WO2010028455A1

WO2010028455A1 - Spray apparatus

Info

Publication number: WO2010028455A1
Application number: PCT/AU2009/001210
Authority: WO
Inventors: Murray Trevor Dagley; David J. Geekie
Original assignee: Chemical Technology Pty Ltd
Priority date: 2008-09-12
Filing date: 2009-09-14
Publication date: 2010-03-18

Abstract

Spray apparatus (10) including: a housing (20) defining a chamber (22) for liquid to be sprayed, which housing (20) has a gas intake (24) to admit and retain air or other gas as a pressure head (26) in said chamber for liquid therein, and a liquid port (28) for said liquid to exit said chamber due to the pressure head; a spray head (30) coupled to said liquid port (28) for receiving the exiting liquid and for selectively emitting the liquid as a spray driven by said pressure head; means for interchangeably receiving a self-contained pressurised gas tank (42); and means for recovering gas from said gas tank as a gas supply dedicated to said chamber, which means conveys gas from said gas tank to said chamber and is adapted to limit the pressure of gas introduced to said chamber.

Description

Spray Apparatus

Field of the invention

This invention relates generally to spray apparatus, especially such apparatus incorporated into mobile or portable spraying equipment. Such equipment is widely used for spraying paints, adhesives and horticultural chemicals, as well as for a wide variety of other purposes.

Background of the invention

The traditional form of mobile spraying equipment includes a tank for liquid to be sprayed which has an air intake to admit and retain air as a pressure head for the liquid. The pressurised air is typically sourced from an accompanying mobile or vehicle- mounted air compressor which in many cases also provides an air source at the spray head for atomising the liquid. Air compressors are a substantial item of equipment in themselves, are usually quite noisy, and require electrical power, a petrol engine or other external power source.

A known alternative to the use of an air compressor is a spray system with inbuilt disposable propellant packs. One such pack includes a tank about the size of a standard BBQ gas bottle containing as propellant a liquefied gas mixture such as propane/butane that is liquefiable at relatively low pressure. A danger with these systems is the flammable nature of the propellant. Non-flammable versions are available but have proven to be either very expensive or environmentally unacceptable. A further issue is that, once empty, the propellant containers are a waste item that is not readily reusable.

Chinese patent application CN 201020423 discloses a glue spray system in which air for the pressure head in the glue solution reservoir is delivered from a high pressure air tank that also supplies air to the spray head for atomising the liquid. The system is said to be for packing cigarettes and is thus an industrial scale installation. It is an object of the invention to provide spray apparatus that, at least in some applications, provides a useful, practical and versatile item of mobile or portable equipment.

Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.

Summary of the invention The present invention stemmed from a realisation that if the source of pressurised air could be dedicated to maintaining a pressure head, it was practical and feasible to replace the traditional air compressor, or problematical propellant packs, with interchangeable compressed gas tanks that are compact and portable.

The invention accordingly provides spray apparatus including:

a housing defining a chamber for liquid to be sprayed, which housing has a gas intake to admit and retain air or other gas as a pressure head in said chamber for liquid therein, and a liquid port for said liquid to exit said chamber due to the pressure head;

a spray head coupled to said liquid port for receiving the exiting liquid and for selectively emitting the liquid as a spray driven by said pressure head;

a means for interchangeably receiving a self-contained pressurised gas tank; and

means for recovering gas from said gas tank as a gas supply dedicated to said chamber, which means conveys gas from said gas tank to said chamber and is adapted to limit the pressure of gas introduced to said chamber.

The self-contained pressurised gas tank may typically contain air and is preferably of a size able to be carried by an individual, or at least transported on a trolley. A suitable interchangeably receivable self-contained pressurised air tank is a tank of a volume in the range 0.5 to 20 litre most preferably 2 to 8 litre, and able to be pressurised to around 50 to 300 bar, preferably 100 to 300 bar. Products already available and meeting this requirement are the pony or auxiliary tanks widely employed in scuba diving. By "self- contained pressurised gas tank" or "compressed air bottle" herein is meant a tank containing gas in its gaseous phase at a pressure substantially above atmospheric.

The means for recovering gas from the gas tank may be adapted to limit the pressure of gas introduced to the chamber by incorporating one or more regulators and/or relief devices to limit downstream pressure. The gas pressure for the pressure head may be around 0.5-5 bar, preferably 3-5 bar. The gas pressure will be dependent upon the viscosity of the liquid as well as the volume of liquid to be dispensed or sprayed.

Typically, the spray head will not have an external atomising air or other gas supply, and the self-contained pressurised gas tank is unavailable for this purpose as it is dedicated to the chamber that contains the pressure head during operation of the apparatus.

Brief description of the drawings

The invention will now be further described, by way of example only, with reference to the attached drawings, in which:

Fig. 1 is a schematic layout of spray apparatus according to a first embodiment of the invention;

Fig. 2 is a perspective view of a spray apparatus according to a second embodiment of the invention;

Fig. 3 is a cross-sectional side view of the spray apparatus of Fig. 2; and

Figs. 4A to 4C are cross-sectional side views similar to Fig. 2 illustrating the assembly of the spray apparatus. Detailed description of the embodiments

The illustrated embodiment of figure 1 is a spray apparatus 10 that has a housing or tank 20 defining a chamber 22 for a reservoir 25 of liquid to be sprayed, a spray head 30 coupled for receiving the liquid from chamber 22 and for selectively emitting the liquid as a spray 15, and a cradle mount 40 for interchangeably receiving a self- contained pressurised gas tank, typically a compressed air bottle 42.

Conveniently tank 42 is a 200 bar pony or auxiliary bottle of a kind widely employed as an emergency air supply auxiliary tank in scuba diving. These bottles are available in several sizes over the range 0.8 to 5.8 L; larger bottles could be used if incorporated in a trolley arrangement. It is emphasised that the invention is not limited to any specific self-contained pressurised gas tank.

Housing 20 has an air intake 24 to admit and retain air (or other gas) as a pressure head 26 in chamber 22 for liquid reservoir 25, a liquid admission port 29, and a liquid exit port 28 for the liquid to exit the chamber due to the pressure head 26. Liquid exit port 28 may typically be an open lower end of a dip tube 31 coupled to flexible tubing 33 that provides liquid communication to spray head 30. The port 28 may typically be disposed just above the bottom wall 21 of housing 20. In other arrangements, the liquid line could be taken, for example, directly downwardly from the bottom of chamber 22, or off the side at the bottom, as illustrated in an alternate embodiment in Figs 2 to 4, described below.

Spray head 30 would normally include a trigger valve 35 for releasing liquid and is generally of the type designed to atomise the liquid and to emit it as spray 15 driven by the pressure head 26, without its own source of atomising compressed air.

Cradle mount 40 includes a fitting 45 engaged by the outlet nozzle of compressed air bottle 42 when the latter is fully mounted in the cradle. Fitting 45 sealingly engages the outlet nozzle of the bottle and is coupled to air intake 24 via a high pressure air line 50. This line includes a pair of regulators 52,53 for stepping down the typically very high pressure of air in compressed air bottle 42 to the much lower pressure required to provide pressure head 26. A single dual stage regulator could be used in place of the pair of regulators 52, 53. For example, where bottle 42 has an initial air pressure when full of 200 bar, regulators 52 and 53 may be employed to step down the air pressure first to 8 bar then to 4 bar. The latter is a satisfactory pressure head for many spray liquids.

It will be appreciated that high pressure line 50 and its regulators 52,53 constitute means for recovering air from compressed air bottle 42 as an air supply dedicated to the chamber 22. It has been found that, because the compressed air bottle is so dedicated, and is not additionally required to supply atomising air to spray head 30, a single compressed air bottle initially at about 200 bar and of a standard volume in the range given can be employed to deliver all of the liquid contained in a 2OL chamber. Once a compressed air bottle has been exhausted, spraying may continue at the work site by interchanging the bottle for a full bottle.

An operator required to deliver the liquid at a work site need only travel to the work site with the illustrated spray equipment and a supply of compressed air bottles. At the end of a spraying session, the empty bottles may be readily refilled from a larger compressed air storage tank that may be carried on the operator's vehicle or be provided at the operator's work base or depot.

An alternate embodiment is illustrated in Figs 2 to 4, with like reference numerals being preceded by a 1. The spray apparatus 110 is produced as a single unit which is portable and able to be wheeled via castors 160. A lid 162 with handle 164 makes the unit easy to manoeuvre and incorporates a display 166 to assist in monitoring the liquid and/or gas levels.

The interchangeable air bottle 142 is received within the centre of an annular tank 120, that sits on a base 168, which the castors 160 are mounted from. As shown in Fig. 4A, when empty, the lid 162 locks into the base 168 for easy storage and transport. To use, the lid 162 is removed and a refillable liquid tank 120 is locked onto the base 168 via a bayonet fitting 170. The lid 162 also locks onto the top of tank 120 via a bayonet fitting 170. The high pressure line 150 is fitted to the tank 120 via a custom fitting 151 on the end of line 150. As best seen in Fig. 4B, the air bottle 142 is received within the centre of the annular tank 120. The lid 162 incorporates the high pressure line 150 and regulator 152 and locks onto the top of the air bottle 142. A standard airless spray hose fitting 172 attaches the tubing 133 of the spray head 130 to the tank 120. Pressure in the tank 120 forces liquid out of the tank outlet 174 into the tubing 133 for dispensing from spray head 130.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

CLAIMS:

1. Spray apparatus including:

means for interchangeably receiving a self-contained pressurised gas tank; and

2. Spray apparatus according to claim 1 , wherein the self-contained pressurised gas tank contains air.

3. Spray apparatus according to claim 2, wherein the self-contained pressurised gas tank is a size able to be carried by an individual, or at least transported on a trolley.

4. Spray apparatus according to claim 1 , 2 or 3, wherein the interchangeably receivable self-contained pressurised gas tank is a tank of a volume in the range 0.5 to 20 litre.

5. Spray apparatus according to claim 4, wherein said volume is in the range of 2 to 8 litre.

6. Spray apparatus according to claim 4 or 5, wherein the tank is able to be pressurised to around 100 to 300 bar.

7. Spray apparatus according to any one of the preceding claims, wherein the means for recovering gas from the gas tank is adapted to limit the pressure of gas introduced to the chamber by incorporating one or more regulators and/or relief devices to limit downstream pressure.

8. Spray apparatus according to claim 7, wherein the gas pressure for the pressure head is around 0.5 to 5 bar.

9. Spray apparatus according to any one of the preceding claims, wherein the spray head does not have an external atomising air or other gas supply, and the self- contained pressurised gas tank is unavailable for this purpose as it is dedicated to the chamber that contains the pressure head during operation of the apparatus.

10. Spray apparatus according to any one of the preceding claims, wherein the housing is an annular tank and the gas tank is received within the centre of the annular tank.