose valve 18 has been opened, the pressure prevailing in the feeder line 13 is found almost entirely in the associated return pipe 19 due to the presence of the flow limiter 20 which is calculated to allow, at working pressure, only the passage of a flow corresponding to the total flow of the nozzles 8 of the associated section. Thus, in this return line 19, there is a relatively high pressure which, due to the differential nature of the piston 27, causes the latter to close, in the position shown in FIG. 2.

For this position, the outputs 16 are no longer supplied and, therefore, there is immediate interruption of spraying for the section concerned. For a section whose valve 18 is open, the circulation of the spraying liquid is carried out continuously from the feeder line 13 to the reservoir 10, passing through the valve 18, the return line 19, the flow limiter 20, the non-return valve 21 and the common return line 22.

 If all of the valves 18 are open, all of the pistons 27 are placed in the closed position, as indicated above, and all of the spray liquid discharged by the pump 12 into the feed line 13 returns to the reservoir. through the lines 19 and 22, still ensuring a continuous circulation of this liquid.

 There is shown in Figs. 3 to 5 a variant of the design and mounting of the nozzle holders.

By analogy with the embodiment of the
Fig 2, we adopted in Figs. 3 to 5, the same references for similar or functionally equivalent elements.

In the embodiment of Figs. 3 to 5, the feeder 13 and return 19 pipes are parallel and at the same level. At regular intervals, they directly carry the body 23 of the nozzle holders 7. The body 23 has, on the side of each pipe 13,19, a concave face 30,31 in which is housed the convexity of the corresponding pipe 13,19 . As shown on the
Fig. 5, the pipes 13,19 are drilled at regular intervals to receive, in a sealed manner, a tube 32,33 of. body 23, each tube being pierced to open on one side in the associated pipe 13,19 and, on the other side, in the sealing chamber 26. The channels formed in the tubes 32,33 define the inlet 14 for the liquid to be sprayed and the second shutter control inlet 15. In the chamber 26 also opens, on the same face as the channel 24, the channel 25 making the shutter chamber 26 communicate with the supply outlet 16 nozzles 8, this outlet 16 opening onto the horizontal lower face 34 of the body 23.

 Dans.la obturation chamber 26 are placed movable shutter means 17 which, as in the embodiment of FIG. 2 to the description of which reference may be made, comprise a differential piston 27 and two membranes 28 and 29.

 The body 23 of the nozzle holder 7 is firmly fixed on the pipes 13, 19 by a flange 38.

 As shown in Fig. 4, the body 23 carries a barrel 35 for supporting the nozzles 8, this barrel being ionised on the body by a bayonet system 36 and being able to rotate about a vertical axis 37 to selectively bring the nozzle 16 opposite the outlet 8 selected.

The arrangement of Figs. 3 to 5 has the advantage of mounting and structure of the nozzle holders in a small volume, the mounting being also particularly simple. Furthermore, the length of the outlet channel 25 is very reduced, which avoids the problems of drip after the obturation by the membrane 29. For the rest, the operation is identical to that of the embodiment of FIG. 2.
Of course, the invention is not limited to embodiments, nor to the mode of application, which have been described; on the contrary, we could conceive of various variants without departing from its framework.

Claims (13)

 1. Liquid supply system for a spraying boom comprising at least one section or boom element (4,5) carrying nozzles (8), a shutter (7) being associated with each nozzle and being of the type comprising a first supply inlet (14) for spraying liquid, a second control inlet (15) for spraying liquid, an outlet (16) for supplying the associated nozzle (8) and shutter means (17 ) to selectively put the first supply inlet (14) in communication or out of communication with the outlet (16), characterized in that it comprises a feed line (13) supplied with liquid to be sprayed from a tank (10) and a pump (12) and supplying successively the nozzles (8) of said section by their first supply inlet (14), a valve (18) mounted on the feeder pipe downstream of the shutter associated with the last nozzle of the section and suitable for occupying a position at least by partially closed and in an open position, and a return line (19) leading from the valve (18) to the reservoir (10) and successively controlling the shutters associated with the nozzles by their second control input (15), the whole being such that, depending on the position of the valve (8), the liquid to be sprayed, from the feeder line (13), is either directed at least partially towards the nozzles. (8) through the at least partially open shutters, or is directed completely back to the tank (10), through the return pipe which keeps the shutters in the closed position.  2. System according to claim 1, characterized in that the valve (8) has a position only partially closed to permanently maintain a circulation of the spray liquid in the return line and thus ensure continuous agitation.  3. System according to one of claims 1 and 2, characterized in that a flow limiter (20) is mounted on the return line (19), downstream of the shutter associated with the last nozzle, for maintain an active closing valve pressure in the return line when the valve is open.  4. System according to one of claims 1 to 3, characterized in that each shutter is of the differential type and comprises a piston (27 movable, on the opposite faces of which acts the pressure of the spraying liquid present in the feed line and in the return line.  5. System according to claim 4, characterized in that the area of the face of the piston on which the liquid from the feed line acts is less than the area of the face of the piston on which the liquid from the feed line acts return.  6. System according to one of claims 4 and 5, characterized in that a membrane (28,29) is interposed between each face of the piston and the spray liquid.  7. System according to one of claims 1 to 6, characterized in that it comprises at least two ramp elements, to each of which are associated a valve (18) and a pipe (19) for return to the tank.  8. System according to claim 7, characterized in that it comprises a single common feed pipe directly feeding the shutters on their first feed inlet (14), the valves (18) being mounted in bypass on the feed pipe.  9. System according to one of claims 7 and 8, characterized in that each section is associated with a clean return line leading directly to the tank without interfering with the other return lines.  10. System according to one of claims 7 and 8, characterized in that each return line (19) opens by a non-return valve (21.) in a single collector return line (22) returning to the tank.  11. System according to one of claims 1 to 10, characterized in that the body (23) of the shutter (7) is mounted between the feed line (13) and the return line (19), the body (23) having channels which open respectively inside said conduits, the body (23) having an outlet channel (25) which opens downwards.  12. System according to claim 11, characterized in that the feeder lines (13) and return (19) are in abutment. the body (23) of the nozzle holder.  13. System according to one of claims 11 and 12, characterized in that the body (23) of the nozzle holder (7) has a horizontal lower face (34) on which can slide a barrel- (35) suitable for bring one of the nozzles (8) in alignment with the spray outlet (16).