Abstract:
Sprayer boom beam structure includes a girder member having an elongated profiled sheet structure including at least two folds or bends defining three portions in an inverted V- or U- or C-shaped cross-section, i.e. a pair of side or wing walls integrally joined by a top or bridge wall. Triangular orifices are punched out of the side walls, alongside one another in a longitudinal direction, alternating between inverted and upright triangles, leaving inclined strips of sheet material in between, and which absorb and transmit strains and stresses similar to a tubular lattice structure, and having benefits of a spatial lattice-like structure. Complementary beam members include a base plate joining longitudinal edges of sidewalls of the profiled member and close the open face of the profiled member, forming a sturdy box-like structure, and internal cross-platelets joined to inclined strips of the profiled-member sidewalls to further rigidify the beam structure.

Description:
CROSS-REFERENCE OF RELATED APPLICATIONS  
       [0001]     This application claims priority of Argentine patent application no. P 05 01 00962, filed Jun. 9, 2005, and this application claims priority of Argentine patent application no. P 05 01 00962, filed on Mar. 11, 2005, and each of which is incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The present invention is related in general to farming machinery, more particularly to boom structures on sprayer machines.  
       BACKGROUND OF THE INVENTION  
       [0003]     Sprayer machines carry booms mounting a number of spray nozzles at regular intervals thereon for applying fertilizers, herbicides and the like on crops. The purpose of these beams is proper positioning of the spraying nozzles. Productivity is enhanced using booms on the order of about 25 to 30 meters across, sometimes more for large tracts of farmland. For constructive, operational and practical reasons, the booms are built in sections or modules in the form of beams joined together by hinge elements which enable folding the booms so as to avoid obstacles, like fences and windmills, make a tight turn or put the machine away.  
         [0004]     To achieve their purpose, a boom structure must be designed and built to withstand bending-moment strains generated by weight distributed along the length of its structure, including that of its nozzles and accessory elements, without undue vertical or horizontal deformation thereof. A typical 25- or 30-meter boom may be made up of three beams on each side of the machine. The inner beam must be particularly strong enough to withstand the overall weight of its structure and load and that of other beams joined to its distant (outer) end. Hence, structural weight is a major factor in boom design and construction.  
         [0005]     As in many fields of engineering, the classical solution to the weight and strength (mechanical resistance) dilemma is tubular spatial-lattice structures. Thus, the beams for sprayer booms currently found on the market comprise spatial (3-dimensional) lattice structures made of tubular steel members having square o rectangular cross-sections, wherein the ends of the members are welded together forming isosceles triangles, with the vertex between like sides pointing downwards. US patent publication No. 2002/0113137 contains an example of this kind of lattice structure.  
         [0006]     The above-mentioned triangular lattice structure meets many mechanical requirements such as stability and resistance to the high stresses generated by such boom lengths. However, its construction requires substantial manpower and time. For instance, a typical boom 25 meters long may have between 40 and 100 tubular members, which have to be welded to one another after sawing off the two ends thereof at an angle. Furthermore, because of the weight constraints the walls of the tubular members should be as thin as possible. Welding generates residual strains in the tubular walls which may break during service.  
         [0007]     Repair is likewise cumbersome and expensive. Since the beam is a welded unit, in many cases the structure has to be completely replaced even when damage is restricted to just a part thereof.  
         [0008]     There are also examples teaching away from the lattice-type structure and therefore less labour-intensive to manufacture. Argentine patent (AR) No. 246,684 also available as Brazilian patent (BR) No. 9500654, to Favot (of Cruz Alta, Córdoba, Argentina) discloses a boom comprising left- and right-hand bar or tubular members spanning 28 meters. The members are of constant section with tubular walls 2 mm thick. The boom weighs about 150 kg resulting in a substantial bending moment at the near end, this being a critical zone where the weld may eventually crystallize, leading to breakage.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0009]     An object of the present invention is to facilitate construction of beams for agricultural sprayer booms strong enough to resist strains and stresses to which the structures are subjected during normal operation.  
         [0010]     Another object of the present invention is to provide a boom beam structure that is not weakened by welding points. And a related object is to enable a beam to be built using other, unweldable materials.  
         [0011]     Yet another object of the present invention is to facilitate repair and maintenance of boom beams.  
         [0012]     Yet a further object of the present invention is to enable automation of the construction of boom beams using tools and means available on the market.  
         [0013]     The sprayer boom beam structure of the present invention comprises a girder member produced in an elongated profiled sheet structure having at least two folds or bends that define three portions in an inverted V- or U- or C-shaped cross-section, i.e. a pair of side or wing walls integrally joined by a top or bridge wall. Triangular orifices are previously punched out of the side walls, alongside one another in a longitudinal direction and alternating between inverted and upright (non-inverted) triangles so as to leave inclined strips of the sheet material integrated in between which absorb and transmit strains and stresses in a like fashion to the typical tubular lattice structure, thereby maintaining the abovementioned benefits of a spatial lattice-like structure.  
         [0014]     Complementary beam members include a base plate joining the longitudinal edges of the sidewalls of the profiled member so as to close the open face of the profiled member and form a sturdy box-like structure, and internal cross-platelets joined to the inclined strips of the profiled-member sidewalls to further stabilize (rigidize) the beam structure. The platelets, being inclined to the longitudinal direction of the boom, become thus a functional part of these strips in transmitting strains and stresses throughout the beam structure resulting from intrinsic (weight and bending moment) and extrinsic (e.g. wind, jerks, collisions, etc.) factors. Removable fastener elements such as bolts and nuts, rivets or screws may be used to join the baseplate and the cross-platelets to the profiled member. This eliminates the need of welding and consequential local weak points in addition to simplifying construction and reducing manpower in relation to the forementioned welded tubular structure.  
         [0015]     The height of the side walls advantageously decreases outwardly (i.e. away from the machine) and, likewise, the triangular orifices get gradually smaller. A particular feature of the invention is that the fold lines in the sheet structure are not parallel but slightly offset such that they virtually converge at a point off the beam. This feature facilitates use of a suitable standard folding machine for bending a metal sheet along the fold lines to form the girder of the beam structure. As a result, the shape of the bridge wall is not strictly rectangular but trapeze in fact, gradually broadening in the longitudinal direction away from the machine, i.e. towards the distant end of the beam.  
         [0016]     As a member of a multibeam boom, the beam structure is supplemented with removable end caps provided with pivot or hinge elements for connecting outer boom beams to inner beams and the innermost beams to an agricultural machine structure. Preferably, the caps are made of the same metal or plastics material as the other beam components.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The above-stated and other novel features and aspects of this invention and how it may be reduced to practice may be better understood from the detailed description hereinafter of a preferred embodiment shown in the attached drawings, wherein:  
         [0018]      FIG. 1  is a perspective view of a boom for mounting to one side of a sprayer machine and comprising three hinged beams or sections illustrated in a partially folded position.  
         [0019]      FIG. 2  is an exploded view of the innermost beam of  FIG. 1 , according to a preferred embodiment of the present invention.  
         [0020]      FIG. 3  is a side view, broken in the middle, of the girder member of the beam of  FIG. 2 , according to a preferred embodiment of the present invention.  
         [0021]      FIG. 4A  is a cross-section through the middle of the beam of  FIG. 2 .  FIGS. 4B, 4C  and  4 D are cross-sections analogous to  FIG. 4A  but illustrating alternative beam embodiments.  
         [0022]      FIG. 5  is a top plan view of the base plate of the beam of  FIG. 2 .  
         [0023]      FIG. 6  is a plan view of a steel sheet prior to holding to make the folded girder member of  FIG. 3 .  
         [0024]      FIG. 7  is an elevational view of the base plate of  FIG. 5  showing some of the sprayer units and piping mounted thereon.  
         [0025]      FIG. 8A  is a plan view of and  FIG. 8B  a medial cross-section through an internal cross-platelet used for reinforcing the beam of  FIG. 2 .  
         [0026]      FIGS. 9A and 9B  are enlarged, respective side-elevation and top-plan views of the articulation in  FIG. 1  between the end-caps of the middle and inner boom beams in an extended position. The end-cap of the inner boom beam is partially cut away in  FIG. 9A  to show part of the mechanism for folding the middle and outer boom beams.  FIG. 9C  is an end view of the articulation of  FIGS. 9A and 9B  in a fully folded or non-operational position.  
         [0027]      FIGS. 9A and 9B  are enlarged, respective side-elevation and top-plan views of the articulation in  FIG. 1  between the end-caps of the middle and inner boom beams in an extended position. The end-cap of the inner boom beam is partially cut away in  FIG. 9A  to show part of the mechanism for folding the inner and middle boom beams.  FIG. 9C  is an end view of the articulation of  FIGS. 9A and 9B  in a fully folded or non-operational position.  
         [0028]      FIG. 10A  is an enlarged view of the articulation in  FIG. 1  between the end-caps of the middle and outer boom beams.  FIG. 10B  is a view from below of the articulation of  FIG. 10A  in a slightly yielding position.  
         [0029]      FIG. 11  is a perspective view of the boom end mounted to a tractor.  
     
    
       [0030]     Like numerals in different figures refer to like or equivalent elements.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     A boom according to a preferred embodiment of the invention is illustrated in  FIG. 1 . Two such booms are mounted, one to each side, of a sprayer machine (not illustrated) having an overall operational spray width of 25 meters and carrying a tank for 3,200 liters of spray solution. The boom comprises three beams  10 - 10 ′- 10 ″ extending end to end in a longitudinal direction X (the longitudinal direction X of the boom corresponds to the cross-machine direction of the sprayer machine) when the boom is in its unfolded position (which is not the case in  FIG. 1 ). The two innermost beams  10 - 10 ′ comprise elongated structures according to the present invention, although the dimensions of the middle beam  10 ′ are on a reduced scale in relation to the innermost beam  10  of the two. An inner cap  12  is mounted to the near end of the innermost beam  10  and is provided with hinge element  14  for mounting the boom to the sprayer machine. An outer cap  16  is mounted to the distant end of the innermost beam  10  and is provided with hinge element  18  described in further detail hereinafter for attachment to an end cap  12 ′ of the middle beam  10 ′ in order to pivotably connect the two innermost beams  10 - 10 ′. Finally, the middle beam  10 ′ has an outer cap  16 ′ mounted to its distant end for pivotably attaching the outermost beam  10 ″ of the boom via a fifth cap  12 ″ as also described in further detail hereinafter.  
         [0032]     The outermost beam  10 ″ need not have a lattice-like structure as the two innermost beams  10 - 10 ′ since its load is obviously on a much lesser scale. In the preferred embodiment, the innermost beam  10  weighs about 120 kg in all, the middle beam  10 ′ about 30 kg and the outermost beam  10 ″ around 18 kg.  
         [0033]     The entire structure of the innermost beam  10  is illustrated in  FIG. 2 . The main structural member or girder of the beam  10  is an elongated sheet structure  20  illustrated in  FIG. 3  with main fold lines  22  having a tall trapeze-like cross-section resembling a “V” shape as illustrated in  FIG. 4A , with a pair of generally identical front and rear (in relation to the machine travel direction) sidewalls  24  depending downwards from a narrow horizontal top wall or spine  26 . In the preferred embodiment, the top fold  22  is a little less than a right-angle, opening gradually down along the beam, and each sidewall  24  has a complementary, much slighter fold  28  such that the overall fold  22 - 28  on to each side is 90°. The open side or bottom of the girder structure  20  is closed by a base plate  30  illustrated in  FIG. 5 , thereby forming a closed box-like structure  20 - 30  conveying structural stability to the boom beam  10 .  
         [0034]     The cross-section of the girder member  20  illustrated in  FIG. 4A  is not constant over the entire length of the member  20  but rather continuously varies in size and in its aspect ratios (i.e. minor-base:major-base and height:major-base) along the longitudinal direction X, increasing very gradually breadthwise along the top  26  and decreasing in height at a somewhat greater rate from the inner end (i.e. nearest to the sprayer machine) to the outer or distant end of the beam  10 , the major base of the cross-section remaining constant throughout the longitudinal direction X. In other words, the sidewalls  24  are tallest and the spine  26  narrowest at the inner edge. In the preferred embodiment, the sheet is 2½ millimeters thick and the girder  20  is about 6½ meters long, 50 centimeters high at the inner end and 36 centimeters high at the outer end. The decrease in height is an obvious design choice to reduce overall weight since section weight and bending moment loads decrease towards the distant end of the boom away from the sprayer machine but the simultaneous increase in width down along the longitudinal direction X has to do with the folding process when manufacturing the girder member  20  as described further on herein. Referring back to  FIGS. 2 and 4 A, the bottom edges  24  of the girder sheet  20  are again folded inwards along longitudinal fold lines  32 , providing ledges  24  for the baseplate  30  to bear on and to reinforce these edges  24  against collisions against external objects.  
         [0035]     Referring now to  FIG. 6 , the girder member  20  is manufactured from a flat sheet  20 ′. Because of the just described cross-section variations, the starting shape of the sheet  20 ′ is not a rectangle but an irregular pentagon resembling the shape of an approximately isosceles trapeze with an indented major base  34 . The steel sheet is cut by die-cutting, guillotine, plasma, laser or waterjet into the starting shape  20 ′. Before folding, triangular orifices  36  are punched out of the side walls of the sheet  20 ′ one after the other leaving inclined strips  38  in between. The triangles  36  are isosceles right-angled triangles such that the strips  38  are inclined at 45° to the longitudinal edges  24  of the girder  20 . The sheet  20 ′ is then folded twice along lines  32  to form the inturned edges  24 , then slightly along lines  28  and finally along the inner lines  22  to form the top wall  26  of the girder  20 . The top pair of fold lines  22  converge on an imaginary point on the axis of symmetry X way off the major base of the sheet  20 ′ (corresponding to the inner or near end of the beam  10 ) and the remaining pairs of fold lines  28  and  32  converge on an opposite imaginary point off the minor base of the sheet  20 ′ (corresponding to the distant end of the beam  10 ).  
         [0036]     The baseplate  30  is manufactured from a flat rectangular sheet in which rectangular orifices  40  are punched alongside one another in the longitudinal direction X leaving bridges  42  of sheet material in between. Both the triangular orifices  36  in the girder member  20  of  FIG. 3  and the rectangular orifices  40  in the baseplate  30  of  FIG. 5  serve to lighten the beam structure  20  and will later resemble the lattice-like structure apparent in  FIG. 2 . The starting sheet for the baseplate  30  is then folded six times along parallel fold lines  44 ,  46  and  48  extending in the longitudinal direction X so as to nestle inside the bottom portion of the girder member  20 , as illustrated in  FIG. 4A .  
         [0037]     In addition to structurally strengthening and stabilizing the girder structure  20 , the base plate  30  also serves to support thirteen nozzle holders  50  along the boom and to carry plastic piping  52  for supplying liquid fertilizers, herbicides, insecticides and the like to the nozzle holders  50 . The sprayers are preferably three-nozzle ¼″ (one-quarter inch) diameter nozzle holders  50  which are placed through the baseplate orifices  40  as shown in  FIG. 7 . Supports  54  are affixed to the bridges  42  for mounting the pipes  52 .  
         [0038]     A salient feature of the invention is that the structural members  20  and  30  are mounted to one another using bolts and nuts or other removable securing elements such as rivets for instance. To this end, round holes  56  are drilled or otherwise punched out at predetermined positions on the members  20 ,  30  prior to the folding process thereof. Some of the round holds  56  may be circular and others oblong-shaped in order to ease mating holes matching each other and passing the bolts  58  or rivets therethrough.  
         [0039]     It is acknowledged that the baseplate would optimize rigidity and stability if it were mounted upside-down from the position illustrated in  FIG. 4A , however the illustrated mounting is preferred since the nozzle holders  50 , particularly the active nozzles thereof, are protected in this way by the lower strip  64  of the girder sidewall  24  and the inturned edge  32 . In order to compensate for this protective arrangement and at the same time enhance rigidity and stability, bar-shaped spacer units  62  straddle the lower strips  64 ,  66  of the girder and baseplate members  20 - 30 . Threaded holes  68  are drilled at each end of the spacers for affixing in place using the same bolts  58  as for joining the latter members  20 - 30 . More particularly, the spacers  62  are omitted at the positions of the nozzle holders  50 , preferably alternating two spacers  62  to a nozzle holder  50 .  
         [0040]     Stability of the inner beam  10  is further supplemented by a plurality of cross-platelet members  70  illustrated in  FIGS. 8A and 8B , mounted at regular intervals (coinciding with the girder strips  38 ) inside the girder member  20 . As in the cases of the elongated girder members  20  and  30 , the cross-platelets  70  are folded sheet parts, generally trapeze-shaped and dimensioned to fit snugly inside the girder cross-section. The side edges  72  thereof are folded back at right-angles to provide ear surfaces for joining to the girder member  20 . The sizes of the platelet members  70  differ from one another, the larger of the platelets  70  being mounted to the sidewalls  24  towards the inner end of the girder  20  and the shorter platelets  70  towards the outer end thereof. Oval-shaped holes  74  are punched out to lessen the weight contribution, at least in the larger platelets  70 . Round circular and matching oblong holes  56  are drilled or punched out of the folded-back edges  72  of the platelets  70  and the inclined strips  38  of the girder sidewall  24  for bolting  58  the platelets  70  to the sidewalls  24 . Finally, the top and bottom ends of the platelet are recessed inwards  78  to make room for the passage of piping  52  and assorted wiring and the like.  
         [0041]     The middle boom beam  10 ′ is designed with the same structure as the above-described inner beam  10  except on a smaller scale with otherwise similar girder and baseplate members since the bending moment load is much less. For this reason, sheet only 1/16′ thick is used and the cross-platelets  70  in the larger beam  10  may be left out of the middle beam  10 ′. On the other hand, as illustrated in  FIG. 1 , the outermost beam  10 ″ may be manufactured in a more simplified folded-sheet structure.  
         [0042]     All the end-caps  12 ,  12 ′,  16 ,  16 ′ are also manufactured by folded metal sheets. Sheet 3/16″ thick is used for the pair of caps  12 ,  16  on the inner beam  10  and ⅛″ thick for the caps  12 ′,  16 ′ on the middle beam  10 ′. Round and oblong holes  56  for bolts  58  are drilled or punched out at predetermined positions on the members  12 ,  16 ,  12 ′ and  16 ′ prior to the folding process thereof. Generally conventional articulations on the end-caps allow the outstanding boom section or beam to be purposely pulled up to fold the boom, such as when the sprayer machine is taken out of service for instance or, as the case may be, to yield and be automatically pushed back by an obstacle encountered in operation, such as when turning around near a fence for instance, to avoid damaging the boom. In the illustrated embodiment, the articulation  12 ′- 16  between the larger beams  10 ,  10 ′ folds up and back vertically whereas the articulation  16 ′- 12 ″ yields backwards horizontally.  
         [0043]      FIGS. 9A, 9B  and  9 C illustrate two articulated end-caps  16  and  12 ′ which are mounted to the outer and inner ends, respectively of the inner and middle beam beams  10 - 10 ′. The end-caps  16  and  12 ′ are interconnected via a pull-up articulation consisting of a metal shaft  80  extending through respective pairs of ears  82 ,  82 ′ projecting from the tops of each beam  10 - 10 ′. The articulation shaft may comprise a bolt  80  passing through the inner and the outer ears  82 - 82 ′ and secured by a nut  84  in a way in which the ears  82 - 82 ′ pivot when the middle beam  10 ′ is turned upwards by a partially toothed gear-wheel  86  mounted on the same shaft  80  driven by a toothed rack  88  extending lengthwise inside the girder  20 . The rack  88  may be remotely driven by a hydraulic cylinder  90  mounted inside the girder  20  and connected to further piping (not illustrated) extending inside the top of the inner beam  10 .  
         [0044]     The ears  82 ′ of the end-cap  12 ′ of the middle beam  10 ′ are placed inwards of the pair of ears  82  of the end-cap  12  of the inner beam  10 . A tubular sleeve  92  is mounted coaxial to the shaft  80  and welded to the toothed wheel  86  and, at each end thereof to the pair of ears  82 ′ so that the latter is turned upwards when the rack  88  is pushed outwards by an increase in hydraulic pressure in the cylinder  90 , thereby folding the middle beam  10 ′ about the shaft  80 , together with the outer beam  10 ″ at the end thereof, to lie on top of the inner beam  10 ′, in the position shown in  FIG. 9C . Conversely, when the rack  88  is pulled back towards the cylinder  90 , the wheel  86  is turned the other way and the middle and outer beams  10 ′- 10 ″ unfold back into their extended operational positions. Stops  94 ,  94 ′ are welded at the bottom of each cap  12 ′,  16  in order abut when the boom is in its fully extended, operational position. Respective rubber caps  96  cover the ends of the stops  94 ,  94 ′ to dampen contact and noise when they come together.  
         [0045]      FIGS. 10A and 10B  illustrate two end-caps  16 ′ and  12 ″ which are mounted to the outer and inner ends, respectively, of the middle and outer boom beams  10 ′- 10 ″. The push-back articulation is a ball  98  and socket  100  joint mounted at the bottom of the respective beam ends. A spring  102  projecting half-way up from the inner beam  10  returns the outer beam(s) to the normal extended position once it has been released by the obstacle. A stub  104  extends inside the spring and abuts against a stop  94 ″ when the boom is fully extended and operational.  
         [0046]     The innermost end-cap  12  illustrated in  FIGS. 1 and 2  serves to mount the boom to the front of the sprayer machine in a generally conventional fashion. As illustrated in  FIG. 11 , the end-cap  12  includes a cross-arm  106  having a proximal pivot  14  mounted to the tractor vehicle chassis (not illustrated) in a conventional fashion and distant offset pivot  108  articulated to the piston shaft  110  of a hydraulic cylinder  112  for moving the boom about the hinge  14  between its respective operative and folded-back positions.  
         [0047]     All girder  20 , baseplate  30 , cross-platelet  70  and end-cap  12 ,  12 ′,  16 ,  16 ′ members of both beam beams  10 - 10 ′ are manufactured from SAE 1010. The members  12 ,  16 ,  20 ,  30  and  70  may be painted or subjected to other surface treatment processes, such as steel galvanization for example, prior to mounting.  
         [0048]     Of course, changes, variations and aggregations may be made to any of the above-detailed embodiments, without departing from the scope of the invention. The same has been described by way of preferred embodiments, however those skilled in the art may suit it to other applications or introduce modifications without departing from the purview of the invention as set forth in the appended claims. For instance, while steel sheets are used in the preferred embodiment, the teachings herein may be adapted and applied to other materials, such as fiberglass or carbon reinforced plastics and the like, for which other cross-sections may be suitable. Another possible material is aluminum or an alloy thereof; the reason aluminum is not used typically for boom structures is its unsuitability for welding, however the present invention does away with practically all welding and aluminum is light, thereby relaxing bending moment loads along the cross-sections of the structure and stresses on the sprayer machine.  
         [0049]     Furthermore,  FIGS. 4B, 4C  and  4 D illustrate alternative “U”-shaped cross sections and  FIG. 4E  a “C”-shaped cross-section for embodying the girder and baseplate members  20 ,  30  with folded sheet structures. In  FIG. 4B  the sidewall  24 ′ is formed by a single, rounded 90° fold  22 ′.  FIG. 4C  illustrates an open girder structure  20 ″ made from thicker sheet material with no baseplate, wherein the sprayers may be mounted depending from the underside of the top wall  26 ′. Whereas the fold lines  22  and  28  are not parallel in the V-shaped girder member  20  only illustrated in  FIG. 4A  as specified hereinbefore, parallel fold lines would be provided for alternative booms having a U- or a C-shaped cross-section of  FIGS. 4B  to  4 E.  
         [0050]     While this invention has been described as having a preferred design, it is understood that it is capable of further modifications, and uses and/or adaptations of the invention and following in general the principle of the invention and including such departures from the present disclosure as come within the known or customary practice in the art to which the invention pertains, and as may be applied to the central features hereinbefore set forth, and fall within the scope of the invention or limits of the claims appended hereto.