Abstract:
The present invention relates to an agricultural sprayer the chassis of which comprises a bearing structure intended to support a storage device and a connecting structure intended to support a spreading device. The sprayer is notable in that the bearing structure comprises a single stringer. The present invention advantageously reduces the cost of manufacture of the sprayer.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the general technical field of agricultural machinery and more specifically to a sprayer the chassis of which comprises a bearing structure intended to support a storage device and a connecting structure intended to support a spreading device. 
   2. Discussion of the Background 
   Such a chassis is known to those skilled in the art. Indeed, document FR 2 520 586 describes an agricultural sprayer the chassis of which is intended to support a tank for plant protection product. To do this, said chassis comprises a frame arranged in a substantially horizontal plane. This frame is made, in an entirely typical way, using two stringers connected to one another by crossbeams. This known chassis also comprises two uprights intended to support a spray boom. Said uprights, welded to the rear of a respective stringer, are arranged vertically. 
   This known chassis does, however, have the drawback of being relatively lengthy and expensive to manufacture. Indeed, to obtain the frame and the connecting structure, it is necessary first of all to fashion a relatively large number of elements (stringers, crossbeams, uprights, etc). These various elements then have to be assembled with particular care in order to guarantee that it will be easy to mount said storage device and said spreading device on said chassis. 
   SUMMARY OF THE INVENTION 
   The object of the present invention consists in overcoming this drawback of the state of the art by proposing a sprayer of simplified design and which is less expensive to manufacture. 
   To this end, the sprayer of the present invention is one wherein said bearing structure comprises a single stringer. The manufacture of such a bearing structure therefore entails the production of just one element. Said chassis is therefore much less expensive and time-consuming to manufacture. 
   According to another feature of the present invention, said connecting structure advantageously comprises a single upright. This makes it possible to reduce the cost of manufacture of said chassis even further. 
   According to an additional feature of the present invention, said chassis rests at least partially on the ground by means of a ground-connection device. As a preference, said ground-connection device comprises a suspension intended to damp the jolts caused by the movement of said sprayer over uneven terrain. To this end, said suspension comprises an active element comprising an elastically deformable member and a damper. Still with a view to reducing the cost of manufacture, said active element advantageously requires just one anchoring point on said chassis. 
   Sprayers of the trailed type comprise a hitching head intended to connect said chassis to a tractor vehicle. During maneuvers, said tractor vehicle and said sprayer are articulated, in a way known to those skilled in the art, about a vertical axis passing through said hitching head. Relatively large angular travel about said vertical axis guarantees good manoeuvrability. To this end, it is known practice in the state of the art for said hitching head to be connected to said chassis by means of a hitching boom. Said hitching boom advantageously allows the relatively wide elements of said sprayer (chassis, tank) to be kept away from the area in which, during said pivoting, the rear wheel of said tractor vehicle in particular moves. According to another feature of the present invention, said hitching device advantageously comprises a hitching head connected directly to said chassis. The sprayer of the present invention thus saves on said hitching boom. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features of the invention, which are to be considered separately or in any possible combination, will become further apparent from the following description of one non limiting exemplary embodiment of the invention which is depicted in the appended drawings in which: 
       FIG. 1  depicts, in a side view, an agricultural sprayer according to the invention, 
       FIG. 2  depicts, in a view from above and on a different scale, the chassis of the sprayer of  FIG. 1 , 
       FIG. 3  depicts, in a side view and with part sections and on another scale, the chassis of FIG.  2 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  depicts, in a side view, an agricultural sprayer  1  according to the present invention. During work or during transport, said sprayer  1  is moved along in a direction and sense of travel indicated by the arrow  2 . In the remainder of the description, the ideas of “forward” and “back”, “in front of” and “behind” are defined with respect to the direction of forward travel  2 , and the ideas of “right” and “left” are defined when looking at said sprayer  1  from the rear in the direction of forward travel  2 . 
   In a way known to those skilled in the art, said sprayer  1  is used to spread a treatment liquid, for example a fertilizer or a plant protection product, over plants and/or over the ground  3 . To this end, said sprayer  1  comprises a storage device  4  intended to contain, among other things, said treatment product. Said sprayer  1  additionally comprises a spreading device  5  intended to spread said product substantially uniformly over a working width. Said storage device  4  and said spreading device  5  are supported by a chassis  6 . To do this, said chassis  6  comprises respectively a bearing structure  7  and a connecting structure  8 . In the case of sprayers of the mounted type, said chassis  6  is designed to be supported by the three-point hitch of a carrier vehicle (not depicted). By contrast, in the case of trailed or self-propelled sprayers, said chassis  6  rests at least partially on the ground  3  by means of a ground-connection device  9 . 
   In the exemplary embodiment depicted in  FIG. 1 , said storage device  4  comprises a main tank  10  intended to contain said treatment liquid. Said main tank  10  is advantageously arranged on each side of a vertical mid-plane  11  of said sprayer  1 . For purposes of clarity, said main tank  10  has not been depicted in  FIGS. 2 and 3 . 
   According to an important feature of the present invention, said tank  10  is supported by a single stringer  12 . As a preference, said stringer  12  is arranged under said tank  10  and at least substantially in said vertical mid-plane  11 . In the light of  FIG. 3 , said stringer  12  is advantageously made using a substantially straight hollow section piece. Said section piece, a tube of square cross section in the example depicted, makes it possible to obtain a bearing structure  7  which is robust and relatively lightweight while at the same time being inexpensive to manufacture. 
   In a way known to those skilled in the art, said chassis  6  also comprises a superstructure  13  intended, among other things, to hold said tank  10  on said stringer  12 . According to another exemplary embodiment, not depicted, said storage device  4  may also comprise one or more secondary tanks intended, for example, to contain a rinsing liquid. Said secondary tanks are supported either directly by said stringer  12  or via said superstructure  13 . In any event, as said superstructure  13  is connected to said stringer  12 , all of the weight of said storage device  4  rests on said stringer  12 . As it is known to those skilled in the art and for reasons of clarity, said superstructure  13  has not been depicted in  FIGS. 2 and 3 . 
   For its part, said spreading device  5  comprises, in the exemplary embodiment visible in the figures, a boom  14  supporting a multiplicity of spray nozzles (not depicted). During work, said boom  14  is deployed, transversely to said direction of forward travel  2 , on each side of said sprayer  1 . Said nozzles are intended to spray said treatment liquid uniformly over the plants and/or over the ground  3 . During transport, as depicted in  FIG. 1 , said boom  14  is advantageously folded so as to reduce the size of said sprayer  1 . As a preference, during transport, said boom  14  rests at least partially on said superstructure  13 . As said boom  14  is known per se, it has been depicted only in FIG.  1  and then symbolically. 
   In a way known to those skilled in the art, said spreading device  5  also comprises a connecting member  15  intended to connect said boom  14  to said chassis  6 . During work, said connecting member  15  has, in particular, to keep said boom  14  parallel to said ground  3 . Advantageously, said connecting member  15  also makes it possible, for example according to the size of the plants that are to be treated, to alter the distance separating said spray nozzles from said ground  3 . In the exemplary embodiment depicted in the figures, this modification of the spraying height is achieved by means of a deformable-parallelogram system. 
   According to another feature of the present invention, said connecting member  15  is connected to a single upright  16  of said chassis  6 . As a preference, said upright  16  lies at least substantially in said vertical mid-plane  11  and at the rear of said sprayer  1 . As can be seen in  FIG. 3  which depicts a view in section of said chassis  6 , said upright  16  is made using two substantially vertical side plates  17  connected by two closure sheets  18 . Said upright  16  thus has a box structure perfectly suited to withstanding the stresses generated by said spreading device  5 . 
   In the exemplary embodiment depicted in the figures, said system with a parallelogram advantageously comprises a single parallelogram  19 . In  FIG. 3 , said upright  16  has three openings  20 ,  21 ,  22  defining the respective axes of three articulations  23 ,  24 ,  25 . Said articulations  23 ,  24  respectively allow the connecting of an upper arm  26  and of a bottom arm  27  of said parallelogram  19  to said upright  16 . For its part, said articulation  25  allows a ram  28  to be connected to said upright  16 . In a way known to those skilled in the art, said ram  28  is intended to deform said parallelogram  19  and thus move said boom  14  in a substantially vertical direction. 
   In the exemplary embodiment depicted in the figures, said sprayer  1  is of the trailed type. Said chassis  6  therefore rests at least partially on the ground  3  by means of said ground-connection device  9 . In addition, said chassis  6  is connected to a tractor vehicle (not depicted) by means of a hitching device  29 . 
   In a way known to those skilled in the art, said ground-connection device  9  comprises at least two wheels  30  arranged one on each side of said vertical mid-plane  11 . In a particularly advantageous way, said wheels  30  are connected to said chassis  6  by means of a suspension  31  making it possible to damp out jolts generated by the movement of said sprayer  1  over uneven terrain. 
   In the exemplary embodiment depicted in the figures, said suspension  31  comprises a trailed arm  32  connected to said chassis  6  by means of an articulation  33  the axis of which is at least substantially horizontal and perpendicular to said direction of forward travel  2 . Said articulation  33  is advantageously arranged in said vertical mid-plane  11 . As a preference, said trailed arm  32  is connected to said side plates  17 . As visible in particular in  FIG. 3 , said suspension  31  also comprises an active element  34  making it possible to damp the pivoting of said trailed arm  32  relative to said chassis  6  about said articulation  33 . In a way known to those skilled in the art, said active element  34  comprises an elastically deformable member and a damper. 
   According to another feature of the present invention, said active element  34  requires just one anchoring point  35  on said chassis  6 . 
   In effect, in the exemplary embodiment depicted more specifically in  FIG. 3 , said active element  34  is made of a single oleopneumatic ram  36  connected, on one hand, to said chassis  6  and, on another hand, to said trailed arm  32 . In a particularly advantageous way, said anchoring point  35  of said oleopneumatic ram  36  to said chassis  6  lies inside said stringer  12 . Said oleopneumatic ram  36  comprises an adjustable energy accumulator  41  and an adjustable restriction  42 . Thus, the stiffness and damping of said suspension  31  can easily be adapted to suit the weight of said sprayer  1 . As said oleopneumatic ram  36  is known per se, it will not be described further. 
   For its part, and in a way known to those skilled in the art, said hitching device  29  comprises a hitching head  37 . In the exemplary embodiment depicted in the figures, said hitching head  37  is produced by means of a ring  38  intended to fit into a hook (not depicted) of said tractor vehicle. 
   According to another feature of the present invention, said hitching head  37  is connected directly to said chassis  6  and more specifically to said stringer  12 . 
   Being relatively narrow and arranged in said vertical mid-plane  11 , said stringer  12  also fulfils the function devolved upon the hitching booms of the prior art, namely that of allowing a relatively large amount of angular travel between said tractor vehicle and said sprayer  1 . As a preference, said hitching head  37  is connected to said stringer  12  by means of an articulation  39  the axis of which is substantially horizontal and perpendicular to said direction of forward travel  2 . Advantageously, the pivoting of said hitching head  37  with respect to said stringer  12  about said articulation  39  is damped by means of damping elements  40 . Said damping elements  40  are advantageously arranged inside said stringer  12 . 
   The chassis  6  and the agricultural sprayer  1  which have just been described are just one exemplary embodiment and example of use which must not in any way be taken as limiting the field of protection defined by the claims which follow. 
   Thus, the mechanism for moving said boom  14  closer to or further away from said ground  3  may also be produced by means of a sliding connection of substantially vertical axis. 
   In addition, said hitching head  37  may have a totally different design to the one depicted. Specifically, it may be produced using a cradle intended to be connected to the lower arms (not depicted) of a three-point hitch of said tractor vehicle.