GB2143750A - Spraying device separating liquids - Google Patents

Abstract

The device comprises a rotatable cone (12) whose apex extends into a liquid so that, on rotation, the liquid rises up the cone and is ejected radially in a spray. A shield (11) encloses the cone and has a slot (16) controlling the spray width and a flange (18) limits the axial extent of the liquid on the cone. The same principle is usable to separate immiscible liquids, since different liquids may be ejected from the cone at different axial locations. <IMAGE>

Description

SPECIFICATION Spraying device This invention relates to spraying devices and is especially applicable to devices for agricultural use.

Another valuable application of the invention is the spraying of very small volumes of liquids where even application is important such as the application of flavours and preservatives to foodstuffs (e.g.

crisps and muffins).

Spraying of chemicals in agricultural use (e.g.

herbicides) is commonly carried out by mixing the chemicals with large volumes of water and spraying through a nozzle. It is clearly more convenient to be able to spray more concentrated solutions more thinly and this is especially valuable where there is no easy access to large volumes of water.

Spraying devices are used, which utilise a disc which is spun at high speed to throw off a fine spray from the periphery of the disc. Such devices can be quite compact, but they have problems.

One particular problem is that the spray is uneven.

It is commonly required to spray a swath between crops and it is important that the spray should not spread to the crops. In practice, the greatest density of spray is along the edges of the swath and it has been shown that the edges could receive twice the chemical application received at the centre of the swath.

This problem can be corrected by using shields, as described by Taylor et al (Weed Research 1976.

17203-208). Another problem arises, however. The spinning disc has to be kept horizontal to avoid drift of the spray beyond the area required to be treated.

Attempts have been made to reduce drift by eliminating the smaller droplets, but this is insufficient to solve the problem. Due to the horizontal mode of operation, the droplets are in suspension for a longer period than with a pressure spray and Lane of the NIAE has reported that even with elimination of smaller droplets the drift is not appreciably reduced.

Directional spraying devices using the spinning disc principle have been produced. GB-A-2033252 uses a shield arrangement to produce a directional spray and the solution collected by the shield arrangement runs down into a reservoir. A pumpoperated recirculatory system is required to raise the solution from the reservoir to the spinning disc. As a result, the device is expensive and is too large to be hand held. Other devices operated on the same principle have the same problem.

The present invention provides a spraying device which operates without use of a pump and can be made compact for handheld use and can be made directional.

In accordance with this invention, a spraying device comprises a reservoir, a member having an outer surface which tapers from an upper portion with a relatively large circumference to a lower portion with a relatively small circumference, the lower portion extending into the reservoir, and drive means being provided to rotate the member about its axis extending from the upper to the lower portions, whereby, in use, solution is picked up from the reservoir by the rotating member and rises up the outer surface to form a spray at said upper portion.

The outer surface is preferably conical said lower portion being on apex.

It is preferred that a shield arrangement is provided defining an outlet slot around a part of said upper portion, the shield arrangement serving to direct excess solution back to the reservoir. The length of the slot may be variable by adjusting the shield arrangement.

An outward projection at the upper portion of the cone may direct the spray outwardly and may form a shallow channel around the outer surface.

The outer surface has to have surface characteristics such that the solution is held by the surface until it reaches said edge. The required texture of the surface will depend on the solution to be sprayed.

It has been found that the droplet size spectrum can be controlled in a narrow band as with a conventional spinning disc and also even application can be achieved, comparable with that obtained with nozzle spraying techniques.

Reference is made to the accompanying drawing which diagramatically illustrates a spraying device according to the invention.

The device comprises a conical housing 11 in which is mounted a solid conical member 12 for rotation about the cone axis. The member is carried by a shaft 13 which is driven by a motor (not shown).

The apex region of the casing defines a reservoir 14 for liquid to be sprayed. An inlet 15 is provided for the liquid. The apex of the conical member 12 extends into the liquid in the reservoir.

A slot 16 is provided in the casing, near the end opposite to the reservoir 14, and in alignment with the top of the conical member. The top of the member adjoins an outwardly extending peripheral flange 18 whose lower face is normal to the cone axis, although the angle to the cone axis may be different. The flange terminates in a downwardly extending lip 19, defining a peripheral channel 20.

In use, the conical member is rotated at a speed such that the member picks up liquid from the reservoir and the liquid forms a laminar flow up to the flange 18, where the liquid collects before leaving the lower edge of the lip 19 in a spray 21. A portion of the spray is thrown through the slot 16, which determines the width of spray, and the remainder runs down the casing back to the reservoir.

The device may be used in the attitude shown, in which the spray is ejected in a plane at an oblique angle to the ground directly at the region to be sprayed. This shortens the suspension time for droplets in the spray and renders control of the sprayed width easy with little, if any, drift.

The flange 18 and lip 19 may be omitted, so that an edge is defined at top of the cone by the top face of the cone. The provision of an arrangement forming a channel, such as 20, may facilitate formation of an even spray.

A spraying device of the type described may cover a spraying width of 1.5 metres with the application of as little as 0.5 ml. per second.

As stated previously different liquids are found to leave the cone surface at different levels. It is therefore possible to separate immiscible liquids by controlling the surface of the cone. The different liquids may leave the cone surface at different levels or one liquid may be ejected whilst another remains in the container.

Claims (7)

1. A spraying device comprising a reservoir, a member having an outer surface which tapers from an upper portion with a relatively large circumference to a lower portion with a relatively small circumference, the lower portion extending into the reservoir, and drive means being provided to rotate the member about its axis extending from the upper to the lower portions, whereby, in use, solution is picked up from the reservoir by the rotating member and rises up the outer surface to form a spray at said upper portion.

2. A spraying device according to claim 1, wherein the outer surface is conical and tapers to an apex.

3. A spraying device according to claim 1 or 2 including a shield arrangement defining an outlet slot around a part of the upper portion, the shield arrangement serving to direct excess solution back to the reservoir.

4. A spraying device according to claim 3, in which the shield has relatively adjustable parts to vary the length of the slot and hence the width of the spray produced.

5. A spraying device according to any preceding claim, wherein an outward projection is provided at the upper portion of the cone for directing the spray outwardly.

6. A spraying device according to claim 5, wherein the outward projection has a downwardly extending lip defining a shallow channel around said upper surface.

7. A spraying device substantially as herein described with reference to the accompanying drawings.