GB2256817A

GB2256817A - Improvements in spraying apparatus

Info

Publication number: GB2256817A
Application number: GB9113558A
Authority: GB
Inventors: Anthony Robert Gascoyne Cecil
Original assignee: BILLERICAY FARM SERVICES LIMIT
Current assignee: BILLERICAY FARM SERVICES LIMIT
Priority date: 1991-06-21
Filing date: 1991-06-21
Publication date: 1992-12-23
Anticipated expiration: 2011-06-21
Also published as: GB9113558D0; GB2256817B

Abstract

The invention relates to improvements in spraying apparatus and in particular to apparatus for spraying chemicals such as agrochemicals in which it is important to maximise the contact of the chemical with the leaves and pest. The invention provides apparatus comprising a nozzle body in which there is a venturi through which the liquid is passed, a gas inlet to a convergent inlet end of the venturi enabling gas to be sucked into the stream of liquid, a mixing chamber at an outlet end of the venturi and a jet spray outlet. The resulting aerated droplets provide a better and more effective spray. <IMAGE>

Description

IMPROVEMENTS IN SPRAYING APPARATUS The invention relates to improvements in spraying apparatus and in particular to apparatus for spraying chemicals such as agrochemicals.

The spraying of agrochemicals to kill weeds and pests is a necessity for most farmers and the like.

Whilst some agrochemicals can be applied directly to soil to be absorbed through the roots of weeds or to kill pests inhabiting the soil it is necessary to apply some others directly to the leaves of the weed or to pests which are airborne or inhabiting plants.

In the spraying of agrochemicals, it is important to maximise the contact of the chemical with the leaves and pest. Traditionally it has been recognised that the best method of achieving this is by using very fine droplets of the chemical. This maximises the number of contact point because the number of droplets per volume of liquid is higher.

Also finer droplets tend to stick to the leaves or pests more easily.

The disadvantage in this procedure is that fine droplets tend to drift far more than coarser or heavier droplets and may cause damage or contamination of the adjacent environment. In the present age of environmental concern and the "green" movement, this is becoming less and less acceptable.

This disadvantage can be reduced by introducing air into the liquid before it is sprayed from the jet. This causes the droplets on the whole to be larger but aerated so that they do not use greater quantities of the chemical than a spray of finer droplets and it reduces the problem of drift. This method of spraying makes it possible to reduce the volume of water which speeds up the spraying operation as refills are not needed so frequently.

These aerated droplets also spread out and burst on contact with the leaf of the crop or the pest better than the ordinary coarse droplet or non-aerated fine droplet giving good coverage of the chemical being sprayed.

One spray jet is known which uses an air compressor to introduce air into the liquid and then relies on the liquid being sprayed by an anvil jet to give sufficient coverage. However, this known jet uses an air compressor to introduce the air to the chemical which requires another system of pipes to feed the air to each jet. Additional complications are rendered due to the need for air compression equipment, bulk and difficulty in transporation. The apparatus is also very expensive.

It is therefore an object of the invention to provide a jet assembly suitable for spraying agrochemicals and the like to overcome these disadvantages.

According to the invention there is therefore provided apparatus for spraying a liquid comprising a nozzle body in which there is a venturi through which the liquid is passed, a gas inlet to a convergent inlet end of the venturi enabling gas to be sucked into the stream of liquid, a mixing chamber at an outlet end of the venturi and a jet spray outlet.

According to the invention there is also provided a method of spraying a liquid comprising the steps of pumping the liquid to an inlet of a nozzle body from a reservoir, projecting a stream of liquid through a venturi in the nozzle body past a gas inlet in a convergent inlet end of the venturi thereby causing gas to be sucked in through the gas inlet, mixing the gas with the liquid and spraying the gas and liquid mixture through a jet spray outlet.

There will be now be described by way of reference to the accompanying drawings in which: Figure 1 is a sectional side elevation of a spray jet according to the invention; Figure 2 is an alternative embodiment of the spray jet of figure 1; and Figures 3a and 3b show yet another alternative spray jet, Figure 3b being a section on the line B-B of Figure 3a.

Referring first to figure 1, there is shown a jet spray 10. The jet spray device 10 comprises a generally cylindrical metering nozzle 11 which produces a jet of liquid from liquid supplied by a suitable reservoir into inlet 12. The nozzle projects the jet of liquid from outlet 13 into the tapered mouth 14 of a venturi pipe 15.

The venturi pipe 15 is generally cylindrical, with a partial bore 16 in one end. The metering nozzle 11 fits into the partial bore 16 and is held there by means of an adaptor 17. The metering nozzle 11 is held in position relative to the adaptor 17 by suitable means such as pressure fit or screw thread and the adaptor 17 is held relative to the bore 16 of the venturi pipe 15 by similar means.

The lower end of the partial bore 16 in the venturi pipe 15 opens into the aforementioned tapered mouth 14 which is the upper end of the venturi 19. A small bore 18 is drilled through the side of the venturi pipe 15 to the upper end of the tapered mouth 14 of the venturi 19, which acts as an air inlet.

Located beneath the venturi pipe 15 is a nozzle body 20 which has a mixing chamber 21 located directly beneath the venturi 19. At the end of the chamber 21 furthest from the venturi 19 is a jet spray outlet 22 which creates the fan pattern needed to spread the liquid ejected therefrom. The nozzle body 20 is held in position relative to the venturi pipe 15 by means of a cap nut 23.

For the device 10 to operate correctly the size of the metering nozzle 11 and the venturi 19 are dependent on the size of the jet spray outlet 22.

In operation, one or more jet spray device 10 are fixed to a spraying boom attached to a suitable vehicle. The jet spray device 10 is connected to the reservoir containing the chemical to be sprayed by known means. The chemical is then pumped into the inlet of the metering nozzle 11 which produces a stream of high velocity liquid which is projected into the venturi 19. Due to the increase in velocity of the fluid resulting from the venturi action and the kinetic energy of the fluid, air is sucked in through wall bore 18. The air and chemical are to a certain extent mixed during their progression through the venturi 19 and further mixing takes place in the mixing chamber 21 in the nozzle body 20.

Finally, the liquid and air mix is sprayed through the jet spray outlet 22 forming a fan pattern. The resulting droplets within the spray are not fine enough to cause drift, but burst easily on contact with the crop leaf being sprayed.

Figures 2, 3a and 3b show alternative embodiments of the jet spray device. Figure 2 is an arrangement in which the adaptor, the venturi pipe and the nozzle body combined into a single component 24 which includes the venturi 19 and jet spray outlet 22.

Figures 3a and 3b show yet an alternative arrangement in which the small bore 18 is replaced by a channel 25 in the top of the nozzle body 24, beneath the metering nozzle, the channel 25 opens into chambers 26 which in turn have outlets 27 to atmosphere.

The spray components can all be made from lightweight plastic or any other suitable materials and can be attached to standard spraying apparatus.

A number of the components can be standard pieces of equipment or adapted from such.

Obviously the invention can be used for spraying any liquid other than agrochemicals.

In an alternative embodiment of the invention, not illustrated, the venturi can be fitted into the liquid stream before each jet or made as a part of the jet assembly.

The venturi pipe could be used as a method of introducing air into the liquid stream which can feed an anvil jet, a cone jet, a double fan jet or any other suitable jet.

Claims

CLAIMS:

1. Apparatus for spraying a liquid comprising a nozzle body in which there is a venturi through which the liquid is passed, a gas inlet to a convergent inlet end of the venturi enabling gas to be sucked into the stream of liquid, a mixing chamber at an outlet end of the venturi and a jet spray outlet.

2. Apparatus as claimed in claim 1 in which the gas inlet is open to atmosphere, so that air is sucked into the stream of liquid.

3. Apparatus as claimed in claim 1 or claim 2 in which the mixing chamber forms the outlet end of the venturi.

4. Apparatus as claimed in any one of the preceding claims further comprising a metering nozzle having an outlet positioned adjacent the inlet end of the venturi for supplying a high velocity jet of liquid to the venturi.

5. Apparatus as claimed in claim 4 in which the metering nozzle is removable from the nozzle body.

6. Apparatus as claimed in claim 5 in which the metering nozzle is held in position in the nozzle body by means of an adaptor which is itself removable from the nozzle body.

7. Apparatus as claimed in claim 5 or claim 6 in which the size of the outlet of the metering nozzle and the size of the venturi are selected according to the size of the jet spray outlet.

8. A method of spraying a liquid comprising the steps of pumping the liquid to an inlet of a nozzle body from a reservoir, projecting a stream of liquid through a venturi in the nozzle body past a gas inlet in a convergent inlet end of the venturi thereby causing gas to be sucked in through the gas inlet, mixing the gas with the liquid and spraying the gas and liquid mixture through a jet spray outlet.

9. Apparatus as hereinbefore described with reference to and as shown in the accompanying drawings.