Fluid sprinkling – spraying – and diffusing – Processes – Including mixing or combining with air – gas or steam
Patent
1998-04-24
2000-03-14
Weldon, Kevin
Fluid sprinkling, spraying, and diffusing
Processes
Including mixing or combining with air, gas or steam
239159, 2394173, 2394245, 239432, B05B 120
Patent
active
060361034
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method and apparatus applicable to agricultural and horticultural and other spraying systems. The invention is particularly applicable to such spraying systems as disclosed in our prior patents and patent applications relating to boom-type sprayers having droplegs carrying spray nozzles. However, the invention is more widely applicable than to dropleg-type sprayers and is applicable to conventional spray-from-above sprayers likewise, and to lance and other hand-held sprayers for certain applications. An additional application of the invention is in harvesting machines such as potato harvesters for spray-treatment of the harvested crop and in related applications such as the spray-treatment of potatoes coming into or coming out of store.
BACKGROUND OF THE INVENTION
A problem which arises generally in relation to sprayers concerns effective penetration of the crop or other material to be sprayed, by the spray of droplets produced by the sprayer. Conventionally, various forms of spray nozzle are utilised in which a spray of droplets is produced solely by virtue of the energy derived from the supply of liquid under pressure.
However, such conventional arrangements do not achieve the level of crop penetration which can be desired.
Various attempts have been made to improve crop penetration including the use of air flow producing means in association with conventional spray nozzles. However, such an arrangement has been found to be bulky and relatively ineffective.
Attempts have also been made to utilise the effect of electrostatic charges to cause the sprayed droplets to be attracted to the crop material and deposited thereon. These also have been found to be relatively ineffective and have not been widely used.
The use of droplegs to permit crops to be sprayed from a low location generally below the canopy of leaves in the case of crops such as potatoes has been found to improve very substantially the ability to cover the under surfaces of plants, as compared with conventional spraying arrangements in which the droplets are discharged onto the canopy of leaves from above.
A further prior proposal known to the Applicants utilises an air supply in association with a liquid supply. However, the liquid supply is directed via a restrictor onto a baffle plate where primary atomisation occurs before the liquid is mixed with the compressed air. The compressed air then forces the thus-produced droplets through a circular passage onto an inner face of a flood jet. There, secondary atomisation takes place, prior to the spray emerging in a flat fan-shaped pattern. This dual stage atomisation process leads, so it is claimed, to the production of relatively large droplets in which air bubbles are trapped and which, by virtue of their size, are less subject to unwanted spray drift. It has been established that the droplets size thus produced is notably ineffective in effecting crop coverage. In practice, what is particularly wanted is the production of a droplet size similar to that which is produced in atmospheric conditions such as a misty morning in a damp climate overnight whereby the droplets which condense on surfaces such as the external surface of a standing car are of such a size that they have little tendency to roll over the surface, and they therefore stay where they are deposited. In combination with this objective, there is the corresponding need to be able to produce such droplets travelling at a sufficiently high velocity in order to penetrate the crop sufficiently.
Further prior proposals are disclosed in GB 952,457 and GB 1,378,190 and U.S. Pat. No. 4,465,832 and U.S. Pat. No. 4,179,068. These proposals involve systems for the admixture of liquid and air for liquid entrainment and/or droplet formation. The most pertinent of these with respect to the present invention is the latter U.S. Pat. No. '068 specification (assigned to NRDC) which discloses a liquid spray device in which liquid enters a swirl chamber in a generally radially inwardly-directed mann
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Benest Engineering Limited
Weldon Kevin
LandOfFree
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