GB2036601A - A portable apparatus for atomised spraying of liquid - Google Patents

Abstract

An apparatus, portable on the back of an operator, for atomised spraying of liquids, e.g. insecticides, comprises a motor and pump, mounted on a carrying frame, by which spray liquid and cold or heated compressed air are fed to an atomiser nozzle (20) along coaxial liquid supply and mixing tubes (25, 22), to mix in the small peripheral gap (42) between a flange (38) of a sleeve (39) and the inner wall of a tube (29) which is fitted in the end of the mixing tube (22). The air is given a vortical motion by curved vanes (32) prior to the mixing and the mixed air and liquid are emitted from a funnel (30) attached to the tube (29). A cup (50) coaxially disposed within the funnel (30) provides a small adjustable annular space (55) between its base (52) and the flange (38) through which the liquid flows radially to the mixing region (42). The flange (38) and the cup (50) have sharp edges (44, 59, 61) from which the whirling air draws off the liquid in droplets having a diameter of about 0.02 mm. <IMAGE>

Description

SPECIFICATION A portable apparatus for atomised spraying of liquid The invention relates to a portable apparatus for very fine atomised spraying of liquids in particular of fungicide or insecticide substances.

The Applicant Company has manufactured apparatus of this kind for many years. The invention is based on the problem of improving the degree of spraying of the liquid such that the spray jet leaving the mixing apparatus contains the liquid substance only in such small particles that these have substantially a diameter of 0.02 mm.

In order to overcome or alleviate this problem the invention provides a portable apparatus for atomised spraying of liquids comprising a driving motor and a pump connected therewith on a common frame, which apparatus produces a gaseous and a fluid flow whereby both flows are guided separately to a mixing apparatus, mixed together and sprayed therefrom characterised in that the mixing apparatus has two baffle faces arranged radially of the axis of spraying (A) and spaced apart in the axial direction, each having on their peripheral surface at least one mixing edge rotationally symmetrical to the axis (A). Particularly satisfactory spraying results from the use of a mixing and spraying cup within a conical spray funnel, the front of which cup is tapered to a sharp edge.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a side elevation of the apparatus in partly diagrammatic representation and in a section through its sound proof casing; Figure 2 shows a second side view turned through 900 in respect of Figure 1; Figure 3 shows the spray nozzle of the apparatus formed according to the invention to approximately normal size, partly in elevation and partly in axial longitudinal section; Figure 4 shows the spray head of the spray nozzle according to Figure 3 in section in its axial longitudinal section and to an enlarged scale; Figure 5 shows the twist body of the spray nozzle in side elevation; Figure 6shows in section on line VI-VI in Figure 5 and Figure 7 in its development;; Figure 8shows the shutter of the spray nozzle in its axial longitudinal section; Figure 9 shows the spray and mixing cup of the spray nozzle likewise in its axial longitudinal section, Figure 10 shows in its section on line X-X in Figure 9 and in rear side elevation; and Figure 11 shows a modified construction of the apparatus according to the invention with an additionally built-on combustion chamber for producing a hot-air jet usable in the spraying and atomising procedure.

The portable apparatus shown in Figures 1,2 and 10 is essentially intended for the very fine atomising of liquid serving for the protection of plants and is reproduced therein in one embodiment which can be carried by an operator on his back as desired or transported by hand.

The embodiment shown is constructed so as to be capable of being carried on the back and comprises a driving motor 1 and an air pump 2 which are fixed to a common frame 3. This frame 3 is mounted resiliently on a carrying frame 5 by means of swivel elements 4 whereby the resiliency of the swivel elements 4 is so determined that the vibrations of the mass which consists of the motor 1 and the pump 2 are not to be transmitted to the carrying frame 5 to a substantial extent. The unit consisting of the motor and the pump 2 is surrounded by a sound proof casing which consists of two shell-like halves 6 and 7. By this means the radiation of sound therefrom is dampened.

The entry of air for the cooling air of motor 1 is indicated at8 in Figure 1 and is formed as a resonator neck such that an emission of sound is substantially prevented. The cooling air emerges at the aperture 9 from the sound proof casing. This aperture 9 is likewise formed as a resonator neck and is directed substantially upwards so that any residual sound can escape upwards. In the lower region of the sound proof casing 6,7 small air bores (10) are arranged which contribute to the cooling of the inner space.

The carrying frame 5 has a back-plate 14 which is likewise formed as a damping member and substantially prevents the sound vibrations from within the casing 6,7 from being able to strike the body of the operator. These vibrations are reflected or absorbed by the back-plate. The air inlet 12 for the carburettor of the driving motor 1 which is an internal combustion engine, is located, as shown in Figure 2, on the upper side of the cooling air casing 6. Within inlet 12 there is located a resonator tube 13 which is provided with absorption means 15.

The exhaust gases of the internal combustion engine 1 are, as shown in Figure 2, led to exhaust via a sound absorber 16, which in the embodiment illustrated is arranged inside the sound proof casing 6, 7. Hereby further sound radiation is substantially prevented. In Figure 1 there is indicated in addition the fuel tank 17 of the internal combustion engine 1 and the active substance container provided for receiving the liquid to be sprayed is indicated at 18.

From the pump 2 a compressed air pipe 19 leads to the atomiser nozzle 20 described in more detail below and which is illustrated in detail in the Figures 3 to 10.

The atomiser nozzle 20 comprises a supply pipe 21 formed as a hand piece to which the compressed air supplied by the pump 2 is fed via a hose, not shown, and from there flows into a mixing tube 22 which is provided on its front end with a spray funnel 30. On the rear end of the mixing tube 22 is located a throttle valve 23 for adjustment of the quantity of the medium to be sprayed which is likewise supplied under pressure from the pump 2 to the throttle valve 23 via the pipe 24. From the valve 23 the spray medium proceeds via a central supply pipe 25, in the direction of the arrow 26 to the mixing and atomising head 28 shown in Figure 3 and enlarged in Figure 4.

The mixing and atomising head 28 contains, in a tubular extension 29 connected to the funnel 30, a twisting member 31 which is illustrated more precisely in detail in Figures 5 to 7, and serves to impart to the compressed air, before its outlet to the funnel 30, a circular motion about a longitudinal axis A of the central supply pipe 25 and mixing tube 22.

The twisting member 31 has four guide vanes 32 which are welded onto a tubular carrying piece 33.

This tubular piece 33 is, as shown in Figures 3 and 4, formed from the free end section of the central supply pipe 25. The conically formed front wall 34 of the tubular piece assists the whirling of the emerging spray medium. The guide vanes 32 run, in the region of their rear half, parallel to the common axis A of the mixing tube 22 and the central supply pipe 25, and merge in their front half in cylindrical curves 35, which deflect the compressed air current in the desired circular motion about the axis A. The deflection is enforced since the free edges of guides vanes 32 lie close to the inner wall of the bore of the extension 29 of the funnel 30.

The compressed air emerging between the guide vanes from the twisting member 31 is further compressed in a circular collecting chamber 37 in front of the flange 38 of a sleeve 39, which is shown in Figure 8 in longitudinal section with its hollow cylindrical shank press fitted, as can be seen in Figure 4, in a blind bore 41 of the central supply pipe 25 at its end section 33. The cylindrical edge 44 of the flange 38 of the sleeve 39 is adjacent the bore of the extension 29, with a small radial gap 42 therebetween so that the compressed air emerges from the collecting chamber 37 in the direction of the arrow 43 with considerable speed, and accordingly produces, at the outlet side of flange 38 a strong suction.

This, together with the measures described in more detail below provides for the very fine atomising of the spray medium.

The spray medium is introduced via a longitudinal bore 47, arranged in the bottom 46 of the sleeve 39 leading into the longitudinal bore 48 of the shank 49 of a mixing and atomising cup 50, which is illustrated in detail in Figures 9 and 10. The mixing and atomising cup 50 is formed pan-like on its end section to provide for the very fine atomising of the spray medium and has a cylindrical wall 51 which is connected via a bottom piece 52 running laterally of the general longitudinal axis A. The shank 49 carries in its middle section a screw-threaded 53 which is screwed into thread 54 in the sleeve 39 and allows the annual space 55 between the bottom 52 of the mixing and atomising cup 50 and the front face of the sleeve 39 opposite thereto indicated in the operating position in Figures 3 and 4, to vary axially and thereby adjust the atomising to an optimum.

The shank 49 contains, between the screw thread 53 and the bottom 52, six radial bores 58 through which the spray medium passes from the longitudinal bore 48 into the annular space 55. Under the infiuence of the compressed air current accelerated in the radial clearance space 42, the spray medium is driven radially outwardly and is strongly whirled on the sharp edge 59 which is formed by the bottom part 52 of the cup 50 and by its wall 51, and mixes and then flows together with the compressed air along the outerface of the wall 51 to a second sharp edge 61 at the front side of the wall 51, which edge is formed by a conical bore 62 on the front side of the wall 51.By this means there is caused a back circulation indicated in Figures 4 and 9 by arrow 62 with which a film of emulsion, not shown in the drawing, is guided back in the counter-direction to the inner bottom of the cup 50. In the bottom 52 there are provided, as shown in Figures 9 and 10, numerous apertures 63 through which the film of emulsion can arrive back in the annular space 55 between the bottom 52 and the front side 56 of the sleeve flange 38. By this means at the edge 61 of the cup 50 a very fine atomisation is achieved, and a mist-like mixing of the compressed air and the liquid leaving the funnel 30 is achieved whereby the liquid particles have a diameter in the order of magnitude of about 20 mm.

Whilst the apparatus hitherto described and illustrated in the drawings is mainly intended for the output of cold mist of cold aerosols and supplies the energy necessary therefor, Figure 11 shows an additional apparatus which provides an enlarged scope of use. By this means warm aerosols or thermal mist may be produced also. In this case there may be connected to an apparatus of the abovedescribed type, a combustion chamber 65 as shown in Figure 11. This combustion chamber receives fuel from a fuel tank, not shown, and through a pipe 67 the fresh air necessary for the combustion is fed. This combustion air may be branched off from the cooling air circuit as well as also from the pump circuit of the apparatus. The hot gases produced in the combustion chamber 65 are mixed with the compressed air at a connecting place 68 so that this can be heated to within any desired limits, for example up to 100 C and then for producing a thermal mist can be used with the atomiser nozzle 20 described above.

Claims (15)

1. A portable apparatus for atomised spraying of liquids comprising a driving motor and a pump connected therewith on a common frame, which apparatus produces a gaseous and a fluid flow whereby both flows are guided separately to a mixing apparatus, mixed together and sprayed therefrom, characterised in that the mixing apparatus has two baffle faces arranged radially of the axis of spraying (A) and spaced apart in the axial direction, each having on their peripheral surface at least one mixing edge rotationally symmetrical to the axis (A).

2. An apparatus according to claim 1, characterised in that the first baffle face is formed by a sleeve which is disposed in the direction of flow axially spaced from a twisting head provided with a least one curved guide vane on its peripheral surface.

3. An apparatus according to claim 1 or 2, characterised in that a mixing and spraying cup is provided projecting into the free opening of a hollow, conically shaped spray funnel, the front of which cup is tapered to a sharp edge.

4. An apparatus according to claim 3, characterised in that the cup has a tubular wall and a bottom extending crosswise to the axis (A), which bottom forms with the wall a sharp edge.

5. An apparatus according to claim 4, characterised in that the cup and the sleeve have means by which the axial space between the bottom of the cup and the front face of the sleeve is variable.

6. An apparatus according to claim 5, characterised in that the cup is connected to a shank carrying a screw thread thereon which cooperates with a thread in the sleeve.

7. An apparatus according to claim 6, characterised in that the shank of the cup contains a longitudinal bore which communicates with a bore in the bottom of the sleeve and with radial bores in the cup arranged in the vicinity of the bottom thread for the liquid flow therethrough.

8. An apparatus according to one of the claims 1 to 7, characterised in that directly in front of a mouth of a mixing tube, along which compressed air is led into a delivery funnel, a twist body is provided for imparting to the compressed air a circular motion.

9. An apparatus according to claim 8, characterised in that the twist body has a tubular part provided with several radially projecting guide vanes, which tubular part has a central longitudinal bore adapted to receive the sleeve and the cup, and is in connection with a supply tube for the liquid.

10. An apparatus according to claim 9, characterised in that the guide vanes have a first half of their length running parallel to the axis and have an end section curved cylindrically by means of which the compressed air is deflected tangentially and a rotary motion is imparted thereto.

11. An apparatus according to claim 10, characterised in that the free edges of the vanes lie close to the inner wall of a tubular extension of the spray funnel surrounding said vanes.

12. An apparatus according to one of the claims 1 to 11, characterised in that an additional device for producing a hot air current is provided.

13. An apparatus according to claim 12, characterised in that a combustion chamber adapted to produce a hot air current is provided and that the combustion chamber is operable with a cooling air current of the driving motor.

14. An apparatus according to one of the claims 1 to 13, characterised in that a sound proof casing encloses the air pump which casing consists of two shell-like parts.

15. Apparatusfortheatomisedspraying of liquids substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.