JPH0380067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of small particles of charged material and to the use of such small particles. This material contains pesticides, herbicides,
It may be an agricultural chemical such as a fungicide or a fertilizer for growing plants or seeds, the particles being electrostatically charged droplets with diameters on the order of a few micrometers to 100 micrometers or more. could be. This material is usually dissolved or dispersed in a liquid.

Existing or proposed safety and economic requirements for the use of agricultural chemicals mean that the spraying of these chemicals must be more precise to achieve the expected desired results. are doing.

It is an object of the present invention to provide a better spray head device and method of atomizing charged spray using such a head.

The present invention provides a spray head for a spray nozzle that includes a hood defining a surface extending forward from the nozzle. This hood also supports an insulating frame of an electrode device that can be excited to generate a charged field in front of the nozzle during operation that exerts an induced charging effect on the liquid sprayed from the nozzle, and further supports charged and uncharged Preventing liquid spray from returning to the electrode device and its mounting member or frame.

If the liquid to be sprayed is non-conductive, the hood may be constructed of a conductive material or provided with a conductive surface. The nozzle or support can be grounded via the conductive liquid being sprayed, or separately if the liquid is not conductive.

The insulating electrode frame may be convoluted to prevent formation of a liquid path from the electrode to ground.

The spray head may be configured to be easily attached to and detached from the spray nozzle or its support lance.

The spray head may have means for retaining and collecting spray that rebounds onto the head without allowing it to fall.

Such a spray head provides better atomization with less chemicals and diluent, and provides more predictable application rates.

The electrode device may consist of a plurality of electrodes facing each other in front of the nozzle.

This electrode device can be selected to change the shape of the spray fanned out from the nozzle.

According to one particular aspect of the invention, a spray head as described above is provided with at least one elongated projection and means for controlling the flow of liquid, said means directing the liquid on the spray head towards said projection. and flows along it so that, in cooperation with the electric field at the level of the spray head, the liquid falls from the projection in the form of droplets.

The protrusion may form part of the hood. The protrusion may also be attached to or part of the electrode frame. These protrusions may be integrally formed on the hood or electrode frame or may be additionally attached. Each of the protrusions or protrusions may have one or more sharp edges.

When using a conductive liquid, the protrusion may be formed of an insulating material.

The hood may have one or more protrusions. The hood protrusion or protrusions may be provided to extend in the direction of the trajectory of the liquid sprayed from the nozzle to approach the space charge region.

The present invention will be explained in more detail below by giving non-limiting specific examples based on the accompanying drawings.

FIG. 1a shows a spray head 20 which is attached to a spray lance 10 having a spray nozzle 11 at its tip. The head 20 may advantageously be attached by a nut and a thread on the tip of the spray lance, but if desired it may be attached by a push-on or clip-on type well known to those skilled in the art. It may have the structure of an expression. Spray lances may be of the type readily available for use in agriculture and horticulture.

Spray head 20 includes a generally box-shaped hood 30 formed of a material to be described below. As shown in the picture, only three sides of this box are used;
The front and bottom surfaces are open. The top surface 36 has approx.
A fourth surface 35 is provided with an inclination of 45 degrees.
Side surfaces 32 and 33 are configured to support electrode frames 41, 42 of the electrode device. The electrode device consists of a plurality of mutually opposite electrodes,
One of them is designated 43 in FIG. 1 (the other electrode 48 is on the frame 41 and is not visible in FIG. 1). These electrode frames are fixed to the hood 30 through mounting holes such as 34 with nuts 50, for example. Conductive wires such as 44 apply electrostatic voltages to electrodes such as 43 and 48. Advantageously, the electrode 48 is constituted by a metal plate carried on the head 47, and the contact wire 44 is passed through the stem 49 to effect contact. Electrode and connecting wire 44
The connection to the other end may be implemented in various ways depending on the particular application and is therefore not shown in detail here.

Frames 41 and 42 are generally pulp-shaped and made of an insulating material, such as a plastic material. FIG. 1b shows the electrode 41 in cross section. The junction of stem 45 and head 47 is truncated at 46 to increase the leakage path from the electrode to the hood and to facilitate the delivery of liquid which may increase the conductivity of this path. Advantageously, the frame is divided into two parts: a head 47 and a stem 49. The stem may also have a recess to facilitate liquid delivery.
Other electrode devices may be used depending on the particular application if deemed more appropriate. The number and shape of the electrodes can be varied, for example, to match the shape of the spray.

Hood 30 is formed of any suitable material, such as metal or plastic. If non-conductive liquids are to be sprayed, the hood must be made conductive or provided with conductive surfaces, preferably on the inside and outside. The hood may be constructed of an insulating material if the liquid is sufficiently conductive.

Advantageously, a trough or other collector 31 is provided around the open edges of the hood, both inside and out, to collect and transfer liquid deposited on the hood to a larger collector (not shown), as described below. Dispose of or reuse. Appropriate equipment may use suction to facilitate this liquid collection. Absorbent materials may be used if appropriate.

Spray nozzle 11 has any suitable shape to obtain the desired spray pattern and droplet size. Lance 10 and Lance 1
0, care must be taken to provide a conductive path so that the hood 30 is grounded or at least earthy, as shown by ground connection 21 in Figure 1a. There is. This does not necessarily mean that you should actually use a ground wire. This is because if the liquid to be sprayed has sufficient conductivity, the lance 10
There is no need for any other grounding arrangement other than at the level of the liquid source (not shown) at the far end of the hood. If the liquid is not sufficiently conductive, it must be properly grounded, for example via a conductive lance 10 or an auxiliary conductor. If necessary, the wire may be run to the ground to provide proper grounding.

The operation of the spray head of the present invention is as follows. The electrodes are first energized by a suitable high voltage source.
For a typical small atomizer of the "knapsack" type, the hood is a few square centimeters (up to 10 cm across in metric terms) and a voltage of about 3 KV with a current drain of a few microamps is appropriate. In this embodiment, the electrodes are both connected to a common pole of the supply, the other supply pole being grounded or at ground.

A spray emitted from a nozzle 11 receiving pressurized liquid in a known manner passes between the electrodes, so that the liquid droplets of the spray are electrically charged. The spray is charged by induction to the opposite polarity of the voltage applied to the electrodes. Space charges are also generated in a known manner. Without the spray head hood, some of the spray droplets would bounce off the electrode frame, creating a conductive path that shorted out the electrostatic supply. Grounded inner and outer surfaces of the hood;
In particular, the outer surfaces (which have a grounded state or are grounded by a conductive liquid coating) trap droplets bouncing off the spray in cooperation with the space charge, so that the liquid is deposited on the electrode frame. This avoids or at least reduces the accumulation of The spray captured in liquid form on the hood may be allowed to fall directly into droplets, but is preferably collected and stored, for example in a trough 31. Absorbent materials such as wicks may be used if appropriate.

As previously described, measurements of the effectiveness of spray head configurations using multiple opposite electrodes in the nozzle hood have shown that for a given application rate of diluted chemicals, a smaller amount of active ingredient can be obtained for a given application rate of the diluted chemicals. It has been found that this can also be achieved with chemicals and diluents and with high power, ie, by increasing the ground speed of the sprayer.

A suitable high voltage power unit is shown in FIG. This unit is energized by a battery B, which advantageously consists of three 9VPP9 stacked dry cells. Semiconductor dc/dc converter HVC
provides direct current at a nominal voltage of 3KV for a 12V input. The supply to the converter HVC is via a regulator REG which provides a stable 12 volt voltage from the batteries as their voltage decreases with use. When the battery life ends, an alarm AL activated by voltage comparator VC sends a signal. Comparator VC is a differential amplifier with one input supplied by the reference Zener diode Z and one input supplied by the battery voltage via a voltage divider. A suitable alarm level is 14V.

Some power is lost in the regulator REG, but this is unavoidable in order to stabilize the spray conditions and thus distribute the material consistently. More effective but more complex techniques may also be used, such as those based on the "Chopper" regulator. The converter HVC in this embodiment is of type 12GM3000P manufactured by Alpha Repeater Ltd.

Figure 3 shows the results of testing sprays used to treat potato seedlings at recommended application rates and dilution rates. The chemicals to be sprayed are represented by UV sensitive dyes known to those skilled in the art. The recommended application rate is equal to 1000 diluents per hectare. Samples of potato seedlings were lined up in a row, and spraying was carried out by moving the spray head parallel to the row of seedlings on a conveyor. Moves at 0.25m/sec 790
A spray nozzle was used that produced atomization at a rate of ml/min. In this way, the desired application rate can be obtained when a plurality of rows of seedlings are arranged at intervals of 0.5 m from each other and each row is sprayed alternately. (The spray pressure is determined by Spraying System Co., Ltd.)
Systems Ltd.) TEEJET (RTM) type
It was 3 bar with an 8002 nozzle. ) No charge was applied to this test as it was a test for normally recommended usage.

The graph in FIG. 3 shows the probability Ps (%) of a site, such as a leaf or stem of a seedling, to which a certain amount of the chemical adheres. The amount of chemical deposited is shown in microliters (μ) per cm ² of leaf or stem on the Y axis, and the probability of site is shown in % on the X axis. This graph shows that on average 50% to 80% of the sites have a minimum amount of drug attached. That is, according to the above-mentioned recommended spraying method, 0.4 to 1 ^cm2 of drug
A chemical of 0.2μ is attached (in both cases, both the front and back sides are measured). Therefore, if applied at a rate of 1.5 kg of chemical to 1000 diluent per hectare, per 1μ
The chemical will adhere at a rate of 1.5 μg, or 0.6 to 0.3 μg per cm ² of leaf or stem.

FIG. 4 shows the results of two tests conducted using the spray head of the present invention with a hood attached. TEEJET Spray Nozzle (RTM)
It was changed to type 800067 and tested again using a pressure of 3 bar and a flow rate of 250 ml/min. The nozzle is
It was moved at 0.87m/sec. When testing with these species changes, the required application rate is reduced by a factor of 10, to just 100 per hectare. In FIG. 4, curve E represents the amount of deposit when charged by excitation of the electrode, and curve O represents the amount of adhesion when sprayed without excitation of the electrode, and therefore when the droplets are uncharged. There is. As is clear from this graph, an amount of chemicals exceeding 0.19 μ/cm ² adheres to 50% of the area. To obtain the aforementioned 0.6 μg level of drug, only 0.32 Kg of drug per 100 diluent needs to be used. Of course, some savings can be made if the spray is not so sprayed that it "runs away," but in that case, as curve O shows, the chemical concentration must be more than doubled.
In other words, the desired amount of adhesion cannot be obtained unless the amount is about 0.8 kg/100. This results in a higher concentration of chemical in each deposit, again resulting in considerable waste of chemical and a more "crusty" application.

Thus, the overall result of electrostatic spraying using a hooded, inductively charged spray head is to use 1/5th the chemicals, 1/10th the diluent, and 3x the power (0.20 to 0.87 m/s). seconds) to achieve the desired chemical deposition rate.

The overall improvement will of course depend on the nature of the spray coverage. For immobile pests and contact-acting insecticides, a deposition rate of 80% is probably preferable to 50%. In this case, a charged spray is much better than an uncharged spray.

The use of smaller inductively charged droplets has the additional advantage that when the spray is fanned onto a vertical surface, the electric field from the charging electrode expands the fan spray horizontally by electrostatic action. This results in better results overall. Overall, more material is deposited with less total consumption and the coverage is improved due to the smaller drops.

The spray is applied to the hood surface 3 set on the lance by an operator who moves while walking along the rows of seedlings.
It has been found to be advantageous to spray perpendicular to the row from a height of about 45°, with the column 6 maintained approximately horizontal.
However, the hood surface 36 may be inclined up to 30 degrees about the axis of the lance as long as the electrodes are not wetted by the spray. Use a 100 mesh filter for the 800067 nozzle.

Another embodiment of the spray head of the present invention is shown in FIGS. 5 and 6. This spray head 120 has a generally similar construction to the previously described spray head and may be mounted on the spray lance 110 or for other applications related to hydraulic noise, such as on a playboom equipped with such a nozzle. It has a hood-shaped member 130 that is used for purposes such as mounting.

The hood 130 of FIG. 5 is generally U-shaped and constructed of conductive metal or plastic material. If a plastic material is used, a conductive metal coating may be required unless the liquid to be atomized is sufficiently conductive. hood 130
The surface area of the hood is smaller than that of the hood in FIG. This reduced surface area also reduces the amount of liquid that can be collected. As clearly shown in FIG. 6, the hood is larger than the electrode frames 141, 142. This has been found to be a desirable structure in maintaining an effective barrier against spray liquid splash. Electrode frames 141 and 142 are similar to the frames of FIG. 1 and are secured to hood sides 132 and 133 via nuts and flanges such as 150 and 149. EHT supply lead 144 extends to electrode 148. Hood 130 is 148
lance 110 such that the spray 160 of liquid from nozzle 111 is charged during operation by the electric field from these electrodes to ground when electrodes such as
and the spray nozzle 111. The local source pole is then connected directly or indirectly to the nozzle 111 and is usually grounded for safety and convenience. Spray 160 is ejected in this embodiment into a fan shape defined by nozzle 111 on the plane of FIG. 6, but may be deformed by electrolysis if desired.

Hood 13 as shown in these drawings
0 and the electrode frames 141 and 142 are provided with protrusions. These protrusions consist of elongated members with sharp edges, the presence of which provides the important advantage that the liquid flows along these members to said sharp edges, where it breaks down into droplets under the action of an electric field. The protruding parts of the hood are numbered 171 and 17.
2,173,174, and the protrusions of the electrode frame are designated 181, 182 (173 not shown).

Each hood projection extends from the hood as a thin strip with a sharp tip such as 170 and curved toward the spray position 160. Projection part 1
Reference numerals 80 and 181 are sheet-like, and both similarly have sharp edges, but these tips are directed toward the hood itself. Since these protrusions are subject to the same electrical conditions as the hood and electrode frame, they can be made of the same materials as the hood and electrode frame. Advantageously, the projection is cast or formed in one piece with the hood or electrode frame. Alternatively, the protrusions may be added accordingly afterwards and fixed in a suitable manner.

During operation of the spray head, the spray ejected from the nozzle 111 is charged as described above, and the repelled spray is deposited as a liquid on the hood. The rebound spray can then fall as waste in large drops, which can even cause damage to the crop due to the excessive amount of chemical being delivered to one point. It is also conceivable that some of the spray may adhere to the electrode frame. In order to reduce the possibility of falling in the form of large drops, the protrusion is configured to direct the liquid towards the sharp end. These protrusions abut against the hood and the electrode frame to cause liquid to flow toward the sharp end, and the flow of liquid is controlled by the shape of these protrusions.

The liquid is subjected to a large electric field at the tip of the sharp ends of these protrusions. In the case of the protrusion of the hood, the liquid is grounded or grounded and falls from the tip, such as 170, in the form of small droplets due to the proximity of the space charge area on the charged spray. In the case of a protrusion of the electrode frame, the liquid is placed at a high potential with respect to the grounded or grounded hood and also falls from the sharp end as a droplet. These droplets can be as large as the larger particles of the spray atomized by the nozzle, but are in any case small enough to be considered part of the spray and droplets that fall from the spray head and are discarded. It will have a much smaller size. Although the hood is shown with a ground connection 121, this ground connection could be an actual wire or a conductive liquid, as explained with respect to Figure 1a.

Also shown in FIG. 5 is one advantageous form of electrical connection used to supply EHT to electrodes such as 148. In this embodiment, a plastic tube 151, such as PVC, is inserted into and projects from the stem of the electrode frame. A conductive rod 152, made of brass, for example, is housed within the tube 151 and projects from the tube 151 in conductive contact with the electrode 148. The tip 154 of the rod 152 is enlarged to form a plug that can engage a free EHT socket 155. On the pipe 151
O-ring 15 engages inside socket 155 to provide a watertight connection to prevent leakage of EHT.
3 is installed in the groove. Such a structure has been found to withstand immersion and maintain electrical connectivity.

The overall configuration of the hood and the protrusions does not necessarily have to follow the form described above, and the number or shape of the protrusions can be varied as desired. However, comb-shaped protrusions with multiple tips do not seem to be very effective. Nozzle 11
It has been found that tips such as 170 are more effective beyond the minimum distance from 1. This minimum distance position is fairly well defined. In the illustrated embodiment, the minimum distance is about 50 mm from the nozzle, beyond which liquid removal becomes effective for about 5 mm and remains effective for about a further 100 mm from this point.
In general, it appears to be more effective to have a small number of relatively elongated well-defined protrusions or tips than to have a large number of small tips. The reason may be that the latter configuration generates a stronger electric field. In many cases one or two protrusions or tips will be adequate.

Although the nozzle that ejects spray in a fan shape has been described above, it is of course possible to use a nozzle that ejects spray in other shapes such as a conical shape, and in that case, it will be necessary to change the shape of the hood appropriately.

A structure such as that described above reduces the problem that occurs when excessive amounts of liquid accumulate on the hood and form large liquid droplets on the hood and electrodes, reducing these droplets to droplets that can contribute as part of the spray. It can be reduced by changing. Waste of chemicals and potential crop damage are thereby avoided, and both material and processing effort are saved. In such a structure, the protrusion can be formed in the same casting or molding operation as the hood;
The spray head does not become more complex or more expensive.

For example, in a known structure described in British Patent Publication No. 1538931, an inductive charge adapter of a paint sprayer that uses air force is connected to an earthed shield.
shield), and the repulsive force caused by the electric field between the charged electrode and the shield specifically pushes the charged water droplets back into the spray. This is the opposite of the operation of the present invention, which is to attract the spray away from the electrode. However, the said British Patent Publication No. 1538931
It appears that the action of the shield described in the above patent may be non-uniform and may vary locally, so there is still the possibility that drops may return onto the electrode from another area. In the present invention, the marking spray is first collected and then disposed of.

[Brief explanation of drawings]

FIG. 1a is an illustration of the spray head of the present invention;
Figure 1b is a cross-sectional view of the spray head of Figure 1a;
2 is a block diagram showing a power supply circuit for a spray head such as that shown in FIG. 1a, FIG. 3 is a graph showing the performance of a known spray nozzle, and FIG. 4 is a graph showing the performance of the spray head of the present invention. FIG. 5 is a partial sectional view showing another spray head of the present invention;
6 is a side view of the spray head of FIG. 5; FIG. 10,110...Spray lance, 11,11
1...Nozzle, 20,120...Spray head, 21,121...Ground connection, 30,130...
...Hood, 31...Collector, 41, 42, 14
1,142... Electrode mounting member, 43, 48, 14
3,148...Electrode, B...Battery, HVC...
...Semiconductor DC/DC converter, REG...Adjuster, VC...
...Voltage comparator, AL... Alarm, Z... Zener diode, 171, 172, 173, 174
...Hood protrusion, 181, 182...Frame protrusion, 160...Spray, 152...Conductive rod, 155...Free EHT socket, 153
...O-ring.

Claims (1)

[Scope of Claims] 1. A spray head for a spray nozzle for dispersing an agricultural chemical liquid, the spray head being disposed in front of the spray nozzle and imparting an electric charge to droplets of liquid ejected from the spray nozzle. an electrode arrangement energized by a high voltage to create a charged electric field in front of the nozzle; a hood having a surface extending forward of the spray nozzle; an insulative mounting member for attaching the electrode arrangement; The mounting member is supported by a hood, isolating the electrode arrangement from the hood, and the hood is earthed or grounded and conductive, at least when actuated, to prevent return droplets. to prevent liquid droplets from returning to the electrode arrangement or to the insulative mounting member; and the hood has means for directing the trapped droplets for disposal. Spray head. 2. The spray head according to claim 1, which has means for easily attaching and detaching it from a spray nozzle or a spray lance. 3. The spray according to claim 1, characterized in that the electrode arrangement consists of opposing electrodes.
Head. 4. Spray head according to claim 1, characterized in that the hood is made of an electrically conductive material or has an electrically conductive surface. 5. Spray head according to claim 1, characterized in that the hood is configured to be grounded via the conductive liquid being sprayed. 6. A spray head according to claim 1, wherein the electrode arrangement changes the spray pattern emitted from the nozzle. 7. The spray head of claim 1, wherein the insulative electrode mounting member has a recess to prevent formation of a liquid path from the electrode to ground. 8. Spray head according to claim 1, characterized in that the means for disposing of trapped droplets is a trough attached to the hood. 9. The means for processing the captured droplets is characterized by being a protruding member that adheres to the hood and causes the captured droplets to fall as drops of the same size as the large droplets ejected from the nozzle. A spray head according to claim 1. 10. The spray head according to claim 9, wherein the projecting member is elongated and is integral with or separate from the hood. 11. Claim 9 or 10, characterized in that the at least one hood protrusion extends along the path of the liquid ejected from the nozzle and is close to a region having a spatial electric field during operation. Spray head described in any of the above. 12. The spray head of claim 1, wherein the elongated projecting member is integrally or separately attached to the electrode mounting member. 13. A spray head according to claim 9 or claim 12, characterized in that the at least one protruding member comprises an elongated member having at least one pointed end. 14. Claims 9 to 1, characterized in that the protruding member is made of an insulating material and is made electrically conductive by droplets of liquid deposited upon actuation.
4. The spray head according to any one of Item 3.