CROP-SPRAYING APPARATUS

Abstract: A device (10) for spraying liquid onto a crop with the assistance of directed air streams. Air is impelled into a central air chamber (22), through left and right hollow swivelling joints (33, 34) along extended air booms (13, 14) to pass out through outlet funnels (35). Associated with each outlet funnel (35) is a spray nozzle (19) which directs spray liquid into the outgoing air stream. The extended booms (13, 14) can be pivoted to a trailing position behind the device. The flattened outlet funnels (35) together with the positioning of the nozzles (19) provide an enhanced, directed atomised spray.

Description: CROP-SPRAYING APPARATUS - 1 - The invention relates to crop-spraying apparatus and has particular, but not exclusive, reference to apparatus for spraying ground crops with the assistance of directed air streams. Such apparatus may be mounted on a trailer to be towed, mounted directly on the rear of a tractor, or otherwise conveyed over the crops to be sprayed. The apparatus may be used for spraying crops with water, fertilizer, insecticide, weedicide, or other agricultural chemicals. It is well known in the art to construct crop-spraying machines with extended booms or frames which carry a series of spray outlets. The booms or frames are generally only structural members which support separate spray systems, although a conduit for spray fluid may form one element of a cantilevered framework, and an extended boom may itself be the conduit for spray fluid. It is clearly desirable for these extended booms or frames to have a broad span, to allow for greater coverage for each pass of the machine, while providing for the span to be reduced to facilitate transportation and storage of the equipment. A number of configurations have been proposed with booms or frames of broad span in an extended state, and with provision for these extended members to be folded or collapsed on several joints, or swung inward from the extended state on a single pivot. U.S. Patent 3807676 discloses an arrangement for booms mounted on a spray vehicle to act as supports for a separate spray system. Booms extend from either side of a vehicle, being pivotally mounted to a rack on the rear of the vehicle. The boom may be swung forward from the transverse, extended spraying position to a stowed position parallel to the vehicle by means of hydraulic rams. In British Patent 1425162, a spray line is housed within a channel member forming part of a framework extending either side of a central mounting rack. The extended frameworks are universally jointed to the rack to -allow them to swing to a limited extent in the vertical plane parallel to their extension, providing for a span suitable for sloping terrain, and to allow them to swing slightly rearwardly and upwardly on striking an obstruction. The frameworks are articulated on horizontal axes to allow their outer sections to pivot upwards for transportation and storage. Loop portions of flexible spray line are included to allow the spray line to bend at these articulations. In British Patent 1435999, booms which act as conduits of spray fluid extend either side of a trailer and are supported by wheels mounted on their outboard ends. The booms are articulated on vertical axes at several points along their lengths and at their join to the trailer. The sections of the spray booms are coupled at each articulation by flexible hose to allow the booms to be folded in parallel with the trailer in a compact storage mode. British Patents 2110062 and 2149271 both disclose a boom assembly mounted at the rear or a vehicle with extended side sections pivotally connected to a central section directly behind the vehicle. The assembly is collapsed or folded by means of double-acting hydraulic rams connected between the side and centre sections pivoting the side sections inwardly and upwardly to a stored position. The spray fluid is conducted to each section by a flexible tube. In British Patent 210096, the booms are cantilevered latticework girders, made of resin and glass fibre, and articulated as a number of vertical axes. The spray fluid is conveyed through a flexible manifold mounted on each boom. In West German Patent 3321615, a field spraying device is disclosed which has extended members in the form of metal trusses. The trusses support liquid lines leading to spaced spray nozzles. To enable the trusses to be collapsed for transportation and storage, they are articulated on vertical pivots, allowing the end portions to be folded in. At the articulation points, the liquid line passes from one portion of the trusses to the next by a length of flexible tubing. This patent relates specifically to a pivoting joint which surrounds and supports this flexible length so that it twists when the trusses are folded, but does not buckle, thus reducing wear. It has been found that this form of articulation to allow extended booms to be folded in is unnecessarily complex and limited in application. It is also known in the art to enhance the efficiency of spraying plants by coupling an air blower to the spraying system to produce a stream of atomised spray fluid. This is particularly prevalent in applications such as spraying orchards when greater projection of spray fluid is required. Recently, the use of a forced-air mist of spray fluid has been found to be effective in spraying ground crops, especially those with dense foliage. Conventional spraying tends only to deliver spray fluid to the outer layer of foliage. When the spray fluid is carried by a stream of air, the air-blast agitates the foliage and forces the spray fluid to penetrate further. The combined effect of this agitation and the greater penetration is a considerably enhanced coverage of the entire crop, and this method particularly enhances penetration down to the base of the crop. Droplets of spray may also be swept back upwards from the ground level in the air turbulance to cover the underside of a crop's leaves. In a known crop-spraying configuration of this type, a number of individual flexible air hoses lead from a central fan housing to spray nozzles spaced along extended booms. The spray nozzles are situated in the centre of circular air outlets at the end of each hose, so that fluid leaving the nozzles is atomised and enveloped within a conical air stream, producing the enhanced misting effect. In this configuration, it has been found that the connection of air hoses from the central air blower to the air outlets is unnecessarily complex, costly and cumbersome. The means of delivery of spray fluid into the air stream in this configuration can be unsuitable for ground crops. The use of flexible air hoses severely limits the air pressure which can be developed to assist spraying, and the volume of air passing through the outlets is unduly limited. It is also difficult or impossible to adjust the height of the spray outlets from the ground to cater for different heights and widths of crops. This system does not provide an even distribution of spray across the width of the spray band. A circular spray pattern means that foliage in the centre of the spray band beneath the nozzle receives considerably more spray fluid than foliage on either side. As a circular spray passes across the ground, it is clear that the amount of spray delivered will fall off according to the transverse distance from the central longitudinal diameter of the circle. The effect of this is that foliage in the centre of each spray band may receive a wasteful excess of spray fluid, whereas foliage on either side may receive deficient amounts. Usage of spray fluid would clearly be optimised by a more even distribution of fluid across each band of spray. Another such configuration has large flexible cylindrical air bags filled by a central air impeller and suspended from extended booms on either side of a support vehicle. Beneath the air bags are spray lines with spaced spray nozzles. Air outlets on the underside of the air bags allow a general downwards turbulent flow which carries the spray fluid with it. It has been found that the device is not of sufficiently sturdy construction. The air bag system is structurally inadequate and prone to wear, and does not allow for high air pressures. It is only suitable for producing a general downward flow in the form of a curtain of air. It cannot provide a controlled, directed air stream associated with each spray nozzle. The effect is to produce a broad, turbulent mist of spray which is unsuitable for crops with dense foliage and uneconomical and wasteful for crops in discrete, spaced rows. According to the present invention, there is provided a crop-spraying apparatus comprising an air impeller, a central air chamber to receive air from the air impeller, a pair of hollow air booms positioned either side of the air chamber and each communicating with the air chamber via a respective hollow joint, a plurality of air outlets along each boom, a spray outlet associated with each air outlet, and means for supplying spray fluid to each spray outlet, whereby air impelled by the impeller into the air chamber passes through the joints, along the booms, and out the air outlets to assist in the delivery of spray fluid from the spray outlets to the crop. Preferably, the hollow joints are adapted to allow the booms to swing between extended positions transverse to, and stored positions parallel to the forward direction of travel of the apparatus, and to allow the booms to be set in intermediate positions between the extended and stored positions. Each air outlet is preferably shaped to provide a directed air stream substantially normal to the extended booms, with a downwards and forward component. In order that the present invention may be more fully understood, two particular embodiments of the invention will be described with reference to the accompanying drawings in which: Figure 1 is a general perspective view of a crop-spraying device in accordance with the invention; Figure 2 is a cross-sectional view along line II-II of Figure 1; Figure 3a is a partial plan view of the device in Figure 1 shown with booms in fully extended position; Figure 3b is a partial plan view of the device in Figure 1 shown with booms in intermediate position; Figure 4 is a rear view of the device in Figure 1; Figure 5 is a rear view of a second crop-spraying device in accordance with the invention; Figure 6 is a partial cross-sectional view of the right-hand joint of the first crop-spraying device along the line VI-VI in the direction indicated in Fig 1; and Figure 7 is a partial cross-sectional view of the right-hand joint of the second crop-spraying device, analogous to Fig. 6. Like reference numerals in the drawings indicate like components. Figure 1 shows the general configuration of a first crop-spraying device 10. The apparatus is mounted on a trailer 15 to be towed by a tractor in the direction indicated. A tank 11 for the spray fluid is connected to a pump 16 driven through a drive shaft 17 by the tractor's power take-off (not shown). Flexible reinforced rubber pipes 18 take the spray fluid from the pump 16 to a series of conventional spray nozzles 19. At the rear of the trailer 15 is a tangential air impeller 12 of radius approximately 50cm and with its downwardly directed outlet 21 directly connected to a central air distribution chamber 22 extending transversely across the width of the trailer 15. The centrifugal air impeller 12 is driven by a drive shaft (not shown) passing beneath the tank 11 and connected to the tractor's power take-off. Alternatively, the air impeller may be driven by a dedicated petrol motor. It has been found that in this embodiment approximately 50 h.p. is required to produce a desirable air flow at a pressure of approximately 25 inches (water gauge), with the air impeller blade running at approximately 3000 rpm. The chamber 22 has three air outlet ports 30, 31 and 32, the central outlet port 31 leading directly to a central air outlet duct 35, and the outlet ports 30 and 32 at either end of the chamber 22 leading to the extended air booms 13 and 14 via pivoting hollow joints 33 and 34. The air booms 13 and 14 carry a number of air outlet ducts 35. Each air outlet duct 35 has a flattened conical air funnel 36, with a spray nozzle 19 mounted on the upper flat face of each funnel 36. The booms 13 and 14 are partially supported by struts 71 and 72 respectively, connected to cylindrical cups 73 and 74 which fit over cylindrical stems 75 and 76 so that the cups may turn freely on the stems, thus allowing the struts 71 and 72 to swing in concert with the booms 13 and 14. The booms 13 and 14 are swung on the joints 33 and 34 by means of double-acting hydraulic rams 80 and 81 pivotally connected both to the air chamber 22 and to extended legs 83 and 84 projecting from upper, pivoting portions of the joints 33 and 34. When the rams 80 and 81 are connected to the tractor's hydraulic system (not shown), they can drive the booms 13 and 14 either individually or together to swing on the joints 33 and 34 between the fully extended spraying position shown in Figures 1 and 3a and a trailing, stowed position with the booms projecting rearwardly of the trailer. The stowed configuration enables the apparatus to pass through gates and narrow spaces and along public roads, and facilitates storage. The tractor operator can also swing the booms in this fashion to avoid obstacles in the path of the extended booms. Moreover, the booms 13 and 14 may be set by the hydraulic rams at intermediate positions, at an acute angle to the fully extended position. Fig. 3b shows a typical intermediate setting. A comparison of Figs. 3a and 3b illustrates the use of such an intermediate setting. At the fully-extended position in Fig. 3a, the apparatus is adapted to spray a crop sown in rows the same distance apart as the spacing of spray nozzles and air outlets along the booms (dimension X in Fig. 3a). When the rams 80 and 81 are partially contracted, the booms 13 and 14 are set in an intermediate position such as is shown in Fig 3b. The effective spacing of the spray nozzles is reduced as the boom is swung inward, according to the cosine of the angle of the boom's deflection from its fully extended position (so that dimension Y in Fig 3b is equal to X multiplied by the cosine of the angle of deflection.) In this way, the operator can set the boom according to the row spacing of the crop to be sprayed. When the apparatus is to be used on crops sown various distances apart, it may be appropriate to provide for the wheelbase of the trailer 15 to be adjustable according to the spacing apart of crop rows. The construction of the right-hand joint 34 is shown in detail in Fig.6. The left-hand joint 33 is constructed analogously. A hollow cylindrical stem 30 leads upwards from the air outlet port 32 in the air distribution chamber 22. An annular flange 41 with an upturned edge 42 is fitted to the outside of the stem 30. The stem 30 terminates in a projecting rim 48. An elbow section 50 leads from the air boom 14 to a cylindrical section 49 which fits tightly around the projecting rim 48 and is provided with an annular flange 43 corresponding with the first flange 41. An annular disc 44 fits over the top of the flange 43 and within the upturned edge 42. Intermediate packing layers in the form of fibreglass matting 45 and 46 are placed between the disc 44 and flange 43, and between flanges 43 and 41. These packing layers facilitate the movement of the flanges 43 relative to the flange 41 and disc 44. Bolts 47 pass through corresponding holes in disc 44 and flange 41 outside the circumference of flange 43, and nuts are screwed onto the bolts to hold the joint assembly 34 together. The nuts are tightened sufficiently to ensure structural rigidity and to minimise leakage of air through the joint, while allowing the central flange 43 to turn freely within the joint. The hollow construction allows air to pass through the joint from the air chamber 22 to the air boom 14, while the free movement of the flange 43 allows the boom 14 to swivel in a horizontal plane. Cylindrical spacers (not shown) may be positioned on the bolts 47 so as to turn freely and thus minimise any wearing effect of contact between the central turning flange 43 and the fixed bolts 47. Fig. 2 illustrates the atomising effect of the spray of fluid meeting the forced air stream from an air outlet 35. The flattened funnel of the outlet projects downwardly and forwardly in a plane normal to the extended position of the boom. The spray nozzle 19 is mounted on the flat upper face of the air funnel. A spray nozzle is selected to provide an even fan-shaped spray subtending an angle of 110° . In an alternative configuration, a spray nozzle is used which produces a fan spray of 80° . A stream of air passing from the air boom leaves the outlet funnel in a directed downward and forward flow with sufficient pressure to agitate the crop's foliage and to penetrate to the base of the crop. The introduction of the spray of fluid into the air stream from above maximises the amount of spray carried by the directed air stream to ensure that the spray fluid fully penetrates the crop. The combination of the fan-shaped spray of fluid with the air stream created by the outlet funnel 36 provides a broad spray of fluid of even distribution across its width. In a preferred construction (not shown in drawings) the air outlet funnel 36 can be detached from the air outlet duct 35, and a cylindrical extension member inserted to bring the outlet funnel 36 and its associated spray nozzle 19 closer to the ground. This provides for a narrower band of spray fluid, and allows for an economical use of fluid particularly when crops are young, being small in size and close to the ground. Extensions may be provided in various lengths to enable a range of spray band widths to be covered by the one spraying apparatus. Alternatively, an extension facility is provided by including telescoping segments of the outlet duct 35 which can be set at various extensions by wingnuts or similar fasteners. In one spraying apparatus suitable for use on rockmelons, extensions are used to position the tip of the air funnel 36 30cm from the ground when the rockmelons are small, affording a spray bandwidth of 60cm for rows of melons 2m apart, with the greatest width of the outlet funnel 36 approximately 6-7cm. When no extensions are used, the tip of the air outlet is approximately 115cm from the ground, affording a full spray bandwidth of 2m for the mature crop. If it is desired to spray broader spacing between rows of crops, it is possible to blank off alternate air and spray fluid outlets. Further flexibility for this construction flows from the ease of substitution of various booms with different air outlet spacings, configurations, lengths and diameters. One prototype spraying apparatus of this configuration spans 14m with booms made of 8" steel pipe. This configuration could be used to span from 16m to 20m, and the booms may be tapered toward their extremities to increase the possible span. This configuration allows for a robust, simple and trouble free steel construction, and allows for very high internal air pressures in contrast to the prior art constructions, which are only suitable for low working air pressures. The atomised mist can be projected further, with more penetrating power and directional stability, when higher air pressures can be used. An alternative crop-spraying device in accordance with the present invention is shown in Figures 5 and 7. This configuration allows for broader boom spans through enhanced support of the extended booms. The overall construction of this alternative device is similar to that of the first device described above, essentially with the exception of the boom support means and the hollow joint construction. Fig. 5 shows the rear of the trailer 15 on which is mounted a support structure comprising hollow stems 90 and 91 connected by a bracing member 93 supported by struts 94. Collars 97 are mounted on the stems 90 and 91 so as to turn freely and are fixed at a suitable height to provide appropriate triangulation points for attachment of support lines 98. The support lines 98 run between the collars 97 and the ends of the booms. The lines 98 include turnbuckles 99 to adjust their tension and hence the support they provide for the booms. Although in Fig. 5, the lines 98 are shown attached to lugs at the ends of the booms, the lines 98 may preferably run to supporting points intermediate along the booms, with the tips of the booms being cantilevered from the intermediate supporting points. Fig. 7 shows the detailed construction of the right-hand hollow pivoting joint connecting the air chamber 22 to the booms 14 in this second configuration. The left-hand joint is constructed analogously. A shank 96 fits tightly over the stem 91 so as to turn freely. The boom 14 is connected to the shank 96, defining an opening 101 through the wall of the shank 96. A corresponding aperture 102 is formed in the wall of the stem 91 so as to form a continuous passage between the interior of the stem 91 and the interior of the boom 14 when the boom 14 is set in its extended or desired intermediate positions. The stem 91 may have an annular flange 103 on which rests a corresponding flange 104 on the shank 96. An intermediate layer of fibreglass matting 105 sits between the flanges to facilitate their relative turning. Similar flanges 106 and 107 are provided respectively on the top edge of the shank and the adjacent portion of the stem to prevent the shank rising up on the stem. Instead of support lines 98, each boom 13 and 14 may be supported in this configuration by a cantilevered webbed truss, structurally incorporating the collar 97 and the shank 96. In all other respects, this configuration is similar to the first configuration described. It is to be understood that the foregoing description is put forward by way of example only and the definition of the invention should not be limited thereby.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A crop spraying apparatus comprising: an air impeller; a central air chamber to receive air from the air impeller; a pair of hollow air booms positioned either side of the air chamber and each communicating with the air chamber via a respective hollow joint; a plurality of air outlets along each boom; a spray outlet associated with each air outlet; and means for supplying spray fluid to each spray outlet; whereby air impelled by the impeller into the air chamber passes through the joints, along the booms, and out the air outlets to assist in the delivery of spray fluid from the spray outlets. 2. A crop-spraying apparatus as claimed in claim 1, wherein the hollow joints are adapted to allow the booms to swing between extended positions transverse to, and stored positions parallel to the forward direction of travel of the apparatus, and to allow the booms to be set in intermediate positions between the extended and stored positions. 3. A crop-spraying apparatus as claimed in claim 1 or claim 2, wherein each air outlet is shaped to provide a directed air stream substantially normal to the extended booms, with a downwards and forward component. 4. A crop-spraying apparatus as claimed in claim 3, wherein each air outlet terminates in a flattened conical outlet funnel, and its associated spray nozzle is mounted on a flattened top face of the funnel, so that the spray fluid enters a directed fan-shaped air flow from the above funnel. 5. A crop-spraying apparatus as claimed in claim 4, wherein each air outlet comprises a hollow member between the outlet funnel and the air boom which may be extended in length. 6. A crop-spraying apparatus as claimed in any one of the above claims wherein each hollow joint comprises: a hollow cylindrical stem leading upward from the air chamber with an annular first flange and with a component projecting beyond the flange, and an elbow member leading from a vertical cylindrical section to one of the horizontal air booms, such that the vertical cylindrical section fits over the projecting component and a corresponding flange on the cylindrical section rests on the first flange via an intermediate packing layer. 7. A crop-spraying apparatus as claimed in claim 6, wherein an annular disc positioned on a second intermediate packing layer above the corresponding flange is compressed against the corresponding flange by securing means extending between the first flange and the disc, such that the joint is held together thereby. 8. A crop-spraying apparatus as claimed in any one of claims 1 to 5, wherein each hollow joint comprises: a hollow cylindrical stem leading upward from the air chamber, a hollow cylindrical shank fitting pivotally over the stem, one of the air booms extending horizontally from the shank, and an annular flange on the bottom edge of the shank resting on a corresponding flange on the stem via an intermediate packing layer, the stem having an aperture corresponding with an opening in the shank wall leading into the air boom; whereby air may pass from the air chamber through the aperture and into the air boom when the boom is set in an extended or intermediate position. 9. A crop-spraying apparatus as claimed in claim 8, wherein a circular collar is pivotally fitted on a portion of the stem above the shank and is fitted with a support line leading to a support point along the boom, and wherein a bracing member extends from the stem to the corresponding stem associated with the other joint. 10. A crop-spraying apparatus as claimed in any one of the above claims, wherein each air boom is swung on its respective joint by means of a double acting hydraulic ram pivotally joined to the air chamber and a projection from the upper part of said respective joint.

Inventors: SARTOR GIUSEPPE MARIO, SARTOR, GIUSEPPE, MARIO
Applicants: SARTOR GIUSEPPE MARIO, SARTOR, GIUSEPPE, MARIO
Application year: 1987
Main classification: B05B1
IPC codes: A01M7, B05B7