BACKGROUND

The present invention relates to a spraying device. More specifically, the present invention relates to a spraying device that includes both liquid and air nozzles for spraying plants. Even more specifically, the present invention relates to a spraying device that entrains a stream of atomised liquid in flanking swirling airstreams.

Various spraying devices that imparting rotation to atomised liquid emitted by spray nozzles are known. For instance:

WO94/13409 “Self-cleaning/unblocking spray nozzle” describes a liquid spray nozzle with swirl vanes for imparting rotation to atomised liquid exiting the spray nozzle.

US3,944,139 “Moisturizing apparatus for use with wind machines” describes a spraying device including: a mast; a fan comprising rotating blades for generating a swirling airstream; an array of liquid nozzles for introducing atomised liquid into the swirling airstream downstream of the fan; and means for rotating the fan about the mast.

GB780,589 “Improvements in apparatus for distributing insecticides and the like” and GB809,676 “Improvements in and relating to spraying apparatus for liquid insecticides and the like” describe a spraying device including: an air conduit; a nozzle disposed coaxially within the air conduit for introducing an atomised liquid into the airstream; and helical vanes/ wings associated with the liquid nozzle for imposing a vortex motion on I inducing rotation of the liquid exiting the liquid nozzle.

US3,301 ,485 “Method and apparatus for making frozen particles” and US5,908,160 “Centerbody for a two stream tangential entry nozzle” describe a spraying device including: an air conduit; helical vanes associated with the air conduit for inducing rotation of the air in the air conduit; and a liquid nozzle directed into the air conduit downstream of the helical vanes for introducing atomised liquid into the swirling airstream. US4,353,504 “High pressure snow gun” describes a spraying device including: an air conduit; a liquid inlet disposed coaxially within the air conduit for introducing an atomised liquid into the airstream; and helical vanes downstream of the liquid nozzle for inducing rotation of the stream of atomised liquid and air.

The object of the present invention is to provide a spraying device that includes a liquid nozzle flanked by a pair of air nozzles that are radially spaced from the liquid nozzle, thereby to entrain the atomised liquid within flanking swirling airstreams.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the invention, there is provided a spraying device that includes: a body; a first liquid nozzle on the body, for discharging a stream of atomised liquid; a first air nozzle on the body, for discharging a stream of air; a first vane associated with the first air nozzle for inducing rotation of the airstream exiting the first air nozzle; a second air nozzle on the body, for discharging a stream of air; and a second vane associated with the second air nozzle for inducing rotation of the airstream exiting the second air nozzle, characterised in that the first liquid nozzle is flanked by, and laterally spaced from the first and second air nozzles.

Typically: the first vane is disposed within either: the first air nozzle; or a conduit extending to the first air nozzle; the second vane is disposed within either: the second air nozzle; or a conduit extending to the second air nozzle.

Preferably: the first vane defines a right-handed helix; and the second vane defines a left-handed helix, thereby to induce contrarotation of the airstreams exiting the first and second air nozzles.

Generally, the spraying device further includes: a carriage on which the body is rotatably mounted; and means for oscillating the body relative to the carriage.

Typically, the spraying device further includes wheels rotatably mounted to the carriage.

Preferably, the spraying device further includes: a second liquid nozzle for discharging a stream of atomised liquid; a third air nozzle for discharging a stream of air; and a third vane associated with the third air nozzle for inducing rotation of the airstream exiting the third air nozzle, wherein the air and liquid nozzles are: alternately arranged along the body; and laterally spaced from each other.

Generally: the third vane is disposed within either: the third air nozzle; or a conduit extending to the first air nozzle; and the third vane defines a helix that induce rotation of the airstream exiting the third air nozzle that is counter to rotation of the airstream exiting the first or second air nozzle proximal the third air nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a side view of spraying device according to a preferred embodiment of the invention;

Figure 2 is a rear view of the spraying device in Figure 1 , in use;

Figure 3 is an enlarged view of section E in Figure 1 ; and

Figure 4 is a perspective view an air nozzle on the spraying device in Figure 1 .

DESCRIPTION OF THE INVENTION

With reference to Figures 1 to 4, a spraying device 10 according to a preferred embodiment of the invention includes: a housing 12, liquid nozzles 14 and air nozzles 16.

The housing 12 (generally referred to in the trade as a manifold) is an elongate member that extends operatively substantially vertically. The housing is rotatably mounted to a carriage 18 to which wheels 20 are, in turn, rotatably mounted. An oscillating means (not shown), in use, oscillates the housing 12 relative to the carriage 18, as the spraying device 10 is rolled along by the wheels 20. The carriage 18 includes: a reservoir 21 for storing liquid; a pump (not shown) for providing pressurised liquid from the reservoir to the liquid nozzles 14; and an air compressor (not shown) to provide compressed air to the air nozzles 16. Conduits (not shown) connect: the reservoir to the liquid nozzles 14; and the air compressor to the air nozzles 16. The liquid and air nozzles 14 and 16 are alternately mounted on the housing 12, spaced laterally from each other. More specifically, the liquid and air nozzles 14 and 16 are alternately arranged linearly along the housing 12, with the nozzles 14 and 16 directed substantially orthogonal to the housing 12. In use, the liquid and air nozzles 14 and 16 respectively discharge streams of atomised liquid and streams of air away from a lateral side of the housing 12. Typically, the streams of atomised liquid and air are directed parallel to, but spaced from one another. However, as these streams diverge, adjacent streams interfere with each other, causing turbulence.

Preferably, each pair of neighbouring nozzles 14 and 16 are spaced from each other by at least 130mm.

It will be appreciated that each liquid nozzle 14a is flanked by, and spaced from a pair of air nozzles 16a and 16b.

A vane 22 in the shape of a helix is associated with each air nozzle 16, with: the helix formed by each alternate vane 22 being like; and the helix formed by each pair of neighbouring vanes being opposed to each other. More specifically:

• the first vane 22a associated with the first air nozzle 16a is a right-handed helix;

• the second vane 22b associated with the second air nozzle 16b is a left-handed helix; and

• the third vane 22 associated with the third air nozzle 16c is a right-handed helix.

In use, the vanes 20 induce rotation of the airstreams emitted from the air nozzles 16. By alternating the vanes’ 20 helixes (i.e. between left and right-handed helixes), the airstreams exiting neighbouring pairs of air nozzles 16 rotate in opposite directions. This contrarotation induces significant turbulence at the interface between the adjacent airstreams.

The vanes 22 are either disposed within the air nozzles 16 or within the conduits extending to the air nozzles 16.

In use:

The spraying device 10 is driven (typically by a tractor) past plants (e.g. trees or crops) to be sprayed. • While being driven along, the housing 12 is oscillated by the oscillating means (i.e. alternatively rotated clockwise and counter-clockwise on the carriage 18 through about 40 degrees).

• The pump feeds pressurised liquid (including an insecticide) to the liquid nozzles 14, which liquid nozzles atomise the liquid and directs a stream of atomised liquid sideways I laterally from the housing 12 towards the plants.

• The air compressor provides pressurised air to the air nozzles 16. The vanes 22 (with alternating helical shapes, i.e. alternating between left and right-handed helical shapes) cause neighbouring air nozzles 16 to emit contrarotating airstreams that diverge as they travel from the air nozzles 16

• The stream of atomised liquid discharged from the liquid nozzles 14 similarly diverges as it travels from the liquid nozzles 14. As the stream of atomised liquid and the flanking airstreams diverge, they interfere with each other and cause the stream of atomised liquid to become entrained in, and be carried along by the flanking contra-rotating airstreams emitted by the flanking air nozzles 16.

• The turbulence induced by the contra-rotating airstreams causes the atomised liquid to move randomly, including in a direction back towards the housing 12, which random movement results in the plants being covered by the liquid (and insecticide) more effectively.

It will be appreciated that, whereas the spraying devices described in the prior art cause swirling of the atomised liquid, the spraying device 10 according to the present invention entrains the atomised liquid within the turbulent interface between adjacent rotating (preferably, contrarotating) airstreams, increasing the degree of random movement of the atomised liquid, and consequently coating the plants with the atomised liquid more effectively.