Process and device for the mechanical spraying of liquids

DESCRIPTION OF THE INVENTION

The invention concerns a process for the mechanical spraying of liquids, preferably with aerosol formation, as well as a device required for carrying out this process.

The word “liquid” as used in this invention means solutions and emulsions as well as suspension, “aerosol” means primarily mists which are produced by atomizing solutions or emulsions in the air.

Usually, spraying liquors for the production of aerosols are sprayed from nozzles, e.g. of the venturi type. It has also been suggested to produce aerosols by spraying the liquid to be sprayed, from a nozzle onto one side of a flat wall terminating an air pipe, while the air stream coming out of the pipe escapes through a vent which forms a U- or horseshoe-shaped terminal edge with the wall and thus the liquid film flowing down over the wall is broken off and atomized. The flat surface of the wall together with the shape of the vent thus formed, however, cause the liquid to be sprayed in a cloud whose drift is completely dependent upon the prevailing direction of the wind. Especially with a strong side wind, an undesirable drift of the spray cloud in a sideward direction results. A further consequence is that, e.g., when such a spraying device is used for the treatment of agricultural cultivations, it is impossible to attain a uniform, even spraying of the plantation to be treated.

It is an object of the invention, therefore, to avoid the said deficiencies by providing a device and a process for the production of a substantially vertically downward directed spray cone which is as uniform as possible.

In this manner, an atomization of the liquid, e.g. a spraying liquor, is attained by the novel process which is at least as fine as that attained by known devices. In addition, it is possible with the new device, in contrast to the last-described known device, to direct the atomized cone substantially vertically or as desired, at a slight angle to the vertical towards a surface to be sprayed, e.g. a planted field. Due to the special form of the spraying device it is possible, by means of the spray cone which is directed substantially perpendicular to the field, to appreciably prevent a drifting of the sprayed material, even with a strong side wind. Thus an even spraying of each portion of the area to be treated is assured, and the disadvantages of an uneven distribution of the sprayed liquid droplets over the treated area are substantially avoided.

As a result of this even application of the liquid to be sprayed onto a surface to be treated, the consumption of the liquid, in spite of maximum effectiveness, its less than that required in most of the known devices.

The process according to the invention comprises the mechanical formation of aerosols, preferably for the treatment of agricultural plantations, and comprises producing a downwardly flowing liquid film on a slanted surface of ringshaped, downwardly widening cross section, and breaking up said film at an annular interrupting edge of said surface which edge is substantially horizontally situated, by an air stream which is escaping under slight excess pressure from the interior of the at least approximately cone-shaped hollow space formed by the liquid film, whereby the latter is atomized, while forming an essentially vertical, downwardly directed spray cone.

The liquid film can be of annular, elliptical or similar ringshaped, e.g. an elongated ring-shaped or “race-track” C~~) cross section. Especially when the process according to the invention is employed for the treatment of agricultural plantations, it is not necessary to raise the temperature of the escaping air stream above that prevailing in the surrounding area or to employ an air pressure of more than 1 atmosphere excess pressure. For agricultural application, an air stream is preferably employed which has a pressure of at least 0.1, preferably however about 0.4 atmosphere of excess pressure, when entering the above- described space surrounded by the liquid film; depending on the purpose of application, higher pressures, e.g. 1.5 to 2 atmospheres above the ambient pressure, can be used.

A particular feature of a preferred embodiment of the process according to the invention comprise so directing the air stream in the interior of the said hollow space that it forms a mantle of correspondingly shaped cross section, e.g. instead of a solid cone, a cone mantle of variable thickness, in the side and upper portion of the said hollow space.

By increasing or decreasing the thickness of this mantle formed by the air stream, the exit velocity of the air stream can be varied so that the particle size of the liquid to be sprayed as well as the degree to which the resulting spray cone is filled with the mist formed can be adjusted as desired.

The device according to the invention for the application of the above-described process has an air supply line having a downwardly widening mouthpiece pointing downwards and preferably of ring-shaped, or of elliptical, or of elongated ringshaped cross section, as well as a liquid supply line having one or a plurality of downwardly directed outlet orifices, which liquid supply line is mounted on the outer wall of the mouthpiece encircling the latter in a substantially horizontal plane. Thus the liquid, e.g. a spray liquor, flowing downward on the outer wall of the mouthpiece below the said outlet orifice or orifices contacts the air stream escaping from the mouthpiece at the lower terminal edge thereof and is atomized thereby in the form of droplets in a spray cone having the main axis thereof directed substantially vertically downward.

According to another feature of a preferred embodiment of the device according to the invention, a crown like ridge of teeth or the like projections is mounted on the outer wall of the mouthpiece between, on the one hand, the plane in which the said outlet orifices are located and, on the other hand, the lower terminal edge of the mouthpiece in an intermediary plane extending parallel to the terminal edge, said ridge preferably extending in the direction of the intermediary plane. This contributes considerably to an even distribution of the liquid film in the lowest zone of the outer wall of the mouthpiece down to the terminal edge thereof.

The above-mentioned preferred embodiment of the process according to the invention is attained, e.g., by mounting a limiting body which conforms in shape to the said mouthpiece, inserted into the mouthpiece from below and preferably arranged coaxially with the latter, the outer wall of which limiting body preferably extends parallel to the inner wall of the mouthpiece; the interval between the limiting body and the inner wall of the mouthpiece can be adjusted by raising or lowering the limiting body along the common axis.

By this means the shape and the general direction of the spray cone, and also the size and distribution of the liquid droplets in the mist formed are regulated.

In an especially preferred embodiment of the device according to the invention, the liquid supply line mounted around the mouthpiece is provided at its lowest point, preferably directly above the part of the outer wall of the mouthpiece next adjoining the supply line downstream, with a continuous outlet aperture having an adjustable cross section. In this manner the optimal amount of liquid to be sprayed for a given air stream can be set and optionally varied. The same purpose can be achieved by mounting a valve regulator, not shown in the drawings, in the inlet pipe to the liquid supply line.

In this arrangement, it is also preferred to provide the above-mentioned ridge of teeth or the like below the outlet aperture for improved distribution of the liquid.

In a preferred application of the apparatus according to the invention, an excess pressure of 0.4 atmospheres and a compressed-air consumption of about 1,000 m³per hour is used, and a device according to the invention is employed which preferably has a mouthpiece with an aperture angle of about

90° and the limiting piece which extends into the mouthpiece has an aperture angle of about 120°—140°, while the height of

3,608,822 the mouthpiece (height of the cone frustum) is about 40—50 mm. The device is preferably so adjusted that the interval between the lower edge of the mouthpiece and the other wall of the limiting piece is such that the latter protrudes somewhat beyond the outer edge of the mouthpiece.

By means of this latter measure, a maximal interaction of the air escaping from the mouthpiece with the liquid film along the terminal edge is achieved, and thus the finest atomization and greatest diameter possible in the spray cone at a given aperture angle of the mouthpiece is assured. In the accompanying drawings the device according to the invention is illustrated by a number of nonlimitative embodiments of the invention, which device enables the most practical performance of the process according to the invention.

In the drawings:

FIG. 1 illustrates, in perspective view a preferred embodiment of the spraying device according to the invention.

FIG. 2 shows a vertical section through the embodiment shown in FIG. 1, in the plane passing through the line II—II. FIG. 3 illustrates a modified embodiment of the liquid supply shown in FIGS. 1 and 2. FIGS 4α, 4b and 4c shown three different embodiments of the device according to the invention as seen from below. FIG. 5 shows, only schematically, a preferred construction of the mouthpiece and the limiting piece. Finally, FIG. 6 shows the assembly of a plurality of devices according to the invention in an aggregate for the operation of the same, such as can be mounted, e.g., on a tractor.

In particular, the embodiment of the device according to the invention shown in FIGS. 1 and 2 and 4α consists of a cone-shaped outer mantle 1 which is open at its wider lower end and forms a circular atomizing edge la,while at its narrower upper end,' it opens into a feed pipe 2 which in turn is connected to a compressed-air pipe 3.

In the interior of the feed pipe 2 an adjustable device 5 is mounted in a suitable manner, e.g. by a stationary pin 4 which is embedded at both ends in the wall of the feed pipe 2, which device comprises the cone frustum mantle 6 with closed top, the bolt 7 provided with an exterior thread, and a support 8 for the bolt 7, said support 8 being preferably in the form of a screwed nut and being provided provided with an interior thread and mounted stationarily on the cross pin 4. Stop heads 7α and 76 limit the distance of adjustment. Bolt 7 can be provided at its lower end with a control handle which is not shown. By adjusting the bolt 7 in the support 8, the inner cone frustum 6 can now be raised or lowered in respect to the outer mantle 1 so that the cross-sectional area of the cone mantleshaped air channel formed between the mantles 1 and 6 is increased or decreased. Thus the velocity of the airstream flowing out of the compressed-air pipe 3 via the feed pipe 2 through the said channel in the direction of the arrow is decreased or increased, and depending on the distance and the relatively higher or lower position of the lower edge 6α or 6α' of the inner cone mantle 6 in respect to the front edge la of the outer cone mantle 1, the density and the mean downward direction of the airstream when leaving the said channel are also varied.

The liquid to be sprayed, e.g. a spraying liquor for agricultural purposes, is supplied to the outer wall of the cone 1 out of a main supply pipe 9 via one or a plurality of branch pipes 10 and a ring-shaped distributing pipe 11, which is endless or optionally divided into segments, and provided on the lower side thereof with orifices 12. In order to better combine the liquid streams leaving the orifices 12 into a single film, preferably a crownlike ridge 13 is provided, having teeth 14 or similar projections, which ridge extends substantially horizontally and is fastened on the outer annular mantle 1 below the distributing pipe 11.

The liquid film flowing over the outer wall of the cone mantle 1 below the ridge 13 is caught up at the terminal edge la of said mantle 1 by the airstream escaping from the above-mentioned channel and carried along in smaller or larger droplets, thus forming an annular spray cone which is approximately defined outwardly by the extension of the wall of the cone 1, and inwardly, both in density and in the mean direction of flow, by the position of the terminal rim 6α of the inner cone 6 in relation to edge la.

In contrast to the known spraying device described in detail above, the spray cone formed below the edge la is much less sensitive to a side wind, a fact which is largely due to the outer cone mantle 1 protecting the air cone which forms, so that there is no appreciable drift of the sprayed material.

The modified embodiment of the liquid supply shown in FIG. 3 consists of a flange 15 located at the end of the supply pipe 10, which flange is screwed by means of threads and, preferably, intermediary sealing gasket 16, onto the inlet pipe 17 of a collecting chamber 20 extending annularly in a horizontal plane around the outer mantle 1. Whereas the upper end wall 21 bearing the inlet pipe 17 is joined stationarily to the mantle 1 at position 22, the lower end wall 23, which in the embodiment of FIGS. 1 and 2 has the form of a cylindrical mantle, can be adjusted in height relative to the lower end of the upper end wall 21 by suitable means, e.g. adjusting screws 24, and thus the distance of the lower edge of the front wall 23 from the outer surface of the cone mantle 1, i.e. the continuous outlet aperture 12α, can be increased or decreased. In this manner the thickness of the liquid film flowing out at the lower end through this aperture 12α of the chamber 20 can be varied. The mounting of a crownlike ridge 13 can optionally be omitted.

Whereas FIG. 4 a shows the view from below of the embodiment according to the invention shown in FIGS. 1 and 2, the FIG. 46 and 4c show modified embodiments in which the cone mantles 1 and 6 are replaced by elongated mantles 25 and 26 having an elliptical cross section (FIG. 46 or having an elongated ring-shaped cross section, i.e. a( ) -shaped cross section, as in the case of the mantles 27 and 28 in FIG. 4c,

FIG. 5 shows purely schematically a preferred construction ofthe mouthpiece 1, which in this case has an aperture angle of 90°, and ofthe limiting piece 6, which has an aperture angle of 130° in the embodiment shown. The same elements shown in FIG. 1 are used to adjust the interval between the two parts; the provision for liquid and air is also the same as shown in FIG. 1.

Finally, FIG. 6 shows an aggregate comprising compressedair supply pipes 30 and 31 each bearing three spraying devices 33 according to the invention directed downwardly and supplied, via the distributor 35, with compressed air from an air compressor 34, shown only schematically, the air preferably having less than 1 atmosphere excess pressure. To each of the air supply pipes 30 and 31, a liquid supply pipe 36, 37 is connected, which is fed from a reservoir 39 via a pipe 40 by means of a pump 38. Both the compressor 34 and the liquid supply pump 38 are driven by suitable transmission means 41,42, e.g. transmission gears, from a driving shaft 43, which is driven directly by a separate motor or also by the motor which drives the agricultural tractor bearing the entire aggregate, via a universal joint, not shown.

In the embodiment of FIGS 1 and 2, the cone mantle 1 and the cone mantle 6 both have an inclination of about 60° relative to the essentially vertical main axis of the cone. By constructing this cone with a wider or narrower angle, the width of the area to be sprayed can be varied and when the supply of liquid and air remain constant, the droplet formation in the resulting mist can also be varied. Whereas the above detailed description of the mode of performing the invention is primarily employed for the formation of aerosols having little drift when influenced by a side wind, which occurs in the treatment of agricultural plantations, the process and device according to the invention can, of course, also be employed for spraying purposes of of a nonagricultural nature, e.g. for spraying used to regulate the moisture in air-conditioned rooms or for hygienic purposes, or also for finely dispersing a liquid in chemical reaction chambers and the like. The easy accessibility and simplicity of the construction of all of the individual parts of the spraying device according to the inven

3,608,822 tion and, in particular in the embodiment supplying the liquid as shown in FIG. 3, as well as very low sensitivity of the liquid outlet on the outer wall of the cone mantle 1 to clogging are particularly advantageous.

As an alternative, two liquid supply pipes can be provided instead of the single pipe 9 in FIG. 1 as well as corresponding separate intermediate pipes 10, which lead to two separate semicircular distributing pipes 11, and two separating strips, not shown in FIG. 1, can be provided to extend axially on the cone wall down to the discharge edge la on each of opposite sides of the cone mantle 1 between the semicircular distributing pipes 11. In this way it is possible to simultaneously spray two different liquids which do not come into contact with each other on the surface of the cone mantle, but only in the spray cone forming below the device according to the invention, and which optionally may be capable of reacting chemically with each other.