AU4889200A

AU4889200A - Rotary atomisers

Info

Publication number: AU4889200A
Application number: AU48892/00A
Authority: AU
Inventors: John James Spillman
Original assignee: CEDAR RIDGE CONSULTANTS Ltd
Current assignee: CEDAR RIDGE CONSULTANTS Ltd
Priority date: 2000-07-27
Filing date: 2000-07-27
Publication date: 2002-01-31
Also published as: WO2002009885A2; WO2002009885A3

Description

P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

00.

*..00 0 Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: CEDAR RIDGE CONSULTANTS LIMITED John James SPILLMAN Freehills Carter Smith Beadle 101 Collins Street Melbourne Victoria 3000 Australia ROTARY ATOMISERS The following statement is a full description of this invention, including the best method of performing it known to us -1n_ Rotary Atomisers This present invention relates to rotary atomisers and in particular to rotary atornisers such as may be attached to moving vehicles or aircraft for spraying liquid.

Cotton and similar crops can be severely damaged by insect pests and this occurs well into the advanced stages of growth of the crop so that low clearance, land-based spraying systems are not practical. Thus spraying insecticides from aircraft is an attractive proposition. Spraying from aircraft may also be carried out for other purposes such as to kill weeds. However such sprays are subject to wind effects and severe drifting of the spray cloud can occur. It has been shown that this problem occurs to a possibly damaging extent when the spray drop diameters are less than about 250 urn.

Modemn aircraft cover a large area in a short time and therefore need to deliver insecticide in an appropriate forn at large flow rates. There therefore exists a real need for an atomiser which can be fitted on to agricultural aircraft and which can deliver large flow rates up to 10 litres, per mninute flying time) in a narrow band of dop diameter ofthe order of 250 um,.

B23I 20..B.32018 describes a hydraulically driven rotary atomniser for mounting on an aircraft.

A liquid to be sprayed is forced out of a nozzle located in the centre of a rotatable drum.

The liquid is ejected from the nozzle such tat it impinges substantially tangentially on the inner surface of the drum, causing the drum to rotate about its central axis. An annular plate disposed in the wall of the drum has a multiplicity of "V" 1 shaped grooves formed therein, such that the grooves pass from the inside to the outside of the drum for conducting fluid across the drum wall. The outermost ends of the grooves are shaped to provide points, a feature which facilitates droplet formation.

The inventor of the present invention has recognised that the "V" 1 shaped grooves of GB3233918 are oriented such that the transverse axes of the grooves are aligned wit the axis of rotation of the drum, and thus that the rotational force (due to the rotation of the drain and plate) tends to force liquid flowing along the grooves against the sidewalls of the grooves. This tends to disrupt the flow of liquid and broadens the range of drop sizes which are emitted from the tips of the grooves.

It is an object of the present invention to overomre or at least mitigate the disadvantages of known rotary atomisers. In particular, it is an object of the present invention to provide a rotary atomiser which facilitates the delivery of large flow rates over a narrow band of drop size.

According to a first aspect of the present invention there is provided a rotary atomiser comprising;, a drum rotatable about its longitudinal axis; a nozzle located inside of the drum such that the drum is rotatable about its axis relative to the nozzle, the nozzle being coupled in use to a liquid delivery system, wherein in use liquid exiting from the nozzle impinges on an inner surface of the drumcausing the drum. to rotate; a multiplicity of channels passing substantially radially through the drum for ****conducting liquid from the inside to the outside of the drum, the channels being substantially V-shaped in cross-section and oriented such that when the drum rotates in use, the narrower ends of the channels trail the wider ends.

In operation, embodiments of the present invention cause liquid passing through the Vshaped channels to be forced towards the narrow end (Or base) of the channels. This overcomes the problem noted above, and tends to facilitate the formation of drops having a relatively uniform size.

In a preferred embodiment of the invention, said drumn comprises a multiplicity of plates aligned in respective substantially axial planes. Said V-shaped channels are provided in the leading face (with respect to the direction of rotation) of each plate. More preferably, adjacent plates are in contact with one another so that the plates together form. a substantially cylindrical mnember.

Preferably, said nozzle comprises a substantially cylindrical housing having its longitudinal axis substantially co-axial with the axis of said drum. A multiplicity of nozzle holes are distributed about the housing and extend through said housing from the inside to the outside. The holes extend in a substantially transverse plane, at an angle to the radial direction. In use, liquid under pressure enters the inner space of the housing and exits through the holes so as to impinge on the inner surface of the drumn with a tangential directional component, causing the drum to rotate.

Preferably, a diffuser is contained within said housing for diffusing liquid entering the inner space. More preferably, the diffuser is substantially uylindrical and is c'o-axial wit the housing. The inner surface of the diffuser may taper outwardly from a first end coupled to a source of liquid to a second end which is open to said inner space of the housing.

The rotary atomiser may comprise a deflector plate located in a substantially transverse plane at one end of the drum. The plate is arranged such that in use it leads the drum when the vehicle or aircraft on which the atomiser is mounted is in motion, The deflector plate tends to deflect air around the space surrounding the outer surface of the drumi.

Preferably, said deflector plate has a plurality of holes distributed over its surface so that Ve 20 air can flow through the holes. More preferably, the diameter of said holes increases with radial distance from the axis of the drun.

Preferably, said V-shaped grooves terminate at the outer surface of said drum in, a tooth or point.

According to a second aspect of the present invention there is provided a rotary atomniser comprising: a drum rotatable about its longitudinal axis; a nozzle located inside of the drum such that the drum is rotatable about its axis relative to the nozzle, the nozzle being coupled in use to a liquid delivery system, wherein in use liquid exiting ffrm the nozzle impinges on an inner surface of the drum.

causing the drum to rotate; and a multiplicity of channels passing substantially radially through the drum for conducting liquid from the inside to the outside of the drum, wherein said nozzle comprises a substantially cylindrical housing having its longitudinal axis substantially co-axial with the axis of said drumn and a multiplicity of nozzle holes distributed about the housing and extend through said housing from the inside to the outside, said holes extending in a substantially transverse plane, at an angle to the radial direction.

In use, liquid under pressure enters the inner space of the housing and exits through the holes so as to impinge on the inner surface of the drumn with a tangential directional component, causing the drum to rotate.

9.***According to a third aspect of the present invention there is provided rotary atomiser comprising: a drum rotatable about its longitudinal axis; a nozzle located inside of the drum suich that the drum is rotatable about its axis relative to the nozzle, the nozzle being coupled in use to a liquid delivery system, *wherein in use liquid exiting from the nozzle impinges on an inner surface of the drum causing the drum to rotate; a multiplicity of channels passing substantially radially through the drum for conducting liquid from the inside to the outside of the drum; and a deflector plate located in a substantially transverse plane at one end of the drum, the plate being arranged such that in use it leads the drum when the vehicle or 99 aircraft on which the atomiser is mounted is in motion.

The deflector plate tends to deflect air around the space surrounding the outer surface of the drum.

Preferably, said deflector plate has a plurality of holes distributed over its surface so that air can flow through the holes. More preferably, the diameter of said holes increases with radial distance from the axis of the drum.

For a better understanding of the present invention and in order to show how the same may be carried into effect reference will now be made by way of example to the accompanying drawings in which: Figure 1 illustrates in axial cross-sectio'n a rotary atomniser; Figure 2 illustrates a nozzle housing of the atomiser of Figure 1; Figure 3 is a transverse cross-section the nozzle housing of Figure 2 Figure 4 shows in more detail a part of the cross-section of Figure 3;; Figure 5 illustrates a flow plate of the atomniser of Figure 1;P Figure 6 illustrates in more detail a part of the plate of Figure Figure 7 illustrates a cross-section on the lines B-B of Figure .3Figure 8 illustrates a cross-section on the lines A-A of Figure Figure 9 illustrates a section through the centre of a drum of the atomiser of Figure 1; and Figure 10 illustrates a deflection plate for use with the atomiser of Figure 1.

The following description concerns a rotary atomiser such as might be fitted, as part of an array of atomisers, to an aircraft for spraying crops with a liquid pesticide. However, The atorniser may also be fitted to other types of vehicles and may be used for purposes other than the spraying of insecticide.

As shown in Figure 1, the atomiser comprises a front attachment fitting 1 having a suitable threaded end to allow the atomiser to be fastened to standard spray booms of 0. agricultural aircraft and to receive fluid pesticides under pressure from a central o. reservoir. The diameter of the fluid supply hole is smoothly reduced in order to keep the diameter of the front bearing 2 of the atomiser small and therefore to keep the friction of the bearing small. Screwed into the end of the front attachment 11$s a cylindrical diffuser 4 which forms part of a nozzle 29,' the inside diameter of the diffuser 4 gradually increasing from the bottom end to the top, thereby reducing the axial velocity of fluid in the diffuser 4 as it flows towards the inner space of a nozzle housing 5. The lower end of this housing 5 is rigidly attached to the outer part of the diffuser 4.

The front attachment fitting 1, diffuser 4, and nozzle housing 5 remain stationary relative to one another in use.

Figures 2 to 4 show in more detail the nozzle housing 5. The housing 5 has 90 nozzle holes 12 formed therein, each hole being 0.5 nim in diameter with a recess 13 on the outer surface of 1.2 rum diameter. The nozzles are arranged in 5 helices (equally spaced round the circumference of the housing At a given axial position, five nozzles 12 S are equally spaced around the circumference of the cylinder 5. Moving from one end of the cylinder to the other, the holes are staggered by 240 between successive stations. As shown in particular in Figure 4, the nozzles are angled such that the fluid jets emerging from them tend to give a clockwise torque (when the atomiser is viewed from the bottom of the illustration of Figure The rear end of the nozzle housing 5 is firmly supported by the rear nozzle mounting 11. Press fitted onto the front attachment fitting :is a front ball race 2. The outer housing of thle front ball race 2 is pressed into a front plate retaining ring 3.

Forty five specially shaped grooved plates 6 ("flow" plates"), details of which are shown in Figures 5 to 9, are assembled to make a cylindrical drum 14 using a special jig to ensure that each face 15 of each plate is truly radial. The ends 16 of the grooved plates 6 *are held tightly together by the front plate retaining ring 3. Over the central 90mm. of each plate are a series of V-shaped grooves or channels 17, running from one edge 18 of the plate to the other edge 19. The grooves 17 are located in the leading Lace with respect to the direction of rotation of the drum. 14. Each groove is a 600 cut, 1.5 mm deep, pitched 2 nun apart. Viewed from the grooved face, the outer edge 19 of the plate 6 is cut to form a series of teeth 20, the points of the teeth corresponding to the lowest part of each groove 28 and having an angle of 400. At the outermost edge, the thickness of the teeth is tapered to zero at a 700 angle, In the assembled atomiser as viewed in Figure 1, the V-shaped channels are arranged on their sides as illustrated in Figure 7.

The outer face of the rear ball race 8 is pressed into the rear plate retaining ring 7. Thus, when the rear ball race 8 is pushed into its position on the shaft of the rear nozzle cylinder mounting 11, the rear plate retaining ring 7 encloses the ends 21 of the assembly of grooved plates 6. The faces 22 of the front and rear retaining rings 3 and 7 are slightly tapered such that as the nut 10 is tightened, pushing the rings 3,7 closer together, the grooved plates 6 are pushed tighter together to make the cylindrical drum 14. Between the nut 10 and the rear ball race 8, is the rear guard plate 9 which is of sufficient diameter to protect the rotating parts of the atomiser from damage if the whole is put down on a surface when not assembled on an aircraft.

The reason for giving the ends of the plates 9 a smaller base radius is to try to contain the film of fluid, formed by the jets on the bases of the plates 6 in the region of the grooves, so that as much as possible of it will escape down the grooves and not out of the ends towards the bearings 2,8. Again, to protect the bearings from receiving fluid, the diffuser rig 4 and the rear nozzle cylinder mounting 11I have large flanges 24,25.

Opposite these flanges, radial holes 26,27 are positioned around the front and rear plate *retaining rings 3,7 so that any fluid which does not reach that region is centrifuged out rather that entering the bearings. It is important to protect the bearings as much as possible in this way as seals cannot be used since the torque available from the angled *.15 jets 12 is limited and increased friction in the bearings would reduce the rate of rotation of the plate array increasing the size of the drops above that desfred, Alternative embodiments of the invention may use a) different numbers and sizes of plates 6, b) different numbers of grooves and teeth, e) different cross-sectional section size and shapes of grooves and, d) different numbers and diameters of nozzles. This would be necessary for example for atomisers designed for different flow rates or different mean drop size. It will be appreciated that other modifications may also be made.

A potential problem for rotary atomnisers is that, whilst droplets of a uniform and appropriate size may be emitted fromn the outer surface of the rotating drum, these droplets will be broken up upon contact with the fast moving outside air. To help alleviate this problem, a deflector plate may be attached to the atomniser in front of its leading edge to shield the atomniser from the air stream. Such a deflector plate is illustrated in Figure 10 (although only a part of the plate is shown in the Figure) and has a central opening which is used to mount the plate over the front attachment fitting 1 of the rotary atomiser so that the plate lies in a transverse plane with respect to the atomiser drum.

A large number of holes are provided in the deflection plate, arranged around a series of concentric circles. The diameter of the holes increases with radial distance from the centre of the plate. This construction allows drops emitted from the rotating drum to encounter a gradually increasing air flow rate as they move radially outward from the surface of the drum. This helps to prevent a breaking up of the drops which mnight happen were the drops to encounter air flowing at the Lull air speed immediately following emission from the drumi.

It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiment without departing from the scope of the present invention. For example, it will be appreciated that the grooves formed in the e *oflow plates need not have a p effect V-shape. For example, the bottom of the channel may have some finite width,

Claims

1. A rotary atomiser comprising: a drum. rotatable about its longitudinal axis; a nozzle located inside of the drum such that the drumi is rotatable about its axis relative to the nozzle, the nozzle being coupled in use to a liquid delivery system, wherein in use liquid exiting from the nozzle impinges on an inner surface of the drum causing the drum. to rotate; a multiplicity of channels passing substantially radially through the drum for conducting liquid from the inside to the outside of the drum, the channels being substantially V-shaped in cross-s ection and oriented such that when the drum. rotates in use, the narrower ends of the channels trail the wider ends.

2. An atonmiser according to claim 1, wherein said drum comprises a multiplicity of plates aligned in respective substantially axial planes, said V-shaped channels being provided in the leading face of each plate. 3I An atomniser according to claim 2, wherein adjacent plates are in contact with one another so that the plates together form a substantially cylindrical member.

4. An atomiser according to any one of the preceding claims, wherein said nozzle :9 comprises a substantially cylindrical housing having its longitudinal axis substantially co-axial with the axis of said drum, a multiplicity of no zzle holes being distributed about the housing anid extending trough said housing from the inside to the outside, the holes extending in a substantially transverse plane, at an angle to the radial direction.. An atomiiser according to claim 4 and comprising a diffuiser contained within said housing for diffusing liquid entering the inner space, the diffuser being substantially cylindrical and co-axial wit the housing.

6. An atomiser according to claim 5, wherein the inner surface of the diffuser tapers outwardly from a first end coupled to a source of liquid to a second end which is open to said inner space of the housing.

7. An atomiser according to any one of the preceding claims and comprising a deflector plate located in a substantially transverse plane at one end of' the drum.

8. An atonmiser according to claim 7, wherein said deflector plate has a plurality of holes distributed over its surface so that air can flow through the holes.

9. An atoniser according to claim 8, wherein the diameter of' said liules increascs with. radial distance from the axis of the drum. A rotary atomiser comprising: a drum rotatable about its longitudinal axis; *09 a nozzle located inside of the drum such that the drum is rotatable about its axis relative to the nozzle, the nozzle being coupled in use to a liquid delivery system, wherein in use liquid exiting from the nozzle impinges on an inner surface of the drum causing the drum to rotate; and a multiplicity of channels passing substantially radially through the drum for conducting liquid from the inside to the outside of the drum, wherein said nozzle comprises a substantially cylindrical housing having its longitudinal axis substantially co-axial with the axis of said drum and a multiplicity of 9....'nozzle holes distributed about the housing and extend through said housing from the inside to the outside, said holes extending in a substantially transverse plane, at an angle to the radial direction.

11. A rotary atorniser comprising: a drum. rotatable about its longitudinal axis; a nozzle located inside of the drum such that the drum is rotatable about its axis relative to the nozzle, the nozzle being coupled in use to a liquid delivery system, wherein in use liquid exiting from the nozzle impinges on an inner surface of the drum causing the drum to rotate; a multiplicity of channels passing substantially radially through the drum for conducting liquid from the inside to the outside of the drum; and -11- a deflector plate located in a substantially transverse plane at one end of the drum, the plate being arranged such that in use it leads the drum when the vehicle or aircraft on which the atomiser is mounted is in motion.

12. An atomiser according to claim 11, wherein said deflector plate has a plurality of holes distributed over its surface so that air can flow through the holes.

13. An atonmiser according to claim 12, wherein the diameter of said holes irnureases with radial distance from the axis of the drum.

14. A rotary atomiser substantially as hereinbefore described with reference to the accompanying drawings. DATED: 27 July 2000 Freehills Carter Smith Beadle Patent Attorneys for the Applicant: *se 9 *fee CEDAR RIDGE CONSULTANTS LIMITED esoc Of