Atomizing dispenser

Details Atomizing dispenser Atomizing dispenser

1995-12-26

1997-08-05

Millin, Vincent

Surgery

Respiratory method or device

Means for mixing treating agent with respiratory gas

12820016, 12820315, A61M 1102

Patent

active

056532270

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a method of dispensing a flowable material in which a quantity of the material is entrained in a flow of gas and is atomised.
A particular use for such atomisation is in the dispensing of medicinal products where liquid or particulate material should preferably be finely atomised prior to inhalation, it being a known characteristic of inhalation therapy that its effectiveness is critically dependent upon the material being finely atomised in a controlled manner.
Other applications in which atomisation is important include the atomisation of fuel in fuel burners and internal combustion engines and the atomisation of water in humidifiers.
It is an object of the present invention to provide an improved method and apparatus for atomising liquids and particulate solids which provides atomisation in a controlled repeatable fashion together with entrainment of the atomised material in a flow of gas for delivery to a required site.
According to the present invention there is disclosed a method of dispensing a flowable material comprising the steps of supplying pressurised gas to a nozzle such that a flow of gas is discharged through an aperture defined between a lip of the nozzle and a diaphragm, introducing the material into the flow of gas such that material is entrained in the flow, and vibrating the diaphragm so as to atomise the material.
It has been observed that the effect of the vibrating diaphragm on the dispensed material is that atomisation is enhanced. In the case of liquid droplets, a fine mist can be produced in a repeatable fashion and by adjusting the dynamic characteristics of the diaphragm the distribution of droplet size can be tailored to meet specific user requirements in a variety of applications.
Preferably the diaphragm constitutes a wall of a chamber communicating with the aperture, the diaphragm being deformable in response to excess gas pressure in the chamber from a rest position to a displaced position in which the aperture is open to receive the flow passing between the lip and the diaphragm, the method comprising the steps of supplying compressed gas to the chamber such that the diaphragm is deformed into the displaced position and peripherally clamping the diaphragm such that it is maintained under tension in the displaced position whereby the diaphragm is vibrated by the flow of gas.
An advantage of this arrangement is that vibration of the diaphragm is excited and energised by the flow of gas without requiring any additional energy source to provide atomising vibration.
Preferably the diaphragm has an outer portion which defines said wall of the chamber, the lip of the nozzle being annular thereby defining a mouth of an outlet defined by the nozzle and which is traversed by a central portion of the diaphragm in the rest position, and wherein the method includes the step of biasing the diaphragm into contact with the lip when the diaphragm is in its rest position.
It has been observed that positively biassing the diaphragm and lip into contact with one another provides improved performance compared with arrangements in which either the lip remains spaced from the diaphragm in the rest position or in which the lip merely rests in contact with the diaphragm.
Preferably the method includes the step of applying a tensioning force to the diaphragm such that it is maintained under tension in both the rest position and the displaced position.
It is particularly advantageous that the diaphragm should be held in tension in this way if the contact with the lip is minimal or non-existent.
Conveniently ambient air may be admitted to the outlet via an opening defined in the central portion of the diaphragm.
This provides the advantage that ambient air may be drawn through the nozzle to be mixed with the discharged gas, a particular advantage when delivering material for inhalation therapy. A further advantage is that it avoids the formation of a resonant cavity between the diaphragm and housing which would result in damping of the vibration.
The vibrational characteris

REFERENCES:
patent: 3473530 (1969-10-01), Urbanowicz
patent: 5113855 (1992-05-01), Newhouse
Database WPI, 24 Mar. 1982, Derwent Publications Ltd., London, GB: AN B4027 .

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