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Last Updated: March 28, 2024

Claims for Patent: 5,405,084


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Summary for Patent: 5,405,084
Title: Nozzle assembly for preventing back-flow
Abstract:A nozzle assembly which comprises a nozzle aperture for discharge of a fluid as a spray of droplets, and a conduit in fluid flow communication with the nozzle aperture. The flow of fluid through the conduit is restricted by the minimum effective cross-sectional area of the conduit transverse to the line of flow of fluid through the conduit so that back flow of fluid from the nozzle aperture through the conduit at ambient and operational pressure differentials is substantially prevented. The invention further provides for a method of discharging a fluid as a spray of droplets, and a spray generating device which includes the nozzle assembly of the present invention.
Inventor(s): Weston; Terence E. (Stradbroke, GB2), Dunne; Stephen T. (Ipswich, GB2)
Assignee: DMW (Technology) Limited (GB)
Application Number:08/070,306
Patent Claims: 1. A spray generating device, comprising:

pressurizing means for applying a predetermined amount of energy to a metered quantity of fluid in order to subject the fluid to a predetermined increase in pressure by transitioning from a loaded configuration to a rest configuration;

retaining means for retaining said pressurizing means in said loaded configuration;

releasing means for releasing said retaining means so that said pressurizing means transitions from said loaded configuration to said rest configuration to thereby subject the fluid to said predetermined increase in pressure; and

a nozzle assembly which comprises a nozzle aperture for discharge of the fluid as a spray of droplets, and a conduit in fluid flow communication with said nozzle aperture, wherein the flow of fluid through said conduit is restricted by the minimum effective cross-sectional area of said conduit transverse to the line of flow of fluid through said conduit, wherein transitioning said pressurizing means from said rest configuration to said loaded configuration creates suction, said suction being insufficient to cause back-flow of fluid from said nozzle aperture into said conduit.

2. A spray generating device as claimed in claim 1, wherein said conduit comprises a fine bore tube and said effective cross-sectional area is the transverse cross-section of said fine bore tube.

3. A spray generating device as claimed in claim 2, further comprising: a filter element.

4. A spray generating device as claimed in claim 1, wherein said conduit comprises a chamber of greater cross-sectional area than said nozzle aperture, and further comprising a static infill member located within said conduit so as to occupy at least part of the cross-section of said chamber.

5. A spray generating device as claimed in claim 4, wherein a first passageway is formed between an end wall of said conduit and an end wall of said infill member.

6. A spray generating device as claimed in claim 5, wherein said chamber comprises an axial chamber having a blind end, said nozzle aperture located adjacent said blind end of said axial chamber, and said infill member is substantially congruent with an internal transverse end wall of said blind end of said axial chamber and is a clearance fit therein to form said first passageway.

7. A spray generating device as claimed in claim 5, wherein a second passageway is formed between a side wall of said conduit and a side wall of said infill member.

8. A spray generating device as claimed in claim 7, wherein said chamber comprises an axial chamber having a blind end, said nozzle aperture located adjacent said blind end of said axial chamber, and said infill member is substantially congruent with an internal side wall of said blind end of said axial chamber and is a clearance fit therein to form said second passageway.

9. A spray generating device as claimed in claim 7, wherein flow of fluid through said nozzle assembly is substantially prevented when a pressure differential substantially equal to 0.2 bar is applied across said nozzle assembly.

10. A spray generating device as claimed in claim 7, wherein the minimum cross-sectional dimension of said second passageway is less than the maximum dimension of said nozzle aperture, wherein said second passageway serves both as a flow restrictor to reduce back flow of fluid and as a filter for said fluid flowing through said nozzle assembly.

11. A spray generating device as claimed in claim 5, wherein the minimum cross-sectional dimension of said first passageway is less than the maximum dimension of said nozzle aperture, wherein said first passageway serves both as a flow restrictor to reduce back flow of fluid and as a filter for fluid flowing through said nozzle assembly.

12. A spray generating device as claimed in claim 1, wherein flow of fluid through said nozzle assembly is substantially prevented when a pressure differential substantially equal to 0.2 bar is applied across said nozzle assembly.

13. A spray generating device as claimed in claim 1, further comprising: a filter element.

14. A method of discharging a fluid as a spray of droplets, comprising the steps of:

loading a pressurizing means by transitioning said pressurizing means from a rest configuration to a loaded configuration;

retaining said pressurizing means in said loaded configuration;

transitioning said pressurizing means from said loaded configuration to said rest configuration to thereby subject a metered quantity of fluid to a predetermined increase in pressure; and

flowing the fluid through a nozzle assembly which comprises a nozzle aperture for discharge of the fluid as a spray of droplets, and a conduit in fluid flow communication with said nozzle aperture, wherein the flow of fluid through said conduit is restricted by the minimum effective cross-sectional area of said conduit transverse to the line of flow of fluid through said conduit, wherein said loading step creates suction, said suction being insufficient to cause back-flow of fluid from said nozzle aperture into said conduit.

15. A method as claimed in claim 14, wherein said flowing step is performed so that the flow of fluid through said nozzle assembly is substantially prevented when a pressure differential substantially equal to 0.2 bar is applied across said nozzle assembly.

16. A spray generating device, comprising:

a spring-loaded pump mechanism, wherein transitioning said pump mechanism from a loaded configuration to a rest configuration applies a predetermined amount of energy to a metered quantity of fluid in order to subject the fluid to a predetermined increase in pressure and transitioning said pump mechanism from said rest configuration to said loaded configuration creates suction;

retaining means for retaining said pump mechanism in said loaded configuration;

releasing means for releasing said retaining means so that said pump mechanism transitions from said loaded configuration to said rest configuration to thereby subject the fluid to said predetermined increase in pressure; and

a nozzle assembly which comprises a nozzle aperture for discharge of the fluid as a spray of droplets, and a conduit in fluid flow communication with said nozzle aperture, wherein the flow of fluid through said conduit is restricted by the minimum effective cross-sectional area of said conduit transverse to the line of flow of fluid through said conduit, wherein the suction created by transitioning said pump mechanism from said rest configuration to said loaded configuration is insufficient to cause back-flow of fluid from said nozzle aperture into said conduit.

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