GB2506438A - Outlet for aerosol distribution range of nebulisers or atomisers - Google Patents

Abstract

The device increases the range that aerosols are broadcast from nebulisers without interfering with the aerosol generation process. The device generates an independent carrier airflow underneath the nebuliser aerosol output port. Air is drawn into the two separate channels 2, 2 of a conduit which is of greater cross sectional area at one end (the base) than the other (the top) by independently controllable fans 5, 5. Air drawn in at the base is forced to the top where the two channels merge just behind a hooded outlet. By controlling the relative airflows in the two channels turbulence and pulsing may be induced in the expelled carrier airstream which is directed on an upwards trajectory. This independent carrier airflow passes through the generated aerosol and carries it much further from the nebuliser than without the device.

Description

An Independent Device for Improving the Aerosol Distribution Range of Nebulisers and/or Atomisers.

TECHNTCAL FIELD

The present invention concerns improvements to the performance of nebulisers and/or atomisers (subsequently collectively termed nebulisers) designed for non-medical purposes.

BACKGROUND

It is known to create aerosols using ultra-sonic vibrations and carefully controlled air flows in a specially designed aerosol generating chamber (see for example patent application OB1 117119.6).

The efficiency with which such aerosol generating chambers convert liquids into aerosol particles less than 15 microns in diameter is closely related to the aerodynamics created within the chambcr. This relationship places restrictions on the extent to which the air flow through the chamber can be used to distribute the aerosol generated.

PROBLEM TO BE SOLVED

During our investigations, we have found that increasing the air flow through an aerosol generating chamber to seek an increase in the distance that the aerosol particles are distributed, away from the generation chamber, has a negative effect on the efficiency of aerosol particle generation within the aerosol generating chamber and more importantly jeopardises the integrity of the aerosol (dry-mist) production.

Furthermore, increasing the number of independent aerosol generating chambers at a central location does not increase the range of aerosol distributiom In short the problem to be solved is to increase the range of aerosol distribution from the aerosol generating chamber(s) without interfering with the aerosol generation process(s).

THE INVENTION IN BRIEF

The present invention resolves these difficulties while operating from a central location by co-ordinating the operation of a single or plurality of independent aerosol generating chambers (nebulisers) each tuned for maximum efficiency of aerosol particle (less than 15 micTons diameter) generation and each using an independently generated carrier airflow to broadcast the generated aerosol to much greater distances from the nebuliser than the nebuliser itself could achieve. This independently generated carrier airflow is achieved by externally mounting a directional airflow booster" on the nebuliser underneath the aerosol output port. This device creates and directs a strong, turbulent and directing airflow through the generated aerosol stream to carry the emitted aerosol to a much greater distance from the nebuliser than the unit itself without the "directional airflow booster" can achieve.

To achieve a sufficiently strong carrier airflow the "dfrectional airflow booster' thaws two completely independent airfiows into the base of a conduit and amplifies the flow rate of each of the separate airflow streams before merging them in a turbulence chamber behind its exit port, which directs the carrier stream through the nebuliser output on an upward trajectory away from the nebuliser.

The "directional airflow booster" associated with each aerosol generating nebuliser are independent of the aerodynamics of the nebuliser generating chambers, being reversibly attached to the external surface of the nebuliser(s) themselves or plumbed into a dedicated central consol / trolley, optionally used as a location for a plurality of nebulisers, and can therefore be increased or decreased in flow-rate to change the reach of the aerosol distribution without any effect on the efficiency of the aerosol generation process. The merging of two independent carrier airflows, the strengths of which are controllably variable with respect to each other, just prior to their emergence from the "directional airflow booster", greatly enhances the aerosol capture and carrying properties of the carrier airflow.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be discussed in detail using drawings I to 4 Drawing 1 Drawing 1 shows the directional airflow booster" which is basically a vertical conduit (1) partitioned into two channels (2 and 2' not shown in drawing 1 -see drawing 2) each possessing an independently controllable and multispeed fan to thaw air in at the base of the conduit and force both streams up the conduit to merge just prior to emerging at the top of the conduit by way of the only outlet (7) cut across one side of the conduit. The outlet (7) is surrounded by a hood (12) to improve the coherence of and direct the emerging air flow to leave the device on an upward trajectory at an upward angle of from 10 to 85 degrees from the horizontal, preferably from 20 to 65 degrees from the horizontal.

The overall shape of the "directional airflow booster", as shown in drawing 1, is not critical provided the area at the base of the conduit is at least twice the area at the top, that the emerging carrier airflow is directed in an upwardly direction, that the device is small enough to fit below the aerosol outlet of the nebuliser while leaving free airflow at the base.

The overall dimensions of the device may be tailored to suit the nebuliser being boosted but will normally fall within the general bounds of: a) overall height, 100 mm to 200 mm; b) depth. 50 mm to 150 mm; c) width, 25mm to 150mm. The outlet (7) stretches across the width of the conduit at its top with a height of from 5 mm to 20mm surrounded by a hood (12)5 nun to 30mm in depth and directing the emergent carrier airflow on an upward trajectory. The lower (bottom) and side edge's of the hood (12) may be from 20 mm to 30 mm wider than the top edge.

The device may be fabricated from any suitable engineering materials such as metals, plastics and polymers by any suitable process including blow-moulding.

Drawing 1 aLso shows the axis A B through which the cross-section shown in drawing 2 is taken.

Drawing 2 Drawing 2 shows a cross-section through the middle of the "directional airflow booster" (1) along the axis A ---B shown in drawing 1. It shows the internal partition (4) forming the separate channels (2 and 2') each possessing an independently controllable and multispeed impeller fan (5 and 5') to thaw air, optionally through air filter Units (6 and 6'), at the base of the channels, and force it up the, narrowing, channels until the two channels merge at the top of the conduit to form a region of turbulence "turbulence chamber" (8), behind the outlet (7) not shown in drawing 2 (see thawing 1), in which the separate airfiows merge. The positioning of the partition (4) is such as to approximately equalise the volumes of the formed separate channels (2 and2').

In order to amplify the flow of air pumped through the Ndirectional airflow booster" the total internal cross-sectional area of the device at the base is significantly greater than the area at the top. The ratio of the conduit cross sectftnal area between the top and the bottom (both channels) of the device should fall within the range I:L5 to 1:25 preferably 1:2 to 1:5.

The purpose of the two separate channels (2 and 2') is to enable turbulence to be generated within the emerging carrier airstream when the channels merge in the turbulence chamber (8) prior to exit, by controlling the airflow independently in the two channels. This is achieved by programming the separate fans (5 and 5') drawing the air into the separate channels to vary in speed both with time and independently between the channels. By this means both turbulence within, and pulsing of the carrier airflow stream is achievable.

The fans (5 and 5') are of any suitably sized and commercially available type capable of generating variable airfiows within the range 0.011 to 0.019 cubic meters per second, preferably 0.013 to 0.017 cubic meters per second.

Drawing 3 Drawing 3 shows the "directional airflow booster" (1) in its operational position in front and just below the output port (10) of a nebuliser (9), such as that disclosed in patent application GB 1117119.6. The "directional airflow booster" is reversibly attached to the nebuliser and held in position by any conventional means (11) such as clip and slot or magnetic attachment and may be controlled through the nebuliser control system or independently Drawing 4 Drawing 4 shows an alternative means of attaching the "directional airflow booster" to the nebuliser by the means of a trolley with a plurality platform trays. Each of the trays is designed to securely hold a plurality of nebulisers with retaining walls that have docking ports for the directional airflow booster" (1) and the services for both the nebulisers (electric) and the "directional airflow booster" (air and electric).

General discussion In a first embodiment the "directional airflow booster" (1) is attached, optionally reversibly, to the front of an aerosol generating nebuliser in such a position as to direct the formers booster carrier airflow from just under the latter's aerosol output port to pick-up and cany the aerosol further away from the nebuliser. The device is designed to ampli& the airflow it draws in, pulse it and use it to cany the separately produced aerosol further from its point of production than would otherwise be possible.

In a second embodiment, which is particularly suitable for distributing an aerosol throughout a large volume, a plurality of nebulisers are installed on a multi-platform trolley with their aerosol output ports pointing to all points on the compass. The retaining wall of each platfonn is designed to hold in position and service a "directional airflow booster" in the optimum position to carry the output from each of the nebulisers on that platform. The whole assembly of nebulisers and "directional airflow boostert' may be independently controlled in terms of both the level of air flow passing through each of the two channels in each "directional airflow booster" and the penodicity of the active and, optionally, inactive periods for each may be controlled and managed from a central consol on the trolley.