Inhaler

Abstract

An inhaler comprising a source of inhalable composition. An outlet flow path is provided for the composition from the source to a composition outlet at an outlet end of the inhaler. Means are provided to generate a flow of composition from the source along the outlet flow path and out of the composition outlet when suction is applied to the outlet end. A pair of air outlets at the outlet end are arranged on opposite sides of the composition outlet through which air is drawn in respective air jets when suction is applied to the outlet end. The composition and air outlets are arranged such that, in use, the pair of air jets impinge on the composition plume.

Claims

1. An inhaler comprising: a source of inhalable composition; an outlet flow path for the composition from the source to a composition outlet, at an outlet end of the inhaler, means to generate a flow of composition from the source along the outlet flow path and out of the composition outlet when suction is applied to the outlet end; and a pair of air outlets at the outlet end arranged on opposite sides of the composition outlet through which air is drawn in respective air jets when suction is applied to the outlet end, the composition and air outlets being arranged such that, in use, the pair of air jets impinge on the composition plume, wherein the composition outlet and the air outlet being arranged such that the inhalable composition and the air leave the inhaler separately.

2. An inhaler according to claim 1, wherein there are only two air outlets.

3. An inhaler according to claim 1, wherein additional outlets are present in at least one additional opposed pair.

4. An inhaler according to claim 1, wherein the air outlets are angled towards the composition outlet such that the air jets converge towards the composition plume.

5. An inhaler according to claim 1, where the pressure drop across the air outlets as measured with air outlets of 1 mm diameter is 3 kPa-4 kPa.

6. An inhaler according to claim 1, wherein the source of inhalable composition is a pressurised reservoir, and means to generate the flow of the composition is a breath operated valve.

7. An inhaler according to claim 6, wherein the air outlets are associated with one or more air inlets spaced from the outlet end such that there is a through flow path from the air inlets to the air outlets.

8. An inhaler according to claim 6, wherein the pair of air outlets are associated with air flow paths which at least partially operate the breath operated valve.

9. An inhaler according to claim 8, wherein the breath operated valve comprises: a valve element biased by a biasing force into a position in which it closes the outlet flow path for the composition; a flexible diaphragm arranged to move the valve element; a first flow path partly defined by one side of the diaphragm; and a second air flow path partly defined by the opposite side of the diaphragm, each flow path having an opening at the outlet end, wherein the air flow paths are arranged such that suction at the outlet end causes a reduction pressure in the first air flow path and a relative increase in pressure in the second air flow path, creating a pressure differential across the diaphragm that moves the diaphragm and hence moves the valve element against the biasing force to open the outlet flow path for the composition, wherein the pair of air outlets provide the opening at the outlet end of the second air flow path.

10. An inhaler according to claim 1, where upon a standard inhalation, the flow through all of the air outlets in total is 0.5 l/m to 60 l/m.

11. The inhaler according to claim 10, where upon a standard inhalation, the flow through all of the air outlets in total is 1.0 l/m to 5 l/m.

12. The inhaler according to claim 10, where upon a standard inhalation, the flow through all of the air outlets in total is 1.5 l/m.

13. An inhaler according to claim 1, wherein the diameter of an exit of the composition outlet is 0.1 mm to 1 mm and the diameter of each of the pair of outlets is 0.1 mm to 1.2 mm.

14. The inhaler according to claim 13, wherein the diameter of the exit of the composition outlet is 0.2 mm and the diameter of each of the pair of air outlets is 0.4 mm.

15. An inhaler according to claim 1, wherein the ratio of cross-sectional area of an exit of the composition outlet to the total cross-sectional area of air outlets is between 16:1 and 1:1.

16. The inhaler according to claim 15, wherein the ratio of cross-sectional area of the exit of the composition outlet to the total cross-sectional area of air outlets is between 4:1 and 1:1.

17. An inhaler according to claim 1, wherein the total cross sectional exit area of the composition outlet is 0.008 mm.sup.2 to 0.8 mm.sup.2 and the total cross-sectional area of air outlets is from 0.14 mm.sup.2 to 1.0 mm.sup.2 wherein the ratio of the two areas is 2:1 to 8:1, and gives a droplet size of 5 microns as a D50.

18. The inhaler of claim 17 wherein the total cross-sectional exit area of the composition outlet is 0.07 mm.sup.2 to 0.2 mm.sup.2 and gives a droplet size of 0.6 microns.

19. An inhaler according to claim 1, wherein the pressure drop across the air outlets as measured with twin air jets is 0.5-4 kPa.

20. An inhaler according to claim 19, where the pressure drop as measured with twin air jets is 2-4 kPa.

Description

(1) An example of an inhaler in accordance with the present invention will now be described with reference to the accompanying drawings, in which:

(2) FIG. 1 is an exploded perspective view of an inhaler;

(3) FIG. 2 is a schematic axial cross-section through the outlet end of the inhaler in the plane containing an air flow path and with the vane removed for clarity;

(4) FIG. 3 is a perspective view of the outlet end of the inhaler with the cover, vane and diaphragm removed to show the air flow paths;

(5) FIG. 4 is a perspective view of the outlet end of the inhaler;

(6) FIG. 5 is a plan view of the inhaler;

(7) FIG. 6 is a full cross-section of the inhaler;

(8) FIG. 6A is a cross-section through line 6A-6A in FIG. 6; and

(9) FIG. 7 is a Flow Rate Test Rig Schematic.

(10) The present invention relates to an improvement of the outlet valve for an inhaler such as that disclosed in WO 2011/015826. For further details of the device and its refill mechanism, reference is made to WO 2009/001078.

(11) As shown in FIG. 1, the device comprises a housing 1 which is broadly divided into two parts. The distal part is a reservoir 2 and the proximal part is the breath-activated valve mechanism 3. At the distal end 4 is a refill valve 5 allowing the reservoir to be filled. The reservoir may contain a wick 6 as disclosed in PCT/GB2011/000285. At the opposite end is the outlet end 5 which will be described in more detail below.

(12) As best shown in FIG. 6, the reservoir has a portion 8 adjacent to the distal end 4 which occupies substantially the entire cross-section of the inhaler at this point. A second portion 9 which is closer to the outlet end 7 occupies a relatively small portion of the cross-section of the inhaler because, as shown in FIG. 6, this part of the inhaler also accommodates the valve mechanism described below and provides space for the air flow paths also described below.

(13) As can be seen from FIGS. 1 and 3, this second portion 9 of the reservoir is part of the same molding as the housing 1 and runs along the lower part of the inhaler.

(14) An elastomeric insert 10 in the form of a tube open at both ends is inserted from the distal end, but forms an outlet flow path at the proximal end of the inlet path as shown in FIG. 6. This insert 10 is normally pinched closed by a valve element 11 which is biased downwardly by a spring 11. This pinch closed valve mechanism is described in greater detail in WO 2011/315825.

(15) The valve element 11 is part of a vane 13 which extends along most of the outlet end of the inhaler. The vane 13 is surrounded by a diaphragm 14 which extends across the entire lower face of the vane 13, with the exception of the orifice through which the valve element 11 projects. This valve element is sealed around its periphery to the surrounding housing. At the distal end of the diaphragm 14 is a kink 15 which provides some degree of freedom for the vane 13 to move up and down. The vane and its frame are both made of a rigid plastic material while the diaphragm is a clearer flexible material. There is a direct connection between the material of the tongue and the material of the frame such that it is the material of the tongue which is acting as the hinge, rather than the material of the membrane. The opposite end of the vane 13 is integral with a surrounding frame that is filled into the housing such that there is a direct connection between the frame and vane to provide a hinge about which the vane pivots.

(16) A mechanism for opening the valve element 11 against the action of the spring 12 will now be described.

(17) This is achieved by first 16 and second 17 air flow paths. The first flow path 16 is above the diaphragm 14 with the top of the flow path being formed by housing part 18 which is fixed to the housing 1 once the valve elements are in place. The first air flow path is essentially provided by a first air flow path outlet orifice 19 which leads into the space occupied by the vane 13 above the diaphragm 14. This flow path has no other orifices.

(18) The second air flow path 17 is below the diaphragm 14 and is defined by a pair of second air flow path inlet orifices 20 (only one of which is shown in FIG. 2). In the present example, the second air flow path is actually defined by two separate paths which extend from the inlet orifices 20 along passages 17 which are defined by the housing 1 on the lower surface and the diaphragm 11 at its upper surface and which extends alongside the second portion 9 of the reservoir to the outlet end terminating at a pair of second air flow path outlet orifices 21 which are smaller than the corresponding inlet orifices 20. The flow through the second air flow path is depicted by arrows in the lower part of FIG. 2 and in FIG. 3. Baffles 22 are provided along the second air flow path 17 to increase the follow resistance in this path.

(19) As a user sucks on the outlet end 7, air is sucked out of the first flow path outlet orifice 15 thereby lowering the pressure in the first air flow path 16. At the same time, air is drawn in through the second flow path air inlet orifices 20. The combination of a reduced pressure above the vane and the prevention of the significant pressure reduction below the vane causes the vane to be moved upwardly deforming the diaphragm and raising the valve element against the action of the spring 12. When a user stops sucking on the outlet end, the pressure above and below the diaphragm equalises and the spring 12 returns the valve element 11 to a position in which it pinches the insert 10 closed.

(20) As shown in FIGS. 1, 2 and 4, the outlet end 7 at the part containing the insert 10 and the air flow path outlet orifices 21 has a concave configuration 23. As a result of this, the outlet orifices 21 are inclined towards the insert 10. Upon inhalation, the air exiting the outlet orifices 21 is angled towards the plume of composition emerging from the insert 10 such that the air quickly impinges on the composition thereby creating greater turbulence and reducing the mean particle size of the composition.

(21) For traditional tobacco cigarettes, international standards ISO:6565 and ISO 7210 govern the test and methodologies of draw resistance and pressure drop of tobacco cigarettes. This is an important measure for product quality specifications and for matching analytical determinations by mechanical smoking.

(22) FIG. 7 is a general schematic for a test method under these standards and shows a flow rate test rig which enables an assessment of the pressure drop across the inhaler device at different flow rates. The pressure drop is applied using a vacuum pump 30 under the control of a variable restrictor 31 and is measured using a suitable pressure gauge 32, zeroing the pressure gauge before testing to compensate for changes in atmospheric pressure. The flow rate is measured from the top of a float 33 in a flow tube 34. Each inhalation is measured in accordance with ISO 7210:1997.

(23) The size of the air jets influences the draw resistance of the inhalation such that there has found to be a direct correlation with the measured pressure drop across the air outlet orifices under ISO:7210 against the diameter of the second air flow path outlet orifices. For example, with two air such orifices each having a diameter of 0.45 mm, the mean draw resistance tested across 100 devices is 2.8 kPa. When the orifices have a diameter of 0.40 mm they give a mean pressure drop at 3.7 kPa, and when they have a diameter of 0.33 mm they give a mean pressure drop of 5.2 kPa. It is preferable for the invention that a mean pressure drop is in the range between 2 kpa and 4 kpa for the optimum performance characteristics for a smoker on an aerosolised simulated cigarette. This allows a selected tuning of the device to fit particular strength of formulation, for example a higher resistance device will be tailored for a higher strength formulation.

(24) Our co-pending application GB 1215273.2 discloses suitable formulations for the composition. A higher draw resistance device with twin air jets of 0.38 mm in diameter can be paired with a higher strength nicotine formulation for example 0.084 w/w %. This is similar to conventional tobacco cigarettes since higher nicotine content cigarettes correlate with having higher draw resistances. Thus the inhaler can provide a method and a mechanism to tune the pressure drop across the air jet to particular strengths of formulation to deliver expanded product ranges and enhanced consumer acceptance.