GB2033252A

GB2033252A - Rotary Disc Atomiser

Info

Publication number: GB2033252A
Application number: GB7935225A
Authority: GB
Original assignee: Trouw (UK) Ltd
Current assignee: Trouw (UK) Ltd
Priority date: 1978-10-10
Filing date: 1979-10-10
Publication date: 1980-05-21
Also published as: GB2033252B

Abstract

An atomiser having one or more (e.g. 1 to 10) rotary discs 1 for dispensing a liquid as droplets has an inlet aperture (6) at its base for liquid and a feeder (8) for distributing liquid to the disc or discs. The liquid is raised from the inlet 6 to the discs by a turbine 7 or by an Archimedean screw (11), Fig. 4 (not shown). The atomiser may be enclosed in a housing with a limited aperture to give directional spraying and the base of the housing may be a reservoir to facilitate recycle of liquid to the atomiser. <IMAGE>

Description

SPECIFICATION Spray Apparatus The present invention relates to rotary disc atomisers for dispensing a liquid in droplets.

Rotary disc atomisers are known. This type of atomiser dispenses a liquid over a circular area as a spray or mist consisting of small droplets of the liquid. The atomisers comprise at least one rotary disc which is contacted by the liquid to be dispensed, rotation of the disc resulting in a migration of the liquid to the periphery of the disc from which it is thrown off as a stream of droplets. The atomiser can have a plurality of discs. When more than one disc is present the discs are stacked one above the other. The known type of atomisers have an inlet aperture at the top and the liquid to be dispensed is fed downwardly through the aperture.

Difficulties have been encountered in these downwardly fed atomisers in distributing the liquid to the disc or discs. In particular when a plurality of discs are present the bulk of the liquid tends to be dispensed from the lowest disc only. It has been observed that the quantity of liquid dispensed from each disc is progressively less the higher the disc is placed in the stack. A number of proposals have been made in attempts to improve the distribution to the disc or discs of the liquid supplied to the atomiser. One such proposal is described in British Patent 1,361,564 in the name of British Petroleum Chemicals International Limited.

It is an object of the present invention to provide a rotary disc atomiser in which the distribution of liquid to the discs is facilitated and which can be readily adapted for directional spraying.

Accordingly the present invention is a rotary disc atomiser which comprises at least one rotary disc for dispensing a liquid as droplets, the atomiser having an inlet aperture at the base for the liquid to be dispensed and a feeder located within the atomiser for distributing the liquid to the disc or discs.

Discs for rotary disc atomisers are known and the known discs can be used in the present atomiser. Some examples of known types of discs are discs consisting of an annular strip the inner circumference of which defines a circular central aperture or the disc can be the outer rim of a dished plate like member. The periphery of the disc can be smooth or it can consist of a plurality of outwardly projecting teeth which facilitate the formation of droplets in the liquid to be dispensed.

More than one disc can be present. A convenient number of discs can be in the range 1 to 10.

It is a feature of the atomisers of the present invention that feeding the liquid to be dispensed upwardly from the base of the atomiser in combination with a feeder for distributing the liquid thus fed facilitates the use of a relatively large number of discs, thus increasing the capacity of the atomiser.

The size and/or configuration of the inlet aperture at the base of the atomiser for the liquid to be dispensed is not critical, however, for convenience it is usually circular or annular.

The feeder for distributing the liquid to the discs can comprise a tube having ports, (e.g. holes or slots) in the wall in the region of the discs through which liquid from inside the cylinder or tube can pass radially outwards into contact with the disc or discs. Alternatively, the feeder can be a funnel shaped member having a plain or grooved surface over which the liquid can pass into contact with the disc. The disc can form the outer rim of the funnel shaped member. The feeder can be formed as an integral part of the atomiser or it can be a separate member.

A device for inducing an upward flow of liquid from the inlet aperture through the feeder to the disc or discs can be located within the atomiser.

The device can be located within the inlet aperture and/or in the feeder. Some examples of suitable devices are turbines, Archimedean screws, or any type of impellor used in a centrifugal pump. Most suitably, when more than one disc is present in the atomiser, a plurality of such devices can be present in the feeder to assist in distributing the liquid to the discs.

The atomisers of the present invention can be readily adapted for directional spraying by enclosing them within a housing having an aperture in its wall through which liquid can escape in a predefined arc. Housings for adapting rotary disc atomisers for directional spraying are known. Any of the known types of housing can be used to adapt the atomisers of the present invention. In operation of the adapted atomisers, only a proportion of the liquid dispensed as the atomiser rotates escapes through the aperture in the housing. The remainder of the liquid is trapped within the housing and in the known type of atomisers in which the liquid to be dispensed is supplied downwardly through the top of the atomiser the liquid is allowed to run to waste.

However, in the atomisers of the present invention where the inlet aperture is at the base, the liquid trapped within the housing can be readily recycled back through the atomiser by providing a reservoir in the base of the housing in which the trapped liquid can collect and locating the inlet aperture of the atomiser in the liquid. The reservoir can be provided with an inlet for the liquid to be dispensed. A pump can be associated with the housing for feeding the liquid to be dispensed to the atomiser.

The present invention is further described with reference to and as illustrated in the accompanying drawings in which; Figures 1 and 4 are vertical sectional views of two atomisers.

Figure 2 is a sectional view along the line X-X of Figure 1.

Figure 3 is a vertical sectional view of a detachable feeder and atomiser base.

Figures 5 and 6 are perspective views of two housings for adapting the atomisers for directional spraying.

The atomiser shown in Figure 1 comprises an upper plate 2 and a lower plate 3 which forms an integral moulding with seven rotary discs 1. The upper plate 2 carries a rigidly attached rotatable shaft 4 by which the atomiser can be rotated. The shaft can be driven by an electric motor. The atomiser extends below the lower plate 3 as a tube 5 which is open ended at its base to provide an inlet aperture 6 for the liquid to be dispensed.

A fixed turbine 7 is located within the aperture at the bottom of tube 5. In operation the turbine rotates with the atomiser to pump the liquid to be dispensed upwardly in the atomiser into contact with a cylindrical feeder 8. The feeder has six vertical slots in its wall through which the liquid can then pass radially outwards into contact with the discs 1. An alternative type of demountable feeder is shown in Figure 3. The feeder is similar to that shown in Figure 1 but has holes 10 in place of slots and is moulded integrally with the basal tube 5 of the atomiser.

In operation of the atomiser shown in Figure 1 the inlet aperture 6 is placed in the liquid to be dispensed and rotation of the atomiser causes turbine 7 to pump the liquid to the feeder which distributes it via the slots 9 to the surface of the discs 1.

The atomiser shown in Figure 4 comprises an upper plate 2 and a lower truncated base region 3 and seven rotary discs 1. The upper plate 2 carries a rotatable shaft 4 which is rigidly attached to the plate so that rotation of the shaft rotates the atomiser. Concentric tubes 12 and 1 3 are located within the atomiser. The tubes have a cylindrical lower portion and a flared or truncated upper portion. The upper end of the inner tube 12 is attached to the upper rotary disc, the disc forming an upper rim of the tube. Similarly, the upper end of the outer tube 1 3 is attached to the lower disc which again forms an upper rim of the tube. The cylindrical lower portion of the tubes define an annular space, the bottom of which forms an inlet aperture 6 in the base of the atomiser for the liquid to be dispensed.The inner surface of the outer tube 13 is grooved to form an Archimedean screw 11. in operation, rotation of the atomiser causes the Archimedean screw to draw the liquid to be dispensed into the atomiser. The remaining discs have funnel shaped members 14 to 18 attached thereto the discs forming an upper rim of each funnel shaped member. The funnel shaped members 14 to 1 8 and the flared or truncated upper portion of tubes 12 and 1 3 form a feeder for distributing the liquid to be dispensed to the discs. They may be kept spaced apart by suitable projections and held together as a unit in any convenient manner. Optionally, the surfaces of the funnels and the truncated portion of tubes 12 and 13 can be grooved to facilitate the passage of the liquid.

In operation of the atomiser shown in Figure 4 annular inlet aperture 6 is placed in the liquid to be dispensed and the atomiser rotated. Rotation of the atomiser causes the Archimedean screw to draw liquid into the atomiser and raise the liquid to bring it into contact with the surfaces of the feeder which then distribute the liquid to the discs.

Figures 5 and 6 illustrate two housings which can be used to adapt the atomisers of the present invention for directional spraying. The housings shown in the figures comprise an upper region 1 9 with an aperture 20 through which liquid to be dispensed can escape from the housing. The lower region of each housing forms a reservoir 21 in which liquid trapped within the housing can be collected. The reservoirs are provided with inlets 22 through which the liquid to be dispensed can be supplied.

The upper region 1 9 of the housing shown in Figure 5 is volute shaped and the upper region of the housing shown in Figure 6 is cylindrical. The housing shown in Figure 6 has a baffle 23 and a slideable plate 24 by means of which the size of aperture 20 can be adjusted.

The atomiser is fixed inside the housing with its inlet aperture located in the housing reservoir. In operation of the adapted atomiser the liquid to be dispensed is fed to the reservoir of the housing through the reservoir inlet. Rotation of the atomiser causes the liquid in the reservoir to be drawn into the atomiser through the inlet aperture. The liquid is then distributed by the feeder to each disc from the periphery of which it is dispensed as droplets over a circular area. A small quantity of the liquid thus dispensed escapes from the housing through aperture 20 as a directional spray. The bulk of the liquid is trapped within the housing, collects in the reservoir and is then recycled through the atomiser.

Rotary disc atomisers according to the invention may be used for any of the known uses of such atomisers. It is particularly suitable for use in agriculture either for spraying harvested crops with preservatives or for spraying growing crops or land with pesticides.

Claims

1. A rotary disc atomiser comprising at least one rotary disc for dispensing a liquid as droplets characterised in that the atomiser has an inlet aperture at the base for the liquid to be dispensed and a feeder located within the atomiser for distributing the liquid to the disc or discs.

2. A rotary disc atomiser as claimed in claim 1 having from 1 to 10 discs.

3. A rotary disc atomiser as claimed in claim 1 or 2 characterised in that the feeder comprises a tube having ports in the wall in the region of the discs.

4. A rotary disc atomiser as claimed in claim 1, 2 or 3 characterised in that the feeder is a funnelshaped member having a plain or grooved surface over which the liquid can pass into contact with the disc.

5. A rotary disc atomiser as claimed in any of claims 1 to 4 characterised in that a device for inducing an upward flow of liquid from the inlet aperture through the feeder to the disc or discs is located within the atomiser.

6. A rotary disc atomiser as claimed in any of claims 1 to 5 characterised in that the atomiser is enciosed within a housing having an aperture in its wall through which liquid can escape in a predefined arc.

7. A rotary atomiser-as claimed in claim 6 wherein the housing has a reservoir for liquid in its base in which the inlet aperture for the atomiser is located.

8. A rotary atomiser as claimed in claim 1 substantially as described with reference to the accompanying drawings.