APPARATUS FOR PROPELLING ABRASIVE MEDIUM

Abstract: An apparatus for propelling an abrasive medium comprises a hand-held container (10) having an inner container (16) defining a cavity (16a) for a self-contained supply of the abrasive medium and a cavity (10a) for a self-contained propellant medium. The cavity (10a) connects with an abrasion resistant nozzle (24) with a venturi through a control valve (28), and the cavity (16a) also connects with the nozzle (24). Pressure on a cap (30) opens the valve (28) and passage of the propellant causes abrasive to be drawn to the nozzle (24). No abrasive therefore contacts the valve (28).

Description: - 1 - Apparatus for Propelling Abrasive Medium This invention- relates to apparatus for propelling a medium, especially an abrasive medium and in particul is concerned with hand held apparatus operable by H:' • oress-re. In previously proposed hand held devices for propelling such as abrasive medium, it has been necessary to connect the devices to an external ι supply of a propellent medium. Design problems have prevented the development of hand held cpparatu.s * of the aerosol type .for use with such as abrasive medium because of the effect of the medium on components such as valves. _ According to the present invention there is provided apparatus for propelling an abrasive medium, said apparatus having a first cavity for retaining a self-contained supply of the abrasive medium, and a second cavity for retaining a self-contained propellant medium, arid outlet means which comprises an abrasion resistant material and through which abrasive medium can be expelled from the apparatus, means being provided to enable the abrasive medium to be propelled through the outlet means by virtue of a manually applied pressure. Preferably the apparatus includes an outlet for said first cavity and an outlet for said second cavity ? - the first and second cavity outlets connecting with one another whereby, when the second cavity outlet is open, the propellant medium can pass therethrough and ca'use abrasive medium to flow - through said first cavity outlet and be dispensed through the outlet means. Alternatively, the apparatus includes an outlet for said first cavity and an outlet for said second cavity, said first ccvity including means enabling mixing of the abrasive medium with the propellant medium when the latter flows through the second cavity outlet * , whereby the mixture flows th.rough said first cavity outlet to the outlet means. Preferably also the second cavity outlet includes a valve for controlling passage of the propellant medium from the second ccvity, whereby there is no passage cf abrasive medium through the control valve. The outlet means nay be provided with a venturi and may be formed of a base material which is chromium plated so as to be abrasion resistant. The base material may be a hard plastics material such as nylon. The second cavity outlet may comprise a tubular component which enters the second cavity at a location so designed that in any disposition of the apparatus, propellant medium in c liquid form will not enter the - 3 - tubular component. Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:- _ " Fig. 1 is a vertical cross-section through a first embodiment of an apparatus according to the invention; and Fig. 2 is a vertical cross-section through a second embodiment of an apparatus according to the invention. Referring to Fig. 1 of the drawings, an apparatus in the form of an aerosol comprises a container 10, » preferably cylindrical, having a -concave lower -end cap 12 and an upper end cap 14, an outer edge of the latter being crimped onto the container 10 and an inner edge defining a central aperture. Located through the central aperture in the en-d ' cap 14, to extend into the container 10, is an arrange¬ ment comprising an inner container 16 preferably formed of a hard plastics material and defining a cavity 16a. The container 16 terminates short of the lower end cap 12 and is closed at its lower end by a plug 13. The cavity 10a surrounding the container 16 contains a liquid propellant medium as hereinafter described. At. the upper end, the container 10 is crimped together with a cover plate 20 onto the - ifi EA MPI - 4 end cap 14. Slidably mounted on the cover plate 20 to extend therethrough is a first tube 22 extending- within the container 16 close to the lower end thereof, and at its- upper end communicating with an outlet device or nozzle 24 for the aerosol. A further tube 26 extends through the cover plate 20 and has its upper end located in a valve 28, the latter also communicating with the nozzle 24. The tube 26 is bent at its lower end to extend through the wall of the inner container 16 and communicate with the cavity of the container 10. The position of the lower end of the tirbe 26 is carefully ' chosen as hereinafter described. The nozzle 24 at the outlet end thereof, downstrea of the locations of communication with the tube 22 and the- valve 23, is provided with, in the direction of flow, respective convergent and divergent parts forming a venturi . A cap 30 is mounted on the upper end of the nozzle 24 whereby when pressure is manually applied to the cap 30, the nozzle 24 is moved down¬ wardly with the tube 22, and simultaneously opens the valve 23, allowing communication between the cavity of the container 10 and the atmosphere. A one-way aperture 32 is provided in the cover plate 20 to provide communication between the atmosphere and the cavity of the inner container 16. The nozzle 24 is preferably formed of α hard plastics material such as nylon and, at least over the venturi section, is preferably chromium plated to provide an abrasion resistant lining. The tube 22 may also be abrasion resistant if necessary. A liquid propellant medium is introduced to the cavity of the container 10 to a level A. The medium is such as to produce a vapour which is contained within the remainder of the cavity of the container 10. The tube 26 has its lower end in communication with that part of the cavity- of the container 10 containing the propellant vcpour but, with the .valve 28 closed, the vapour • cannot pass to the nozzle 24. The inner container 16 is filled with an abrasive medium such as sand or shot, different grades of which are washed and sieved prior to being introduced into the container 16. The nozzle 24 with the valve 28 is biased to the closed position. When hand pressure is applied to the cap 30 to open the valve 28, the propellant vapour passes to the nozzle 24 and creates a reduction in pressure as it passes the upper end of the tube 22, whereby to draw the abrasive medium through the tube 22 and propel the abrasive medium through the nozzle 24. With this arrangement, the valve 28 is subjected only to the passage of the vapour or, in an extreme - o - condition, the propellant liquid, and is not therefore choked or fouled in any way by the passage of particulate material therethrough. As the valve 28 is not fouled by any particulate material, it will be apparent that the aerosol does not have to dispense its total content at any one time, because the valve can be re-closed. The tube 26 is so arranged that with the apparatus, in the horizontal position or in an inverted position, the amount of propellant liquid is such that it will still not reach the end of the tube 26 and pass therethrough. Referring to Fig. 2, similar components to the Fig. 1 embodiment- have received the same reference numerals for ease of identification. In this embodiment, the inner container 16 hcs a partition 34 extending thereacross towards the lower end, so as to define a chamber 36 between .the partition 3-- and the lower end cap 18. The partition 34 has a pressure operated one-way valve 38 formed to be abrasion resistant, enabling communication between the cavity of the inner container 16 and the chamber 36. An outlet tube 22a communicates at its upper end with an outlet device or nozzle 24a and extends through the inner container 16 to open at its lower end at the partition 34 into the chamber 36. The valve 28 communicates between the tube 26 and a further tube 40 - 7 - which extends back through the cover plate 20 and through the inner container 16, and opens through the partition 34 into the chamber 36. In use, when the valve 28 opens, the propellant vapour passes through the tube 40 into the chamber 36 where the vapour entrains the abrasive medium and moves the abrasive medium through the tube 22a so as to propel the abrasive medium through the nozzle " 24a. With this embodiment it will be appreciated that again the valve 28 is subjected only to the propellant vapour, or the liquid in an extreme condition, and is therefore not fouleS by the passage of any pcrticulate material therethrough. It is to be appreciated that where an aerosol is to be used with very light duty abrasive medium, it may be convenient to provide an apparatus where the abrasive medium is mixed with a liquid propellan-t medium and/or transmitted through the control valve. It will also be appreciated that the aerosol is not restricted in use to abrasive medium but can advcntageously be used with other particulate material, for example powders, particularly where it is preferred that the material does not pass through the control valve. - 8 - The apparatus is designed to be hand held and effectively provides a mobile and easily used abrasive blasting device which has many advantageous uses. For example, when filled with sand, the aerosol can - be used to etch security marks on car windows and the like and can also be used for cleaning of printed circuit boards. When filled with steel or iron shot, the aerosol can be used to remove rust marks in any equipment. Also the aerosol may be filled with cut wire shot and this is particularly suitable in peening of unaccessible areas of different forms of equipment. Various modifications may be made without departing from the invention. For example other types of aerosol equipment may be utilised with compressed air or other suitable propellant medium. The venturi section of the nozzle may be adjustably position relative to the remaining section of the nozzle.

Claims: - 9 - Claims 1. Apparatus for propelling an abrasive medium characterised in that said apparatus has a first cavity (16a) for retaining a self-contained supply - of the abrasive medium, and a second cavity (10a) for retaining a self-contained propellant medium, and outlet means (24, 24a) which comprises an abrasion resistant material and through which abrasive medium can be expelled from the apparatus, means (28, 30) being provided to enable the abrasive medium to be propelled through t.he outlet means (24, 24a) by virtue of a manually 'applied pressure. 2. Apparatus according to claim 1, characterised by an outlet (22) for said first cavity (16a) and an outlet (26) for said second cavity (10a), the first- and second cavity outlets connecting with one another whereby, when the second cavity outlet (26) is open, the propellant medium can pass there¬ through and cause abrasive medium to flow through said first cavity outlet (22) and be dispensed through the outlet means (24) " . 3. Apparatus according to claim 1, characterised by an outlet (22a) for said first cavity (16a) and an outlet (26, 40) for said second cavity (10a), said first cavity (16c) including means (38) enabling mixing of the cbrasive medium with the propellant OMPI - 10 - medium when the latter flows through the second cavity outlet (26, 40), whereby the mixture flows through said first cavity outlet (22a) to the outlet means. 4. Apparatus acco'rding to claim 2 or 3, characterised in that the first cavity outlet comprises a tubular .component (22 or 22a) which is formed of an abrasion resistant material. 5. Apparatus according to any of claims 2 to 4, • characterised in that the second cavity outlet (26) includes a valve (28) for controlling passage of the propellant medium from the second cavity (10c), whereby there is no passage of abrasive medium through the control valve (28). 6. Apparatus according to any of claims 2 to 5 characterised in that the second cavity outlet comprises a tubular component (26) which enters the second cavity (10a) at σ location so designed that in any disposition of the apparatus, propellant medium in a liquid form will not enter the tubular component (26). 7. Apparatus according to any of the preceding claims, characterised in that the outlet means (24, 24σ) is provided with a venturi. 8. Apparatus according to claim 7 characterised in that the venturi is formed in a section of the outlet means (24, 24a) which is adjustably positioned relative to the remaining section of the outlet means. - 1 1 - 9. Apparatus according to any of the preceding claims, characterised in that the outlet means (24, 24a is formed of a base material which is chromium plated so as to be abrasio'n resistant. 10. Apparatus according to claim 9 characterised in that the base material is a hard plastics material.

Inventors: EDGAR PAUL, TAYLOR DAN, EDGAR, PAUL, TAYLOR, DAN
Applicants: IMPACT TECH IRONVILLE LIMITED, IMPACT TECHNIQUES (IRONVILLE) LIMITED
Application year: 1982
Main classification: B65D83
IPC codes: B24C5, B65D83