GB1564700A - Rotary atomisers - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO ROTARY ATOMISERS (71) I, EDWARD JULIUS BALS, an Austrian citizen, of Delamere House, Tedstone Delamere, Bromyard, Herefordshire, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to rotary atomisers and has particular, though not exclusive, application to crop-spraying equipment where there is a requirement for an atomiser which can be used for the spraying of a swath of substantially uniform width at a substantially constant spraying density. This requirement arises, for example, when applying a weedkiller to the strip of ground between two rows of a crop.

Rotary atomisers are known (see, for example, Patent Specification No. 1,515,511) which include a rotary element, such as a disc or plate, on to which, in use, liquid to be atomised is fed, rotation of the rotary element resulting in migration of the liquid to the periphery of the element and the issuance of a spray of droplets from said periphery.

Due to the fact that the horizontal deposition pattern of a rotary atomiser of the foregoing character operating about a substantially vertical axis is an annulus, it will be seen that the progression of such a pattern will not result in the deposit of a swath of anything like constant density and it is an object of the invention to provide a new or improved rotary atomiser which will fulfil the requirement referred to above.

According to the invention there is provided a rotary atomiser comprising a rotary element, means for feeding liquid to be atomised to the rotary element and from which it is thrown off in a substantially tangential spray, and a shroud for the rotary element which limits the angular extent of the area over which, in use, the droplets are projected, the shroud including two co-axial circumferential walls which are continuous for a given angular extent and are both rotatable relatively to a fixed structure of the atomiser, and relatively to one another, about their common axis, to permit controlled variation of the direction and width of the spray emerging from the atomiser.

Since the shroud which limits the aforesaid angular extent is adjustable to permit controlled variation of the direction and width of the spray emerging from the atomiser, the swath covered by the spray during linear movement of the atomiser may be set depending on, for example, the space between two rows of a crop.

The co-axial walls of the shroud may be of cylindrical form with the ends of the continuous portion thereof subtending an angle of 2700 at the axis of the cylinder. Said walls may be relatively rotatable about their common axis between two limiting positions in one of which the rotary element is completely shrouded and in the other of which spray droplets can issue from positions on the periphery of the rotary element spaced apart through 90 , the droplets being projected by the rotary element substantially tangentially thereof. Each wall may be rotatable through approximately 450.

The fixed structure of the atomiser may include means for mounting a pump in such manner that the driven member of the pump is rotated about the axis of the rotary element.

The arrangement may be such that the output shaft of an electric motor carries the rotary element intermediate its ends and has its free end connected to the driven member of the pump. In use, the axis of the rotary element will be vertical or inclined at a small angle to the vertical and one particularly advanageous disposition of the parts of the atomiser consists in mounting the electric motor above the rotary element and the pump beneath the rotary element so that the droplets which have been interrupted by said partcylindrical walls can drain gravitationally to a sump at the inlet side of the pump.

Thus, in use, the pump operates to draw liquid from the sump and deliver it along a supply line to a position adjacent the centre of the rotary element, which is preferably in the form of a disc or plate having a peripheral inclined wall formed with grooves along which5 in use, the liquid travels to the outermost edge of the disc or plate so as to issue as a spray of droplets from the edge of the disc or plate. The droplets travel in a tangential direction at a speed corresponding to the circumferential speed of the disc or plate, with the majority of the droplets striking the inner surface on one or other of the two walls forming the housing or shroud for the rotary disc or plate and being returned to the inlet side of the pump whereas the remainder of the droplets emerge through the segmental gap to form a spray band of controlled width.

The liquid is preferably fed from the pump to a chamber having an overflow and a delivery line terminating in a calibrated orifice disposed above the rotary element with the pump output greater than the rate of flow of liquid through the calibrated orifice so that liquid is continuously discharged from the chamber by means of the overflow and a substantially constant head of liquid is maintained in the chamber.

In order to avoid or reduce drift, the droplets preferably issue from the atomiser at a position close to the ground, for example, approximately six inches above ground level, and the segmental gap through which the droplets issue from the atomiser is preferably afforded by a parallel-sided slot in each of said cylindrical walls, which slots are spaced apart radially from one another and from the outermost edge of the rotary disc or plate whereby they act as a gate which allows the issuance only of droplets having a velocity in excess of a predetermined velocity. Thus, the distance by which the droplets are projected is confined to a range of approximately 5 to 10 cms. in width.

A plurality of atomisers may be mounted at longitudinally spaced positions on a boom, the opening of each shroud facing forwardly of the boom in the direction of advance of the latter with the spacing between the atomisers either such that spaced swaths are sprayed or such that the whole of the area traversed by the boom is sprayed at a substantially uniform spray density.

The atomisers may be connected to a storage tank on the boom with the liquid fed to the sump on the inlet side of the pump by way of a passage including a spring-loaded diaphragm controlling operation of a shut-off valve serving to maintain a substantially constant liquid level in the sump.

When the atomisers are used singly they are conveniently in the form of hand-held devices with a separate tank for the liquid, which tank may be strapped to the back of the user of the device. The device may incorporate a supply chamber containing a float valve for controlling the supply of liquid from the tank to the device, the tank then being vented to atmosphere. Alternative liquid supply arrangements may, however, be adopted. For example, a refillable feed bottle may be connected to the device, or the supply chamber of the device may be of such size as to accommodate an adequate volume of liquid.

The invention will now be described, by way of example, with reference to rotary atomisers as shown schematically in the accompanying drawings, in which: Figure 1 is a vertical sectional view of a first embodiment of atomiser, Figure 2 is a transverse sectional view of said atomiser.

Figures 3, 4 and 5 are vertical sectional views of second, third and fourth embodiments of atomiser, and Figure 6 illustrates the spraying pattern obtained in operation of any one of the atomisers.

The arrangement schematically illustrated in Figures 1 and 2 of the drawings includes a motor 10 having an output shaft 11 which is connected to a central spigot portion 12 of a disc 13 which has a peripheral inclined wall 14. The inner and outer surfaces of the wall 14 are grooved, with the inner surface grooves circumferentially staggered relative to the outer surface grooves. The disc 13 is connected by a shaft 15 to the driven member (not shown) of a pump 16 whereby operation of the pump 16 serves to draw liquid from a tube 17 surrounding the shaft 15 and to deliver it along a flexible pipe 18 so as to pass eventually to a position adjacent the centre of the disc 13.

A frusto-conical element 19 is connected to the upper end of the tube 17, the open mouth of the element 19 being secured in fluid-tight fashion to a container 20. The base 21 of the container 20 has a central spigot portion 22 in which the pump 16 is located.

A filler cap 23 fits over the spigot portion 22, the arrangement being that, when it is desired to fill the container 20 with liquid, the container is inverted and the filler cap 23 is removed. A cover 24 fits over the disc 13 and comprises a pair of annular elements 25 and 26 having cylindrical walls 27 and 28. The annular elements 25 and 26 are disposed in face-to-face engagement and each is rotatable relative to the motor 10 and container 20 through an angle of about 45 . The upper element 25 is formed with an arcuate slot (not shown) through which a projection (not shown) on the lower element 26 extends upwardly to permit manual manipulation of the positions of the two elements 25 and 26.

The cylindrical walls 27 and 28 are formed with parallel-sided circumferential slots 29 and 30, the ends of which subtend angles 900 at the common axis of the shafts 11 and 15.

One end of the slot 29 in the outer wall 27 carries a lip 31 and the opposite end of the slot 30 in the inner wall 28 carries a similar lip 32. The slots 29 and 30 are formed in the same horizontal plane as the upper edge of the inclined wall 14 around the disc 13 so that, as droplets are projected substantially tangentially from said edge, a selected proportion of the droplets will pass through the opening bounded by the two lips 31 and 32. The rate of rotation of the disc 13 is conveniently of the order of 2000 r.p.m., the size of the droplets being of the order of 300 microns and their velocity being such that they are projected a distance of approximately 60 cms.

assuming that the disc 13 is about 15 cms.

above the ground and neglecting drift. The two slots 29 and 30 will function as a gate such that droplets having a velocity less than a predetermined value will strike the lower edge of one or other of the slots so that the band width of the spray of droplets can thus be confined to between 5 and 10 cms., as shown in Figure 6.

As mentioned above, the annular elements 25 and 26 are each rotatable between positions as shown in Figure 2 in which the slots 29 and 30 are in complete register and positions in which they are out of register and the opening from the enclosure in which the disc 13 is disposed is completely closed. Adjustment of the positions of the elements 25 and 26 permits variation of the width of the swath that is sprayed, the maximum width being 60 a cms, as well as of the direction of spray. When the atomiser is at a given location, assuming that the common axis of shafts 11 and 15 is vertical, the spray issuing from the atomiser will cover an arcuate band of constant width and with a uniform spraying density. As shown in Figure 6, when the atomiser is advanced, in a direction centrally of the arc, a swath will be sprayed with a substantially uniform density. The degree of uniformity will, in fact, be slightly increased if said common axis is tilted slightly forwardly whereby the arcuate band is somewhat straightened.

The pump 16 is a centrifugal pump so that, when the motor 10 is first actuated and the disc 13 and the driven member of the pump 16 commence to rotate, the disc 13 will have attained its full operational speed by the time that liquid is projected thereon through the calibrated orifice at the free end of the pipe 18. In addition, when the motor 10 is switched off, almost immediate cessation of liquid delivery will be achieved whereby, by the time that the disc 13 comes to rest, substantially all of the liquid has been projected therefrom.

As can be seen from Figure 1, a substantially constant liquid head is maintained at the inlet side of the pump 16, this being ensured by making the container 20 a fluidtight fit with the frusto-conical element 19 (as mentioned above) and providing an aperture 33 in the tube 17 at a given height above the pump 16. Thus, air can only enter the inlerior of the container 20 when the level of the liquid in the tube 17 falls below the top of the aperture 33. The liquid passes from the pump 16 along the pipe 18 to a chamber 34 the top wall 35 of which is disposed adjacent the lower element 26 and is formed with a vent aperture. A tube 36 termi nating in a calibrated orifice extends from the chamber 34 to a position adjacent the centre of the disc 13 and the base of the chamber 34 is formed with an aperture in which a rubber grommet is fitted, the rubber grommet making sealing engagement with the wall of the aperture and with a vertical pipe 37. The pipe 37 is open at both ends and acts as an overflow, the output of the pump 16 being greater than the rate of flow of liquid through the calibrated orifice.

In operation of the device, the liquid drains back into the tube 17 after impinging on the inner surface of the cylindrical walls 27 and 28, and this liquid is supplemented by that flowing through the overflow pipe 37 which extends from the chamber 34 and enables a constant head feed to the disc 13 to be obtained. Adjustment of the head can be effected by pushing or pulling the pipe 37 relative to the rubber grommet. The liquid flowing through the overflow pipe 37 also acts as a diluent in respect of the possibly con taminated liquid draining back from the walls 27 and 28 and further dilution is effected bv fresh liquid flowing into the tube 17 through the aperture 33. Thus the concentration of any contaminant in the liquid is kept at a mini mum level.

In use, the device can be carried, somewhat in the manner of a suitcase, at a given height above the ground. Alternatively, one or more atomisers may be mounted on a boom carried on a wheeled vehicle whereby multi-swath spraying can be effected. The motors 10 of the atomisers are preferably battery-operated and suitable power packs may be provided.

The embodiments illustrated in Figures 3, 4 and 5 differ from that of Figures 1 and 2 in that alternative liquid supply means are provided. The other parts of the atomiser are identical and have accordingly been given the same reference numerals as have been used for the embodiment of Figures 1 and 2. In Figure 3, liquid is supplied to the base of the tube 17 from a chamber 38 containing a float 39 on which a shut-off valve 40 is mounted, the valve 40 opening when the level of liquid in the chamber 38 falls below a predetermined value to allow flow of liquid from an external source, such as a tank strapped to the back of the user of the atomiser, to the chamber.

In the embodiment of Figure 4, the liquid feed is instead obtained using a closed, refillable feed bottle 41 which is hermetically sealed to a pipe 42 connected to the tube 17 over the aperture 33. Air can pnly enter the bottle 41 when the level of liquid in the tube 17 falls below the top of the aperture 33 so that, regardless of the height of the feed bottle 41 above the pump 16, a substantially constant head of liquid will be maintained at the inlet side of the pump 16.

The provision of the float chamber 38 in the embodiment of Figure 3 is intended to enable a substantially constant head of liquid to be obtained at the inlet side of the pump 16. However, when a plurality of devices are mounted on a spraying boom and liquid is being fed thereto from a common supply, the arrangement shown in Figure 5 is more suitable. Liquid is fed from the common supply along a line 43 to a chamber 44 containing a spring-loaded diaphragm 45 and the diaphragm 45 carries a valve closure member 46 arranged to cooperate with a frustoXconical valve seat. The rating of the spring is such that, when the fluid pressure within the chamber 44 falls below a predetermined value, the diaphragm 45 moves upwardly under the action of the spring to move the valve closure member 46 out of engagement with the seat. On the other hand, when this pressure is obtained, i.e. when the liquid within the tube 17 reaches a predetermined level, the diaphragm 45 is deflected against the action of the spring and the valve closure member 46 moves into engagement with the valve seat.

WHAT I CLAIM IS: 1. A rotary atomiser comprising a rotary element, means for feeding liquid to be atomised to the rotary element and from which it is thrown off in a substantially tangential spray, and a shroud for the rotary element which limits the angular extent of the area over which, in use, the droplets are projected, the shroud including two co-axial circumferential walls which are continuous for a given angular extent and are both rotatable relatively to a fixed structure of the atomizer, and relatively to one another, about their common axis, to permit controlled variation of the direction and width of the spray emerging from the atomiser.

2. A rotary atomiser according to claim 1, wherein. the fixed structure of the atomiser includes means for mounting a pump in such manner that the driven member of the pump is rotated about the axis of the rotary element.

3. A rotary atomiser according to claim 2, wherein an electric motor is provided and has an output shaft which carries the rotary element intermediate its ends and has its free end connected to the driven member of the pump.

4. A rotary atomiser according to claim 3, wherein the electric motor is mounted, in use, above the rotary element and the pump is disposed beneath the rotary element so that the droplets which have been interrupted by the shroud drain gravitationalry to a sump at the inlet side of the pump.

5. A rotary atomiser according to claim 2, wherein the liquid is fed from the pump to a chamber having an overflow and a delivery line terminating in a calibrated orifice disposed above the rotary element.

6. A rotary atomiser according to claim 5, wherein the pump output is greater than the rate of flow of liquid through the calibrated orifice so that liquid is continuously discharged from the chamber by means of the overflow and a substantially constant head of liquid is maintained in the chamber.

7. A rotary atomiser according to any of claims 1 to 6, wherein each of the cylindrical walls forming the shroud is formed with a parallel-sided slot, which slots are spaced aparr radially from one another and from the outermost edge of the rotary element whereby they act as a gate which allows the issuance only of droplets having a velocity in excess of a predetermined velocity.

8. Spraying equipment comprising a plurality of rotary atomisers according to any one of the preceding claims mounted at longitudinally spaced positions on a boom.

9. Spraying equipment according to claim 8, and comprising a plurality of rotary atomisers according to claim 4, wherein the atomisers are connected to a storage tank on the boom with the liquid fed to each atomiser by way of a passage including a spring-loaded diaphragm controlling operation of a shut-off valve serving to maintain a substantially constant level in the sump for the supply of liquid to the rotary element of the atomiser.

10. A rotary atomiser according to any one of claims 1 to 7 in the form of a hand-held device with a separate tank for the liquid.

11. A rotary atomiser according to claim 10, wherein the device incorporates a supply chamber containing a float valve for controlling the supply of liquid from the tank to the device.

12. A rotary atomiser according to claim 1, wherein a refillable feed bottle is provided for supplying liquid to the rotary element.

13. A rotary atomiser according to claim 1, wherein the rotary element is contained within a device incorporating a supply chamber for the liquid.

14. A rotary atomiser substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

15. A rotary atomiser substantially as hereinbefore described with reference to and as shown in Figure 3, or Figure 4, or Figure 5 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

**WARNING** start of CLMS field may overlap end of DESC **. bottle 41 when the level of liquid in the tube 17 falls below the top of the aperture 33 so that, regardless of the height of the feed bottle 41 above the pump 16, a substantially constant head of liquid will be maintained at the inlet side of the pump 16. The provision of the float chamber 38 in the embodiment of Figure 3 is intended to enable a substantially constant head of liquid to be obtained at the inlet side of the pump 16. However, when a plurality of devices are mounted on a spraying boom and liquid is being fed thereto from a common supply, the arrangement shown in Figure 5 is more suitable. Liquid is fed from the common supply along a line 43 to a chamber 44 containing a spring-loaded diaphragm 45 and the diaphragm 45 carries a valve closure member 46 arranged to cooperate with a frustoXconical valve seat. The rating of the spring is such that, when the fluid pressure within the chamber 44 falls below a predetermined value, the diaphragm 45 moves upwardly under the action of the spring to move the valve closure member 46 out of engagement with the seat. On the other hand, when this pressure is obtained, i.e. when the liquid within the tube 17 reaches a predetermined level, the diaphragm 45 is deflected against the action of the spring and the valve closure member 46 moves into engagement with the valve seat. WHAT I CLAIM IS:

1. A rotary atomiser comprising a rotary element, means for feeding liquid to be atomised to the rotary element and from which it is thrown off in a substantially tangential spray, and a shroud for the rotary element which limits the angular extent of the area over which, in use, the droplets are projected, the shroud including two co-axial circumferential walls which are continuous for a given angular extent and are both rotatable relatively to a fixed structure of the atomizer, and relatively to one another, about their common axis, to permit controlled variation of the direction and width of the spray emerging from the atomiser.

2. A rotary atomiser according to claim 1, wherein. the fixed structure of the atomiser includes means for mounting a pump in such manner that the driven member of the pump is rotated about the axis of the rotary element.

3. A rotary atomiser according to claim 2, wherein an electric motor is provided and has an output shaft which carries the rotary element intermediate its ends and has its free end connected to the driven member of the pump.

4. A rotary atomiser according to claim 3, wherein the electric motor is mounted, in use, above the rotary element and the pump is disposed beneath the rotary element so that the droplets which have been interrupted by the shroud drain gravitationalry to a sump at the inlet side of the pump.

5. A rotary atomiser according to claim 2, wherein the liquid is fed from the pump to a chamber having an overflow and a delivery line terminating in a calibrated orifice disposed above the rotary element.

6. A rotary atomiser according to claim 5, wherein the pump output is greater than the rate of flow of liquid through the calibrated orifice so that liquid is continuously discharged from the chamber by means of the overflow and a substantially constant head of liquid is maintained in the chamber.

7. A rotary atomiser according to any of claims 1 to 6, wherein each of the cylindrical walls forming the shroud is formed with a parallel-sided slot, which slots are spaced aparr radially from one another and from the outermost edge of the rotary element whereby they act as a gate which allows the issuance only of droplets having a velocity in excess of a predetermined velocity.

8. Spraying equipment comprising a plurality of rotary atomisers according to any one of the preceding claims mounted at longitudinally spaced positions on a boom.

9. Spraying equipment according to claim 8, and comprising a plurality of rotary atomisers according to claim 4, wherein the atomisers are connected to a storage tank on the boom with the liquid fed to each atomiser by way of a passage including a spring-loaded diaphragm controlling operation of a shut-off valve serving to maintain a substantially constant level in the sump for the supply of liquid to the rotary element of the atomiser.

10. A rotary atomiser according to any one of claims 1 to 7 in the form of a hand-held device with a separate tank for the liquid.

11. A rotary atomiser according to claim 10, wherein the device incorporates a supply chamber containing a float valve for controlling the supply of liquid from the tank to the device.

12. A rotary atomiser according to claim 1, wherein a refillable feed bottle is provided for supplying liquid to the rotary element.

13. A rotary atomiser according to claim 1, wherein the rotary element is contained within a device incorporating a supply chamber for the liquid.

14. A rotary atomiser substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

15. A rotary atomiser substantially as hereinbefore described with reference to and as shown in Figure 3, or Figure 4, or Figure 5 of the accompanying drawings.