Fluid sprinkling – spraying – and diffusing – Processes – Of discharge modification of flow varying
Patent
1993-06-04
1995-04-11
Grant, William
Fluid sprinkling, spraying, and diffusing
Processes
Of discharge modification of flow varying
239340, 2395903, 2395905, B05B 904, B05B 1100
Patent
active
054050847
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a valve, notably to a non-return valve which can also act as a filter for use in devices for forming sprays of droplets.
BACKGROUND TO THE INVENTION
Many forms of device have been proposed for dispensing fluids, for example medicaments, as sprays of fine droplets or aerosols. In some forms of device, it has been proposed that the aqueous solution of the medicament or other active ingredient be discharged through a fine orifice nozzle to form the spray using mechanical pressurizing means, for example using a compressed spring to drive a piston in a cylinder containing the fluid; in others, a pressurized gas is used as the propellant. For convenience the term pressurizing means will be used herein to denote all means by which the pressure required to dispense the fluid is generated and includes mechanical and pressurized gas operated means.
Where very small nozzle apertures, for example those having a diameter of 10 micrometers or less, are used to form fine droplets sizes, it is important to ensure that such small orifice apertures do not become blocked. It has therefore been proposed to provide a filter in the fluid discharge line upstream of the nozzle aperture. Small dimension filters are available, and these typically comprise a mesh or gauze which has a mesh aperture size as low as 3 micrometers or less. However, such filters are flimsy and therefore require some support means to prevent rupturing under the large pressures generated by the pressurizing means. Furthermore, such filters and their support means are additional and often expensive components.
There is, therefore, a continuing requirement for an effective and reliable filter capable of filtering fluid stream down to a very small particle sizes. In spray generating devices, there is usually also a requirement for a non-return valve positioned between the pressurizing means and the atomizing nozzle orifice so as to reduce the risk of residual fluid in the nozzle assembly draining back into the pressurization chamber and contaminating fluid held in a reservoir in the device.
We have devised a form of nozzle assembly incorporating a non-return valve assembly which provides a simple and effective means for reducing the risk of drain back of fluid from the nozzle assembly and may also be used to provide the functions of a filter and/or a filter gauze support in the nozzle assembly.
SUMMARY OF THE INVENTION
Accordingly, from one aspect, the present invention provides a nozzle assembly comprising a conduit in fluid flow communication with a nozzle aperture through which fluid is adapted to be discharged as a spray of droplets, characterised in that the effective minimum cross-sectional area of the conduit transverse to the line of flow of fluid at that point is selected so that flow of fluid through said conduit is restricted by the minimum effective cross-sectional area whereby back-flow of fluid from said nozzle aperture through said conduit at an ambient pressure differential and at an operational pressure differential is substantially prevented.
The invention also provides a spray generating device incorporating a nozzle assembly of the invention.
The term effective is used herein with respect to the cross-sectional area of the conduit to denote that cross-section of the conduit which is not occupied by an infill or other member, and through which fluid may flow. Thus, the conduit may be a fine bore tube, in which case the effective cross-sectional area is the cross-section of the fine bore. However, the conduit may also be in the form of a wide bore chamber into which is fitted a solid or hollow plug which reduces the free cross-sectional area of the chamber through which fluid can flow.
For convenience, the term upstream will be used herein to denote the direction opposed to a flow of fluid from the conduit to the nozzle aperture; the term discharge flow to denote a flow of fluid from the conduit to the nozzle aperture; and the term back flow to denote a flow of fluid from the nozzle aperture back to the conduit
REFERENCES:
patent: 460458 (1891-09-01), Bates
patent: 1035261 (1912-08-01), Strumpf
patent: 1838873 (1931-12-01), Scott
patent: 2432791 (1947-12-01), Osses
patent: 2676845 (1954-04-01), Rathsprecher
patent: 2772750 (1956-12-01), Bystricky
patent: 2786656 (1957-03-01), Corneil
patent: 2974880 (1961-03-01), Stewart et al.
patent: 3187748 (1965-06-01), Mitchell et al.
patent: 3319894 (1967-05-01), Coodrider
patent: 3330277 (1967-07-01), Gabriels
patent: 3396874 (1968-08-01), Malone
patent: 3421662 (1969-01-01), Hanson
patent: 3471065 (1969-10-01), Malone
patent: 3575322 (1971-04-01), Jordon
patent: 3605738 (1971-09-01), Ciranna
patent: 3628875 (1971-12-01), Wild
patent: 3790034 (1974-02-01), Horvath
patent: 3797748 (1974-03-01), Nozawa et al.
patent: 3831861 (1974-08-01), Hanson, Jr.
patent: 3838686 (1974-10-01), Szekely
patent: 3878973 (1975-04-01), Riccio
patent: 3921857 (1975-11-01), Riccio
patent: 3921861 (1975-11-01), Kondo
patent: 3923202 (1975-12-01), Riccio
patent: 3933279 (1975-01-01), Maier
patent: 4007855 (1977-02-01), Hierath et al.
patent: 4017007 (1977-04-01), Riccio
patent: 4147476 (1979-04-01), Warren
patent: 4167941 (1979-09-01), Capra et al.
patent: 4183449 (1980-01-01), Blake
patent: 4260082 (1981-04-01), Rooney et al.
patent: 4271875 (1981-06-01), Meshberg
patent: 4294410 (1981-10-01), Gueret
patent: 4345718 (1982-08-01), Horvath
patent: 4414972 (1983-11-01), Young et al.
patent: 4441634 (1984-04-01), Meshberg
patent: 4506497 (1985-03-01), Feuerlohn
patent: 4534345 (1985-08-01), Wetterlin
patent: 4648393 (1987-03-01), Landis et al.
patent: 4667668 (1987-05-01), Wetterlin
patent: 4693675 (1987-09-01), Venus, Jr.
patent: 4694977 (1987-09-01), Graf et al.
patent: 4810659 (1989-03-01), Higo et al.
patent: 4819834 (1989-04-01), Thiel
patent: 4860738 (1989-08-01), Hegemann et al.
patent: 4867347 (1989-09-01), Wass et al.
patent: 4875605 (1989-10-01), Weston
patent: 4892232 (1990-01-01), Martin
patent: 4896832 (1990-01-01), Howlett
patent: 5056511 (1991-10-01), Ronge
patent: 5088649 (1992-02-01), Hanson et al.
patent: 5110048 (1992-05-01), Waldrum
patent: 5115981 (1992-05-01), Callahan et al.
Dunne Stephen T.
Weston Terence E.
DMW (Technology) Limited
Grant William
LandOfFree
Nozzle assembly for preventing back-flow does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Nozzle assembly for preventing back-flow, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nozzle assembly for preventing back-flow will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1533689