Abstract:
An agricultural sprayer including an induction unit capable of occupying at least one transport position and at least one filling position. A movement of the induction unit automatically predisposes a water circuit of the sprayer with a view to preparing a treatment spray mix. To do this, movement of the induction unit causes the opening or closure of at least one valve of the water circuit.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to the technical field of agricultural sprayers. It relates more particularly to a method for switching a water circuit with which such a machine is equipped, to allow said water circuit to be configured in the “induction” mode.  
           [0003]    Agricultural sprayers are used for spreading a treatment spray mix in the form of droplets onto plants. For this purpose, said sprayers include various elements connected to one another by a water circuit. These elements are, in particular, a main tank containing the spray mix, and spray nozzles intended to spread said spray mix over the plants that are to be treated. Spraying consists in pumping the spray mix, using the water circuit, from the main tank to the nozzles, while at the same time moving said nozzles with respect to the plants that are to be treated.  
           [0004]    Before actually carrying out the spraying, the user has, amongst other things, to prepare the treatment spray mix. Now, for obvious storage reasons, the active compound of the spray mix is generally packaged in the form of concentrate in cans. Preparing the spray mix therefore consists in diluting one or more active compounds, for example plant protection products, in water. To do this, and for user-safety reasons, most agricultural sprayers also include an induction unit. This may be fixed or moveable with respect to the sprayer and is preferably accessible from the ground. The induction unit is made up of a tub into which the user tips the cans of active compound. When preparing the spray mix, the tub is emptied into the main tank via the water circuit.  
           [0005]    After spraying, it is necessary to rinse all the elements which have been in contact with the treatment spray mix. This is because said spray mix tends, when it is stagnant, to form a deposit that is detrimental to the correct operation of said sprayer. To this end, most sprayers additionally include a reserve of water stored in a rinsing tank. Rinsing consists in pumping this reserve of water, via the water circuit, from said rinsing tank to the sullied elements. The spray mix residue, highly diluted in the rinsing water, is finally expelled onto said plants via the spray nozzles.  
           [0006]    In general, the water circuit of an agricultural sprayer also allows the main tank to be filled by pumping water from a river, for example. In addition it is common place for said water circuit also to allow said main tank to be emptied by transferring the treatment spray mix to an external tank.  
           [0007]    In order to perform the various functions listed hereinabove, the water circuit includes at least one pump, a set of pipes and several valves. In a way known to the person skilled in the art, the position of said valves determines the type of function performed by the water circuit (“spraying”, “induction”, “rinsing”, “filling”, “emptying”).  
           [0008]    2. Discussion of the Background  
           [0009]    With most agricultural sprayers currently on the market and in particular the sprayer described in patent application WO 95/03 688, the user configures the water circuit by manipulating each of the valves individually so as to position these valves in accordance with a layout corresponding to the desired function. Now, an agricultural sprayer generally has a great many valves, and each valve can be oriented into at least two different positions. Configuring such a water circuit, that the user changes each time there is a change in function, therefore constitutes a relatively great loss of time. In addition, with this type of manipulation, the risk of error in positioning the valves or quite simply the risk of forgetting to orient a valve, is not inconsiderable. In such an instance, the function performed by the water circuit is not the one desired by the user. The consequence of this may, for example, be loss of said active compound.  
           [0010]    In order to solve this problem, patent application FR 2,714,572 describes an agricultural sprayer in which some valves of the water circuit are operated by a control unit. With this known sprayer, the user first of all selects the function that is to be performed, by means of a selector. Then, the control element electrically drives various valves of the water circuit so as to configure the latter in the appropriate mode. However, the use of such a solution probably leads to a not insignificant manufacturing on-cost. In addition, this solution still entails the intervention of the user, for example when preparing the treatment spray mix, to indicate the type of function to be performed. In consequence, the risks of error are not eliminated. For example, the user may forget to select the “induction” function. He may just as easily select the wrong function.  
         SUMMARY OF THE INVENTION  
         [0011]    The object of the present invention is therefore to remedy the various drawbacks of the state of the art by proposing a solution for an agricultural sprayer comprising a moving induction unit, so as to eliminate any risk of oversight and error in manipulation when configuring the water circuit in the “induction” mode.  
           [0012]    Accordingly, there is proposed a method for switching the configuration of a water circuit of an agricultural sprayer to “induction” mode, said sprayer including an induction unit capable of occupying at least one transport position and at least one filling position, wherein a movement of said induction unit from a transport position into a filling position switches the configuration of said water circuit to the “induction” mode. With agricultural sprayers including a moving induction unit and when preparing the spray mix, the user brings the induction unit into a filling position so as to make it easier to tip the cans of active compound. With the switching method of the present invention, this action prior to any induction has the effect of automatically, and therefore quickly, configuring the water circuit of the sprayer for the appropriate function. As the user no longer operates said valves manually, the risk of oversight and errors of manipulation are therefore eliminated.  
           [0013]    The present invention also relates to an agricultural sprayer for implementing this switching method. Said sprayer therefore includes a moving induction unit and a water circuit configured by valves. According to another feature of the present invention, the movement of the induction unit acts directly on the valves involved in configuring the water circuit in the “induction” mode. In consequence, the means for implementing the method of the present invention are simple and therefore inexpensive. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    Other features of the invention will also become apparent from the other subclaims and from the following description of one nonlimiting exemplary embodiment of the invention depicted in the appended drawings, in which:  
         [0015]    [0015]FIG. 1 depicts, in a side view and during transport, an agricultural sprayer according to the invention,  
         [0016]    [0016]FIG. 2 is a diagram of a water circuit equipping the agricultural sprayer of FIG. 1, said water circuit being configured in the “spraying” mode,  
         [0017]    [0017]FIG. 3 is a diagram of the water circuit equipping the agricultural sprayer of FIG. 1, said water circuit being configured in the “tank rinsing” mode,  
         [0018]    [0018]FIG. 4 is a diagram of the water circuit equipping the agricultural sprayer of FIG. 1, said water circuit being configured in the “boom rinsing” mode,  
         [0019]    [0019]FIG. 5 is a diagram of the water circuit equipping the agricultural sprayer of FIG. 1, said water circuit being configured in the “filling” mode,  
         [0020]    [0020]FIG. 6 is a diagram of the water circuit equipping the agricultural sprayer of FIG. 1, said water circuit being configured in the “emptying” mode,  
         [0021]    [0021]FIG. 7 is a diagram of the water circuit equipping the agricultural sprayer of FIG. 1, said water circuit being configured in the “induction” mode,  
         [0022]    [0022]FIG. 8 depicts, viewed in the direction of arrow I defined in FIG. 1, an induction unit equipping the agricultural sprayer of FIG. 1, said induction unit being in the transport position,  
         [0023]    [0023]FIG. 9 depicts, also viewed in the direction of arrow I, the induction unit in the filling position,  
         [0024]    [0024]FIG. 10 depicts, viewed in the direction of arrow II defined in FIG. 8, the induction unit being in the transport position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    [0025]FIG. 1 depicts an agricultural sprayer  1  according to the invention, in the transport position. Said sprayer  1  includes a chassis  2  which runs along the ground by means of two wheels  3 . Said chassis  2  supports, on one hand, a main tank  4  containing a treatment spray mix  5  and, on another hand, several spray nozzles  6  arranged at substantially uniform intervals along a spray boom  7 . Said chassis  2  is connected, in a known way, to a motor vehicle (not depicted) by means of a drawbar  8 . Said motor vehicle trails said sprayer  1  in a direction of forward travel  9 . In this exemplary embodiment, said sprayer  1  is therefore of the trailed type. It goes without saying that the present invention relates also to sprayers of the mounted type and to self-propelled sprayers.  
         [0026]    During work, said agricultural sprayer  1  is moved over a field containing plants that are to be treated. Said spray boom  7  is arranged transversely to said direction of forward travel  9 , on each side of a vertical mid-plane of said sprayer  1 . Said spray boom  7  is connected to said chassis  2  by means of a connecting device  10 . The spray height of said nozzles  6  can thus be adapted to suit the taller or shorter height of the plants that are to be treated. For further information about said connecting device  10 , those skilled in the art may refer to the U.S. application registered under the No. 09/808,168. For its part, said treatment spray mix  5  is pumped, by means of a water circuit  11 , from the main tank  4  to be deposited, by virtue of said spray nozzles  6 , on said plants.  
         [0027]    Aside from the “spraying” function described hereinabove, said water circuit  11  is also called upon to carry out other functions, for example: “filling”, “induction”, “rinsing” and “emptying”. For this purpose, in the exemplary embodiment depicted in FIGS.  2  to  7 , said water circuit  11  includes, in particular, a pump  12 , a set of pipes and several valves. In a way known to those skilled in the art, the position of said valves determines the type of function carried out by said water circuit  11 . In a way also known to those skilled in the art, said pump  12  is driven in rotation by means of a universally-jointed transmission shaft  13 , by the power take-off (not depicted) of said motor vehicle. The various other functions listed above will be described later on.  
         [0028]    As visible in FIG. 1, said agricultural sprayer  1  additionally includes an induction unit  14 . The role and embodiment of said induction unit  14  will also be described later.  
         [0029]    For reasons of clarity, said set of pipes and said valves are not shown in FIG. 1.  
         [0030]    [0030]FIG. 2 schematically depicts an exemplary embodiment of a water circuit  11  with which the agricultural sprayer  1  of FIG. 1 may be equipped. Said water circuit  11  includes a first selector valve  15  arranged upstream of said pump  12 . This first selector valve  15  allows the user to select the source from which said pump  12  is fed. For this purpose, said first selector valve  15  has three inlet ports  15 A,  15 B,  15 C and one outlet port  15 D. Said outlet port  15 D of said first selector valve  15  is connected to the intake orifice  16  of said pump  12  by means of a first pipe  17 . The first inlet port  15 A is connected to a first external connector  19  by means of a second pipe  20 . Said first external connector  19  advantageously allows said water circuit  11  to be fed from a source external to said sprayer  1 . The second inlet port  15 B is connected to a drain  21  arranged at the lowermost point of said main tank  4  (depicted in section in FIGS.  2  to  7 ) by means of a third pipe  22 . For its part, the third inlet port  15 C is connected to a second drain  23 , this time arranged at the lowermost point of a rinsing tank  24 , by means of a fourth pipe  25 . Said rinsing tank  24  will be described later.  
         [0031]    Said water circuit  11  also includes a second selector valve  26  arranged downstream of said pump  12 . This second selector valve  26  allows the user to choose the destination of the fluid delivered by said pump  12 . For this purpose, said second selector valve  26  includes, for its part, four outlet ports  26 A,  26 B,  26 C,  26 D and one inlet port  26 E. Said inlet port  26 E of said second selector valve  26  is connected to the delivery orifice  27  of said pump  12  by means of a fifth pipe  28 . The first outlet port  26 A is connected to a second external connector  29  by means of a sixth pipe  30 . Said second external connector  29  advantageously makes it possible to transfer the contents of the main tank  4  into a tank external to said sprayer  1 . The second outlet port  26 B is connected to a rinsing device  31  for rinsing said main tank  4 , by means of a seventh pipe  32 . Said rinsing device  31  will be described later on. The third outlet port  26 C is connected to a distribution device  33  by means of an eighth pipe  34 . Said distribution device  33  will also be described later on. For its part, the fourth outlet port  26 D of said second selector valve  26 , is connected to said main tank  4  by means of a ninth pipe  35 .  
         [0032]    In the exemplary embodiment depicted in FIGS.  2  to  7 , said water circuit  11  also includes a filter  18  connected to said first pipe  17 . Said filter  18 , arranged therefore between said first selector valve  15  and said pump  12 , is intended to protect said pump  12  against any impurities that might be present in the fluid sucked up. Said first pipe  17  therefore has two portions  17   a,    17   b.  The first portion  17   a  connects said first selector valve  15  to said filter  18 . For its part, the second section  17   b  connects said filter  18  to said pump  12 .  
         [0033]    In the exemplary embodiment depicted in FIGS.  2  to  7 , each selector valve  15 ,  26  also has a respective handle  36 ,  37 . Thus, said handle  36  allows the user, in the case of said first selector valve  15 , to place one of said inlet ports  15 A,  15 B,  15 C in communication with said outlet port  15 D. For its part, said handle  37  allows the user, in the case of said second selector valve  26 , to place said inlet port  26 E in communication with one of said outlet ports  26 A,  26 B,  26 C,  26 D.  
         [0034]    In FIGS.  2  to  7 , each arrow on a pipe indicates the direction of flow of the fluid inside said pipe. No arrow on a pipe, on another hand, indicates that said pipe does not convey fluid in the function under consideration.  
         [0035]    [0035]FIG. 2 more particularly depicts the water circuit  11  configured in the “spraying” mode. During work, this function is used to deposit said treatment spray mix  5  in the form of droplets on the plants that are to be treated.  
         [0036]    To do this, the user, on one hand, by means of said first selector valve  15 , places the intake orifice  16  of said pump  12  in communication with the drain  21  of said main tank  4 . On another hand, the user, by means of said second selector valve  26 , places the delivery orifice  27  of said pump  12  in communication with said distribution device  33 .  
         [0037]    In a way known to those skilled in the art, said distribution device  33  makes it possible to adjust and to regulate the amount of treatment spray mix  5  deposited on said plants. In a way also known to those skilled in the art, said spray nozzles  6  are advantageously grouped together in sections  36 . Thus, by cutting the supply of spray mix  5  to one or more sections  36 , the user can adapt the working width of the sprayer  1 . The surplus treatment spray mix  5  arriving from said pump  12  and not distributed to the various nozzles  6  is returned to said main tank  4  by means of a tenth pipe  37 .  
         [0038]    [0038]FIGS. 3 and 4 depict the water circuit  11  of FIG. 2 configured this time in the “rinsing” mode. This function is generally used once spraying is finished. This is because when said treatment spray mix  5  lies stagnant for a certain period of time, it tends to form a deposit which is detrimental to the correct operation of said water circuit  11 . To avoid this deposit, it is necessary to rinse all the elements which have been in contact with said spray mix  5 . In a way known to those skilled in the art, the agricultural sprayer  1  for this purpose has a rinsing tank  24 . Said rinsing tank  24  (not depicted in FIG. 1) is able to store a reserve of water. During rinsing, this reserve of water circulates through all the sullied elements. Finally, the treatment spray mix  5  residue, highly diluted in the rinsing water, is expelled through said spray nozzles  6 .  
         [0039]    [0039]FIG. 3 more particularly depicts a configuration of said water circuit  11  that makes it possible to rinse said main tank  4 . To do this, the user on one hand, by means of said first selector valve  15 , places the intake orifice  16  of said pump  12  in communication with the drain  23  of said rinsing tank  24 . On another hand, by means of said second selector valve  26 , the user places the delivery orifice  27  of said pump  12  in communication with said rinsing device  31 . In a way known to those skilled in the art, said rinsing device  31  is made up of several rinsing nozzles  38 . Said rinsing nozzles  38  are intended to hose down the interior walls of said main tank  4  with the water contained in the rinsing tank  24 . For reasons of clarity, only two rinsing nozzles  38  have been depicted in FIGS.  2  to  7 . It goes without saying that in actual fact the entirety of the interior walls of the main tank  4  is reached by the jet from said rinsing nozzles  38 .  
         [0040]    To finish rinsing said agricultural sprayer  1 , the user then configures said water circuit  11  into the “boom rinsing” mode as depicted in FIG. 4. This function this time allows the water contained in the rinsing tank  24  to be pumped and circulated in particular through the pipe  34 , the distribution device  33 , the tenth pipe  61  and said spray nozzles  6 . To do this, the user on one hand, by means of said first selector valve  15 , places the intake orifice  16  of said pump  12  in communication with the drain  23  of said rinsing tank  24 . On another hand, the user, by means of said second selector valve  26 , places the delivery orifice  27  of said pump  12  in communication with said distribution device  33 .  
         [0041]    The “suction” function depicted in FIG. 5 allows the user to fill said main tank  4  from an external source. Thus, by connecting said first external connector  19  to a strainer  39 , the user can advantageously draw water from a river. To do this, the user, on one hand, by means of said first selector valve  15 , places the intake orifice  16  of said pump  12  in communication with said first external connector  19 . On another hand, by means of said second selector valve  26 , the user places the delivery orifice  27  of said pump  12  in communication with said main tank  4 .  
         [0042]    By contrast, the “emptying” function depicted in FIG. 6 allows the user to transfer the contents of said main tank  4  to an external tank (not depicted). Having connected said external tank to said second external connector  29 , the user, on one hand, by means of said first selector valve  15 , places the intake orifice  16  of said pump  12  in communication with the drain  21  of said main tank  4 . On another hand, by means of said second selector valve  26 , the user places the delivery orifice  27  of said pump  12  in communication with said second external connector  29 .  
         [0043]    Before actually carrying out spraying, the user has to prepare the treatment spray mix  5 . This is because for obvious storage reasons, the active compound for the spray mix  5  is generally packaged in the form of concentrate in cans. Preparing the spray mix  5  therefore consists in diluting one or more active compounds, for example plant protection products, in water. To do this, said agricultural sprayer  1  includes an induction unit  14 . Said induction unit  14  is made up of a tub  40  into which the user tips the cans of active compound. When preparing said spray mix  5 , said tub  40  is emptied via the water circuit  11  into the main tank  4 . Said induction unit  14  is advantageously moveable with respect to said sprayer  1 . It may thus occupy a transport position (FIGS. 1, 8 and  10 ) or a filling position (FIG. 9).  
         [0044]    It will be noted that for reasons of clarity, said set of pipes of said water circuit  11  does not appear in FIGS.  8  to  10 .  
         [0045]    In the exemplary embodiment depicted in FIGS.  8  to  10 , said tub  40  is supported by a framework  41 . For its part, said framework  41  is connected to said chassis  2  by means of an articulated arm  42 . Said articulated arm  42  is produced in the form of a parallelogram  43  made up of an upper rod  44  and of a lower rod  45 . Said rods  44 ,  45  are connected, on one hand, to said chassis  2  by means of a respective articulation  44 A,  45 A and, on another hand, to said framework  41  by means of a respective articulation  44 B,  45 B. Said articulations  44 A,  45 A,  44 B,  45 B are advantageously of the pivot type, the respective axes of which are substantially mutually parallel. Said parallelogram  43  extends in a plane of extension that is substantially vertical, and the angular travel of the lower rod  45  about the articulation  45 A is delimited by two stops  46 ,  47 .  
         [0046]    Said articulated arm  42  advantageously additionally includes a tension spring  48  connected, on one hand, to said chassis  2  and, on another hand, to said lower rod  45 . Said tension spring  48  makes it possible, on one hand, to keep said induction unit  14  in the transport position by pressing said lower rod  45  against the upper stop  46 . On another hand, said tension spring  48  also makes said induction unit  14  easier to move from the filling position to the transport position by taking at least some of the weight of said induction unit  14 . However, the anchoring points of said tension spring  48  are advantageously determined so that in the filling position, said lower rod  45  rests against the lower stop  47  in spite of the force exerted by the tension spring  48 . Said induction unit  14  can thus easily be translated from a transport position which, amongst other things, makes the spraying operations easier (FIGS. 1, 8 and  10 ), to a filling position making access to said tub  40  easier (FIG. 9), and vice versa.  
         [0047]    According to the exemplary embodiment depicted in FIGS.  8  to  10 , the user initiates the emptying of said induction unit  14  by acting on a pedal  49 , said pedal  49  in turn actuating an emptying valve  50  (FIG. 9). More specifically, in the light of FIGS.  2  to  10 , said emptying valve  50  is connected between the bottom of said tub  40  and the intake orifice  51 A of an injector  51  (not depicted in FIGS.  8  to  10 ). The role of said injector  51  will be specified later on.  
         [0048]    In this exemplary embodiment, said pedal  49  and said emptying valve  50  advantageously constitute a safety element preventing any accidental return of fluid into said tub  40 . What happens is that, when the user is not acting on said pedal  49 , the latter automatically keeps said emptying valve  50  in the closed position. For further details about the operation of said emptying valve  50  those skilled in the art can refer to U.S. application No. 09/899,154.  
         [0049]    According to one feature of the present invention, a movement of said induction unit  14  from a transport position into a filling position switches the configuration of said water circuit to the “induction” mode. In addition, according to another feature of the present invention, a movement of said induction unit  14  from a filling position to a transport position cancels said configuration in the “induction” mode. Said water circuit  11  therefore reverts to the configuration used beforehand.  
         [0050]    For this purpose, in the exemplary embodiment depicted in FIGS.  2  to  7 , said water circuit  11  additionally includes two shut-off valves  52 ,  53 . Said first shut-off valve  52  is inserted between said pump  12  and said second selector valve  26 . Said fifth pipe  28  is therefore made up of two portions  28   a ,  28   b . The first portion  28   a  connects said delivery orifice  27  of said pump  12  to said first shut-off valve  52 . The second portion  28   b,  for its part, connects said first shut-off valve  52  to said inlet port  26 E of said second selector valve  26 . For its part, said second shut-off valve  53  is inserted between said pump  12  and said injector  51 . Thus, said second shut-off valve  53  is connected, on one hand, to the delivery orifice  27  of said pump  12 , by means of an eleventh pipe  54 . On another hand, said second shut-off valve  53  is connected to the inlet orifice  51 B of said injector  51  by means of a twelfth pipe  55 . Said injector  51  also has an outlet orifice  51 C connected to said main tank  4  by means of a thirteenth pipe  56 .  
         [0051]    In the exemplary embodiment depicted in FIGS.  2  to  7 , said eleventh pipe  54  is not directly connected to the delivery orifice  27  of said pump  12 . What happens is that said eleventh pipe  54  is advantageously connected to said first section  28   a  of said fifth pipe  28 . Likewise, said thirteenth pipe  56  is not directly connected to said main tank  4 . What happens is that said thirteenth pipe  56  is connected to said ninth pipe  35 . That advantageously makes it possible to reduce the length of said pipes  54 ,  56  and therefore to reduce the costs of manufacture of said water circuit  11 .  
         [0052]    According to the exemplary embodiment depicted in FIGS.  8  to  10 , said shut-off valves  52 ,  53  respectively include a body  57 ,  58  and an operating rod  59 ,  60 . In a way known to those skilled in the art, rotating said operating rod  59 ,  60  causes said corresponding shut-off valve  52 ,  53  to open or to close.  
         [0053]    In the light of FIG. 10, said operating rods  59 ,  60  are advantageously connected to said articulation  45 A. As said articulation  45 A is itself connected in terms of rotation to said lower rod  45 , movement of said induction unit  14  thus causes said shut-off valves  52 ,  53  to open or to close. For its part, the respective body  57 ,  58  of each shut-off valve  52 ,  53  is advantageously connected to said chassis  2 . Preferably, said shut-off valves  52 ,  53  are arranged in close proximity to said articulation  45 A. As a result, said operating rods  59 ,  60  can be connected directly to said articulation  45 A.  
         [0054]    According to the exemplary embodiment depicted in the figures, said shut-off valves  52 ,  53  are two identical valves mounted top to toe at a respective end of said articulation  45 A (FIG. 10). As a result, said shut-off valves  52 ,  53  are advantageously arranged in such a way that a movement of said induction unit  14  on one hand causes one of said shut-off valves  52 ,  53  to open and on another hand causes the other of said shut-off valves  52 ,  53  to close.  
         [0055]    More specifically, when said induction unit  14  is in the filling position (FIG. 9), said first shut-off valve  52  is closed and said second shut-off valve  53  is open. In consequence, when referring to FIG. 7 in which said water circuit  11  is configured in the “induction” mode, all of the fluid delivered by said pump  12  is directed toward said main tank  4  through said injector  51 . In a way known to those skilled in the art, the circulation of a fluid through the inlet orifice  51 B of said injector  51  causes a depression at said intake orifice  51 A. Thus, when the user operates said pedal  49 , the contents of said tub  40  are emptied into said main tank  4 . As said first shut-off valve  52  is closed, the configuration of said water circuit  11  in the “induction” mode therefore does not depend on the position of said second selector valve  26 . Likewise, executing the “induction” function is independent of the position of said first selector valve  15 . The user can thus advantageously empty the contents of said tub  40  by pumping the water initially contained in the main tank  4  (FIG. 7) or pumping the water originating from an external source (FIG. 5) or even using the water from the rinsing tank (FIGS. 3, 4). The movement of said induction unit  14  into the filling position therefore automatically causes said water circuit  11  to configure itself in the “induction” mode.  
         [0056]    By contrast, when said induction unit  14  is in the transport position (FIGS. 1, 8 and  10 ), said first shut-off valve  52  is open and said second shut-off valve  53  is closed. In consequence, all of the fluid delivered by said pump  12  is directed toward said second selector valve  26 . The “filling”, “spraying”, “rinsing” and “emptying” functions therefore take place as described previously. Likewise, the type of function executed by said water circuit  11  once again depends on the position of said selector valves  15 ,  26 . Moving said induction unit  14  into the transport position therefore automatically causes the configuration of said water circuit  11  in the “induction” mode to be canceled.  
         [0057]    The water circuit  11  and the agricultural sprayer  1  which have just been described are merely examples which must not in any case be taken to limit the field of protection defined by the claims which follow.  
         [0058]    Specifically, said shut-off valves  52 ,  53  and said eleventh pipe  54  may be replaced by a third selector valve (not depicted) having one inlet port and two outlet ports. Said inlet port is connected to said first section  28   a , a first outlet port is connected to said second section  28   b , and the second outlet port is connected to said twelfth pipe  55 . The operating rod of said third selector valve also being connected to said articulation  45 A, the movement of said induction unit  14  places said pump  12  in communication either with said second selector valve  26  or with said injector  51 .  
         [0059]    The switching method which is the subject of the present invention can also be applied to a water circuit in which the valves are driven by a control unit. As said control unit is informed of the movement of said induction unit by means of a sensor, it can configure said water circuit accordingly.