Inhaler

Abstract

An inhaler comprising a reservoir of an inhalable composition. A valve element moved by a flexible diaphragm and biased into a position in which it closes a composition flow path from a reservoir. A first air flow path is partly defined by one side of the diaphragm and a second air flow path is partly defined by the opposite side of the diaphragm. Each flow path has an outlet opening at an outlet end and the second flow path has an inlet upstream of the outlet end. The air flow paths are arranged such that suction at the outlet end causes a reduction in pressure in the first air flow path relative to the pressure in the second air flow path creating a pressure differential across the diaphragm that moves the valve element against the biasing force to open the composition flow path.

Claims

1. An inhaler comprising; a reservoir of an inhalable composition; a housing containing the reservoir and having an outlet end; a composition flow path for the flow of the composition from the reservoir and out of a composition outlet at the outlet end of the housing; a valve element biased by a biasing force into a first position in which it closes the composition flow path; a flexible diaphragm arranged to move the valve element; and a first air flow path partly defined by one side of the diaphragm, a second air flow path partly defined by the opposite side of the diaphragm, each flow path having an outlet opening at the outlet end and the second flow path having an inlet upstream of the outlet end, wherein the air flow paths are separate from the composition flow path and are arranged such that suction at the outlet end causes a reduction in pressure in the first air flow path relative to the 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 a second position in which the composition flow path is open, and wherein: cessation of the suction at the outlet end equalizes the pressure differential across the diaphragm, causing the biasing force is configured to return the valve element to the first position in which it closes the composition flow path, the composition flows from the reservoir and out of the composition outlet as long as the suction is continuously applied at the outlet end, and cessation of the suction at the outlet end causes the composition to stop flowing from the reservoir when a user stops sucking on the outlet end of the inhaler.

2. An inhaler as claimed in claim 1, wherein the pressure in the second air flow path remaining substantially at atmospheric when suction is applied to the outlet ends.

3. An inhaler as claimed in claim 1, wherein the second air flow path is configured so that there is no increase in pressure in the second air flow path when suction is applied at the outlet end.

4. An inhaler according to claim 1, wherein the open area of the second air flow path at its inlet is larger than its open area at the outlet end.

5. An inhaler according to claim 1, wherein the first air flow path is closed other than the opening at the outlet end.

6. An inhaler according to claim 1, wherein the composition flow path is on the same side of the diaphragm as the second flow path.

7. An inhaler according to claim 1, wherein baffles are provided in the second air flow path to increase the flow resistance therethrough.

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; and

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

(9) 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.

(10) 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.

(11) 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.

(12) 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.

(13) 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 2011/015825.

(14) 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 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.

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

(16) 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.

(17) 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.

(18) 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 a 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.