AN APPARATUS WITH AT LEAST ONE LIQUID NOZZLE FOR SPRAYING LIQUID ON PLANTED FIELDS

Abstract: In an apparatus with at least one liquid nozzle (2) for spraying liquid on planted fields the novel feature is that each liquid nozzle (2) is surrounded by an air nozzle (2) ejecting a hollow cone-shaped air jet. Hereby is achieved that the liquid fog ejected from each liquid nozzle (2) is kept within a desired, restricted area, as the hollow cone-shaped air jet acts like a casing protecting the liquid fog against the wind. Besides, by a suitable balancing of the supply of liquid and the supply of air it is possible to achieve the formation on the inside of the hollow cone-shaped air jet whirls partly flowing backwards, which bring the liquid fog into contact with the ventral sides of the leaves of the plants.

Description: An apparatus with at least one liquid nozzle for spraying liquid on planted fields. TECHNICAL FIELD The present invention relates to an apparatus for spraying liquid on planted fields, said apparatus being of the kind set forth in more detail in the preamble of claim 1. BACKGROUND ART Prior apparatus of this kind have various disadvan- tages, of which the two most important ones are that the liquid drops ejected are easily influenced by the wind and therefore do not reach their disti- nation, and that the sprinkling becomes irregular, partly be- cause the lower leaves are "shaded" by the upper leaves, partly because very often the ventral sides of the leaves do not receive any liquid at all. DISCLOSURE OF THE INVENTION The object of the present invention is to provide the construction of an apparatus of the kind referred to above, which does not have the above-mentioned disad¬ vantages, and said object is achieved by an apparatus, which according to the invention shows the features described in the characterizing clause of claim 1. Hereby is achieved partly that the liquid drops eject¬ ed from the liquid nozzle are caught and directed by the air jet, whereby the wind influence is considerab¬ ly reduced, partly that the air jet makes the plants and their individual parts move with the effect that the liquid is spread considerably more regularly on all surfaces of the plant, including the ventral sides of the leaves, which receive liquid from air jets with partly upwards directed courses produced in the inte- rior of the hollow cone-shaped air jet. Preferred embodiments of the apparatus according to the invention are described in claims 2 to 8, and the effects of said embodiments are explained in more detail in the following detailed part of the present specification. BRIEF DESCRIPTION OF THE DRAWING The invention will be described in more detail below with reference to the embodiment of a nozzle unit shown in the drawing, said nozzle unit together with a number of other nozzle units of the same kind forming part of an apparatus (not shown) for spraying liquid. DESCRIPTION OF THE PREFERRED EMBODIMENT Similar to prior apparatus of this kind the apparatus according to the invention comprises a container (not shown) for the liquid to be ejected as well as a so- called spray bar (likewise not shown) carrying a num¬ ber of downwards directed nozzles, through which the liquid is sprayed over a planted field in a manner known in principle. Said equipment, which may in addi- tion comprise the required pumps, filters etc., is usually adapted to be carried by a tractor and driven by the power-drive attachment thereof. As the invention only deals with the aforesaid nozzles and the elements closest related thereto, only a single nozzle unit 1 is shown in the drawing,which nozzle unit will be described in more detail below. The nozzle unit 1 comprises a liquid nozzle 2, which together with a swivel 3 situated upstream is secured and connected to a liquid supply tube 4 by means of a coupling nut 5 countersunk in a recess 6 in the nozzle unit 1. In the exemplary embodiment shown the liquid nozzle 2 is of the kind, which in cooperation with the swivel 3 ejects the liquid supplied under pressure through the liquid supply tube 4 as small drops in a flow, which has the shape of a hollow cone with an appreciable angular extension 7 from the axis 8 of the liquid nozzle 2. However, the desired effect may be achieved by means of liquid nozzles, which produce other ejec¬ tion patterns, e.g. the so-called flat nozzles, which eject the drops in a fan-shaped pattern. The most important feature in the present connection is that the angular extension 7 of the ejected "fog jet" is not inconsiderable and the effect hereof will be ex¬ plained below. For the sake of good order it should be noted that in the present specification the term "fog" should be understood as comprising a large number of small li¬ quid drops, the size of which is not limited to the size of the drops forming natural fog. The liquid nozzle 2 is coaxially surrounded by an air nozzle 9 with an annular nozzle opening, which consti- tutes the mouth of a sectionally annular duct diverg¬ ing in the flow direction, which duct is limited on the outside by a conically diverging wall 11 and on the inside by a conically converging wall 12. Air is supplied to the air nozzle 9 from means (not shown), e.g. an air tank common to various nozzle units, through an air supply duct 13, the downstream end of which is limited by an exterior wall 14 and a conical- ly diverging interior wall 15, in such a manner that the downstream end of said air supply duct 13 in cooperation with the space between the aforesaid di¬ verging and convering walls 11 and 12, respectively, constitutes a converging-diverging duct 16. As will appear from the drawing, the converging-diverging duct 16 does not contain any sudden shifts in the flow cross-section and thus only causes small losses in effect. Inside the nozzle opening 10 is situated a number of mainly radial guide plates 17, which may be brought into various angles with meridian planes by means of a rotatable adjustment ring 18 so that said guide plates 17 signal a larger or smaller velocity component in the tangential direction to the air flowing out at a great velocity, whereby the air flow shaped as a hollow cone will rotate more or less as indicated by the arrows 19. As the flow of small drops leaving the liquid nozzle 2 will be caught by the air flow from the air nozzle 9 somewhere below the nozzle unit 1, it will primarily be said air flow that determines the further passage of the drops, as the mass of the individual drops is so insignificant that their kinetic energy is not sufficent to resist the influence from the air flow. Besides, this corresponds to the disadvantageous ex¬ perience found in prior apparatus of this kind, in which the liquid nozzles are not surrounded by air nozzles, and thus the ejected jets are easily carried away by the wind. Obviously, the strong, sectionally annular air flow from the air nozzle 9 is bound to carry away the air closest to the jet. Hereby a vacuum is produced inside the air jet in the area about the liquid nozzle 2, and it has been found that said vacuum causes some return flow from the hollow cone-shaped air flow as indicated by arrows 20. It has also been found that the air so flowing back carries away liquid drops and deposits them on the ventral sides of the leaves of the plants growing on the filed in question. Simultaneously, the rotation of the air produced by the guide plates 17 causes the plants to be bent in a most gentle manner and possibly turned a little, which furthermore en- sures that also the upper side of leaves "shaded" by higher leaves as well as the stems of the plants are equally covered by exactly the liquid quantity re¬ quired for the actual purpose. By adjusting the pressure, at which the air is supplied through the air supply duct 13, and by adjusting the guide plates 17, it is possible to adapt the process to various types of plants. Thus, in case of sprinkling of e.g. mechanically weak plants, it will be appropriate to use a relatively low air velo- city and a correspondingly low rotation of the air jet. Obviously, the ejection of liquid through the liquid nozzle 2 may be changed in a manner likewise known by changing the liquid nozzle 2 itself and/or the swivel 3, as said parts may easily be changed by removing the coupling nut 5 and reinserting it after the insertion of other parts with different characte¬ ristics. As shown in the drawing it is appropriate that the innermost limitation of the nozzle outlets 10 lies at a not inconsiderable distance from the liquid nozzle 2, as this permits the constitution of a space inside the hollow cone-shaped air flow, in which as mentioned above a vacuum is produced, which causes the aforesaid return flow, cf. the arrows 20. For the sake of good order it should be noted that the manner, in which the guide plates 17 are adjustably situated, is shown only very schematically, as anyone skilled in the art would know how to construct the means required therefor. The entire nozzle unit 1 may - possibly together with several similar nozzle units - be adapted to be angu¬ larly adjusted in various directions.

Claims: CLAIMS 1. An apparatus for spraying liquid on planted fields and of the kind comprising at least one liquid nozzle (2), from which liquid supplied under pressure is ejected in the form of a fog of small drops, c h a¬ r a c t e r i z e d in a) that each liquid nozzle (2) is of the kind adapted to eject the liquid in the form of a fog jet having in at least one direction at right angles to the axis (8) of ejection of the nozzle (2) a not inconsiderable angular extension (7) relative to said axis (8), and b) that at a not inconsiderable radial distance each liquid nozzle is mainly coaxially surrounded by an air nozzle (9) provided with a mainly annular nozzle outlet (10), which air nozzle (9) is adapt¬ ed to supply an air flow shaped like a truncated hollow cone, the exterior side of which diverges in the flow direction. 2. An apparatus according to claim 1, c h a r a c¬ t e r i z e d in that each air nozzle (9) is adapted in such a manner that the interior side of said hollow cone converges in the flow direction. 3. An apparatus according to claim 1 or 2, c h a- r a c t e r i z e d in that each air nozzle (9) is provided with adjustable guide plates (17), by means of which a component of motion in the tangential direction may be signalled to the air flowing from the air nozzle. 4. An apparatus according to one or more of the claims 1 to 3, c h a r a c t e r i z e d in that each liquid nozzle (2) is of the kind producing a hollow cone-shaped fog jet. 5. An apparatus according to claim 4, c h a r a c¬ t e r i z e d in that the liquid nozzle (2) is provi¬ ded with means, e.g. a swivel (3), by means of which a component of motion in the tangential direction may be signalled to the liquid flowing through the liquid nozzle. 6. An apparatus according to one or more of the claims 1 to 5, c h a r a c t e r i z e d in that the sectionally annular nozzle outlet (10) of each air nozzle (9) is limited outwardly by a wall (11) mainly conically diverging in the flow direction and inwardly by a wall (12) mainly conically converging in the flow direction. 7. An apparatus according to claim 6, c h a r a c¬ t e r i z e d in a) that said conically diverging wall (11) consti¬ tutes a continuation of the exterior wall (14) in an air supply duct (13), through which air may be supplied to the air nozzle (9), and b) that said conically converging wall (12) consti¬ tutes a continuation of a diverging interior wall (15) in the flow direction in said air supply duct (13), all in such a manner that upstream to the nozzle outlet (10) of the air nozzle (9) a converging-diverg¬ ing sectionally annular duct (16) is formed, which is mainly free from sudden shifts in the flow area. 8. An apparatus according to one or more of the claims 1 to 7, c h a r a c t e r i z e d in that each liquid nozzle (2) and the corresponding swivel (3) are secured to the liquid supply tube (4) by means of one and the same coupling nut (5) mounted in a recess (6) situated inside the nozzle outlet (10) of the air nozzle (9).

Inventors: ROSENBAEK DAN, ROSENBAEK, DAN
Applicants: DEMS ENG, DEMS ENGINEERING I/S
Application year: 1989
Main classification: A01M7
IPC codes: B05B7