A liquid delivery device with a one-way valve

Abstract

A liquid delivery device, such as a nebulizer or soft mist inhaler, comprises a lower housing part 112 configured to contain a collapsible reservoir, and an upper housing part 111 configured to contai

Description

TECHNICAL FIELD The present invention relates to a liquid delivery device with a one-way valve. More particularly, the present invention relates to a nebuliser comprising a nozzle assembly with a one-way valve. Even more particularly, the present invention relates to a drug delivery device comprising a nozzle assembly with a one-way valve. BACKGROUND Drug delivery devices such as nebulisers are used to produce an aerosol of droplets for inhalation through the mouth and pharyngeal cavity into the lungs of a patient, for nasal administration, or for spraying the surface of the eye. In a nebulising drug delivery device such as a soft mist inhaler (SMI), liquid pharmaceutical formulations are typically stored in a reservoir or ‘bag’ formed from a plastic material. From there, they are conveyed through a riser tube into a pressure chamber from where they are forced through a nozzle under pressure and atomised. In this way, drug delivery devices such as SMIs are able to nebulise a small amount of a liquid formulation according to the required dosage within a few seconds, to produce an aerosol suitable for therapeutic inhalation. Moreover, this can be achieved without requiring the use of a propellant. A typical, known, type of SMI or nebuliser device is shown in figure 1. The device has an upper half that contains a nozzle, and a lower half that contains a collapsible reservoir or ‘bag’. A tube extends axially along the device from the nozzle to the reservoir. The upper and lower halves are rotated relative to one another in use to pump or prime the device. As the device is pumped (by rotating the two halves relative to one another), a negative pressure is applied to the bag (suction) to pull liquid from the reservoir into the tube towards the nozzle, and the bag structure is pulled inwards (collapses inwards). For each individual use, the collapse is small, with each use adding incrementally to the overall full collapse of the bag at end-of-life. When the device is subsequently triggered by a user, a nebulised mist of product is delivered through the nozzle at the upper end of the device. However, in devices of this type, even with a bag that has a thin wall, there is an inherent stiffness to overcome, and this increases as the bag empties. The bag is always ‘fighting’ the collapse caused by suction of the contents from the bag. The more resistance to collapse, the more resistance there is to drawing liquid up. As well as this, the nozzle creates an air leakage path from the exterior of the device to the interior. When the device is pumped or primed, liquid from the bag is drawn into and up the tube, but air can be drawn inwards through the nozzle, or by bypassing seals. This impacts on the pressure differential created by pumping / priming the device, and reduces the ability of the device to deliver a consistent or repeatable dose. The air leakage path also provides an open route through the nozzle. Due to the open access to the environment, this can reduce the shelf-life, stability, and protection of the formulation. In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art. SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid delivery device comprising a nozzle assembly with a one-way valve which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice. It is a further object of the present invention to provide a nebuliser comprising a nozzle assembly with a one-way valve which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice. It is a yet still further object of the invention to provide a drug delivery device comprising a nozzle assembly with a one-way valve which goes some way to overcoming the abovementioned disadvantages or which at least provides the public or industry with a useful choice. Accordingly, in a first aspect the present invention may broadly be said to consist in a liquid delivery device, comprising: a lower housing part configured to contain a collapsible reservoir; an upper housing part configured to contain a nozzle assembly, the nozzle assembly configured to convert liquid received at the inner end to a droplet spray at the outer end for delivery to a user; a passage extending between the collapsible reservoir and the nozzle assembly to in use deliver liquid from the collapsible reservoir to the nozzle assembly; a one-way valve located in the passage, the one-way valve configured to open to allow liquid to pass from the collapsible reservoir to the nozzle assembly, the valve in the closed position substantially blocking the passage to prevent the flow of gases and fluids into the collapsible reservoir. In an embodiment, the one-way valve comprises: a main body configured to locate within and extend across the passage so as to hold and stabilise the one-way valve in position within the passage; a blocking member configured to move within the nebuliser passage from a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage; a biasing mechanism configured to extend between the main body and the blocking member to bias the blocking member towards the first position. In an embodiment, the main body is ring-shaped. In an embodiment, the blocking member comprises a ball bearing. In an embodiment, the biasing mechanism comprises a plurality of spring prongs. In an embodiment, the spring progs are spaced at substantially equal intervals from one another. In an embodiment, the biasing mechanism comprises three spring prongs. In an embodiment, the spring prongs are angled inwards. In an embodiment, the blocking member ends of the spring prongs are shaped to receive the blocking member. In an embodiment, the blocking member comprises a flat sealing portion. In an embodiment, the flat sealing portion has a chamfered edge. In an embodiment, the spring mechanism comprises a plurality of spring members integrally formed with and extending from the main body. In an embodiment, the spring members are spaced at substantially equal intervals from one another. In an embodiment, the biasing mechanism comprises three members. In an embodiment, the flat sealing portion and spring mechanism are integrally formed with the main body so that the one-way valve is a unitary item. In an embodiment, the one-way valve comprises a duck-bill valve. In an embodiment, the one-way valve comprises a flap valve. In an embodiment, the one-way valve comprises: a blocking head configured to locate within the nebuliser passage so as to be movable between a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage; a plurality of spring legs configured to locate within and extend across the passage so as to hold and stabilise the one-way valve in position within the passage, and to bias the blocking member towards the first position. In an embodiment, the blocking head is dome-shaped. In an embodiment, the blocking head has a conical shape. In an embodiment, the blocking head is bullet-shaped. In an embodiment, the spring legs have to form of castellations extending from the bottom side of the blocking head. In an embodiment, the spring legs are angled away from one another. In an embodiment, the spring legs are spaced at substantially equal intervals from one another. In an embodiment, the one-way valve comprises four spring legs. In an embodiment, the outer or free ends of the legs are wider than the inner portion of the legs. In an embodiment, the spring legs have a curved outer profile so that the curve of the legs conforms to the cross-sectional shape of the recess. In an embodiment, the blocking head has a diameter of substantially 2.5mm. In a second aspect the present invention may broadly be said to consist in a one-way valve for a liquid delivery device, comprising: a main body configured to locate within a passage within the liquid delivery device; a blocking member configured to move within the passage from a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage; a biasing mechanism configured to extend between the main body and the blocking member to bias the blocking member towards the first position. In an embodiment, the main body is ring-shaped. In an embodiment, the blocking member comprises a ball bearing. In an embodiment, the biasing mechanism comprises a plurality of spring prongs. In an embodiment, the spring prongs are angled inwards. In an embodiment, the blocking member ends of the spring prongs are shaped to receive the blocking member. In an embodiment, the blocking member comprises a flat sealing portion. In an embodiment, the flat sealing portion has a chamfered edge. In an embodiment, the spring mechanism comprises a plurality of spring members integrally formed with and extending from the main body. In an embodiment, the flat sealing portion and spring mechanism are integrally formed with the main body so that the one-way valve is a unitary item. In a third aspect the present invention may broadly be said to consist in a one-way valve for a liquid delivery device, comprising: a blocking head configured to locate within a passage within the liquid delivery device so as to be movable between a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage; a plurality of spring legs configured to locate within and extend across the passage so as to hold and stabilise the one-way valve in position within the passage, and to bias the blocking member towards the first position. In an embodiment, the blocking head is dome-shaped. In an embodiment, the blocking head has a conical shape. In an embodiment, the blocking head is bullet-shaped. In an embodiment, the spring legs have to form of castellations extending from the bottom side of the blocking head. In an embodiment, the spring legs are angled away from one another. In an embodiment, the spring legs are spaced at substantially equal intervals from one another. In an embodiment, the one-way valve comprises four spring legs. In an embodiment, the outer or free ends of the legs are wider than the inner portion of the legs. In an embodiment, the spring legs have a curved outer profile so that the curve of the legs conforms to the cross-sectional shape of the recess. In an embodiment, the blocking head has a diameter of substantially 2.5mm.This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a side view of a known, prior art type of manually-operated nebuliser that has an upper half and a lower half, the two halves rotated relative to one another in use to pump or prime the device for use. Figure 2 shows a top perspective view of a known, prior art nebuliser similar to that of figure 1, showing detail of a nozzle assembly located in the upper half. Figure 3 shows a side schematic view of a nozzle assembly, showing general detail of the main parts of a nozzle assembly and their relative locations and connections. Figure 4 shows a perspective side view of a liquid delivery device that in this form is a nebuliser device according to an embodiment of the present invention. Figure 5 shows a perspective cutaway side view of the nebuliser device of figure 4 from the same angle, showing interior detail of the device, including the tube, nozzle, and one-way valve, the bag not shown. Figure 6 shows a perspective close-up detail cutaway side view of the top end of the nebuliser device of figures 4 and 5, from the same angle as figures 4 and 5, showing detail of the nozzle assembly, the nozzle assembly comprising a nozzle retainer, a nozzle seal, a nozzle chip, a filter and filter holder, and a lower seal, all enclosed within a top nut that screws onto the upper end of an upper tube housing located within the upper housing, a tube shown extending through the upper tube housing, a one-way valve according to an embodiment of the invention located below the nozzle holder. Figure 7 shows a perspective close-up detail cutaway side view of the nozzle assembly of the nebuliser device of figures 4, 5, and 6, from the same angle. Figure 8 shows a perspective close-up detail cutaway side view of the nozzle assembly of the nebuliser device of figure 7, showing further detail of the one way valve, the one way valve comprising a ball bearing and a crown spring. Figure 9a shows a close-up side view of the nozzle assembly of figures 4 to 8, showing further detail of the ball bearing and crown spring of the one-way valve. Figure 9b shows a perspective close-up detail cutaway side view of a variation of the nozzle assembly of figures 4 to 8, showing detail of a seal located between the ball bearing and the upper tube housing. Figure 10 shows a perspective side view of the crown spring of the embodiment of one-way valve of figures 4 to 9, the crown spring comprising a circular or ring-shaped base and three spring prongs extending from one side of the base. Figure 11 shows a perspective side view of the crown spring of figure 11 from another angle. Figure 12 shows a perspective side view of the crown spring of figures 10 and 11. Figure 13 shows a perspective cutaway side view of a nebuliser device nozzle assembly that contains a second embodiment of one-way valve, the nebuliser having a substantially similar structure to that of the nebuliser of figures 4 to 8, the second embodiment of one-way valve positioned in substantially the same location. Figure 14 shows a close up perspective cutaway side view from substantially the same angle of figure 13, showing detail of the one-way valve of this embodiment Figure 15 shows a perspective cutaway side view of a nebuliser device nozzle assembly that contains a third embodiment of one-way valve, the nebuliser having a substantially similar structure to that of the nebuliser of figures 4 to 8, the one-way valve positioned in substantially the same location, the valve in this embodiment comprising a flat valve. Figure 16 shows a close up cutaway perspective side view of the nebuliser device nozzle assembly from a similar angle to figure 15. Figure 17 shows a perspective side view of the third embodiment of one-way valve, the valve in this embodiment comprising a flat valve, the flat valve comprising a flat sealing portion connected to a valve base by three spring members that act to bias the flat sealing portion into a closed position. Figure 18 shows a perspective side view of the third embodiment of one-way valve from a different angle. Figure 19 shows a perspective end view of the third embodiment of one-way valve. Figure 20 shows a cutaway perspective side view of a nebuliser device nozzle assembly that contains a fourth embodiment of one-way valve, the nebuliser having a substantially similar structure to that of the nebuliser of figures 4 to 8, the one-way valve positioned in substantially the same location, the one-way valve in this embodiment comprising a flap valve. Figure 21 shows a perspective view of the flap valve of the fourth embodiment of one-way valve as shown in figure 20. Figure 22 shows a perspective cutaway side view of a nebuliser device nozzle assembly that contains a fifth embodiment of one-way valve, the nebuliser having a substantially similar structure to that of the nebuliser of figures 4 to 8, the one-way valve positioned in substantially the same location, the one-way valve comprising a bullet valve. Figure 23 shows a close-up view of the nozzle assembly of figure 22 from the same angle Figure 24 shows a perspective side view of the bullet valve of the fifth embodiment. DETAILED DESCRIPTION Detailed embodiments of the invention will now be described with reference to the figures. General The one-way valve of the present invention is described below as being used as part of a liquid delivery device that is a nebuliser device, a version of which - nebuliser 1000 - is shown in figures 4 and 5 for the first embodiment of one-way valve (detail of the first embodiment shown in figures 5 to 12). Substantially similar nebuliser devices are used for the second, third, fourth, and fifth embodiments as shown in figures 13 and 14, figures 15 to 19, figures 20 and 21, and figures 22 to 24 respectively. Similar numbering will be used to refer to similar elements on all the devices as described below - e.g. nebuliser device 100, 200, 300, upper housing part 101, 201,301, one-way valve 140, 240, 340 etc, for the first, second and third embodiments respectively. General numbering is used in this section for the general form of nebuliser device, a schematic version of which is shown in figure 3. The general or stylised form of nozzle assembly 13 and other relevant parts are shown in figure 3 for the purposes of illustration of the general structure. A general form of nebuliser device is shown in figure 4. The general form of nebuliser comprises an upper housing half (generally designated as 11, but designated as 111,211, etc for specific embodiments) that contains a nozzle assembly 13, and a lower housing half (generally designated as 12, but designated as 112, 212, etc) that in use contains a collapsible reservoir or ‘bag’ (not shown in the figures). A capillary tube 14 extends between the bag and the nozzle assembly 13. The nozzle assembly 13 comprises: a nozzle retainer 15; a nozzle chip 16; a nozzle seal 22; a filter holder 21 and filter 20; a lower seal 17, and; a top nut 18. The nozzle holder 15, nozzle chip 16, lower seal 17, top nut 18, filter 20, filter holder 21, and nozzle seal 22 are all enclosed within the top nut 18. In use, the top nut 18 screws onto the upper end of an upper tube housing 19 that is located within the upper housing part 11. The upper tube housing 19 has a passage 23 passing substantially axially therethrough, with a capillary tube 14 passing most of the way through the passage 23 from the base or lower end (that end that is towards the bag), to the upper end where the nozzle assembly 13 is located. The space between the upper end of the capillary tube 14 and the lower end of the nozzle assembly 13 forms a metering chamber. The one-way valve of the present invention is located in the top end of the passage between the lower end of the nozzle assembly 13 and the top end of the capillary tube 14, above the space the forms the metering chamber. For the purposes of this specification, the ‘passage’ should be considered to run between the lower end of the structure within the bag, and the lower end of the nozzle assembly 13. In use, the capillary tube 14 moves within the passage towards and away from the nozzle assembly 13 as the nebuliser device is used. That is, vertically upwards and downwards in the orientation shown in figure 3, which is the orientation for a nebuliser standing upright on a horizontal surface such as a table top. References to orientations such as ‘upwards, ‘downwards’ and similar should be taken in this specification as meaning this orientation (i.e. the nebuliser stood upright), even if in use the orientation would differ from this. In use, a user rotates the upper and lower parts 11,12 relative to one another to pump or prime the device for use. This action causes the capillary tube 14 and bag to move away from the nozzle assembly 13 (that is, downwards towards the base of the nebuliser if it is aligned upright in a similar manner to the prior art nebuliser shown in figure 1). Liquid from the bag is sucked up the tube 14 to the upper end, and into the metering chamber. This action also tensions a spring 35 within the nebuliser. When a user then triggers the dispensing mechanism (e.g. by pressing a button or similar on the housing of the nebuliser), the tube 14 is forced upwards by the release of tension in the spring 35, and the head of the tube 14 moves rapidly upwards, forcing liquid out of the metering chamber through the nozzle assembly 13, as a spray of fine droplets. It should be noted that the one-way valve of the embodiments described below helps to increase the efficiency of the suction or vacuum operation where liquid from the bag is sucked up the tube. The presence of the one-way valve helps to increase the pressure difference between the interior and exterior of the bag, by not allowing air to be sucked into the bag. One-Way Valve - First Embodiment As shown in figures 5 to 9, the one-way valve 140 of the first embodiment comprises a ball bearing 130 and a crown spring 131. These are located in a recess formed at the upper end of the passage 123, between the head of the capillary tube 114 and the base or inner end of the nozzle assembly 113. The recess is formed so as to be wider than main part of the passage 123, so that a lip 132 is formed between the recess and the main part of the passage 123. The ball bearing 130 is spherical, and has a diameter in the preferred embodiment of 2.5mm. Other diameters can also be used if required - e.g. 2.38mm, 2mm. As best shown with reference to figure 9a, in a first variation of this embodiment, the inner side of the ball bearing rests against the lip 132. The lip 132 can be shaped so as to conform to the outer surface shape of the ball bearing 130, so as to increase the contact area between the ball bearing 130 and the inner surface of the upper tube housing 119 (the lip 132). The ball bearing forms a blocking member for the one-way valve. As best shown in figures 10 to 12, the crown spring 131 comprises a ring-shaped base 131a, and three spring prongs 131b extending from one or the same side of the base 131 a. The ringshaped base forms a main body for the one-way valve, and has a diameter substantially the same as that of the ball bearing 130, which is also substantially the same as that of the recess. The spring prongs 131b are substantially identical to one another, and are spaced at equal distances around the ring of the ring-shaped base 131a - that is, at 120-degree intervals around the ring. The main body acts to hold and stabilise the one-way valve in position within a passage in a liquid delivery device. Each of the spring prongs 131 b is angled inwards slightly so that at their upper ends (that is, the end that in use points downwards or inwards towards the base or bag), the diameter of a circle that covers or connects between the upper ends or tips of the prongs 131b is slightly less than the outer diameter of the ring. The spring prongs act as a biasing member for the one-way valve. The outer side of the ball bearing 130 rests on the upper ends of the spring prongs 131 b. These upper ends can be shaped so as to receive the ball bearing - that is, to increase the contact area between the two. The outer or upper side of the ring-shaped base 131 a rests against the inner or lower end of the filter holder 121. In use, a user rotates the upper and lower parts 111, 112 relative to one another to pump or prime the device for use as described above for the general form of inhaler, This causes a pressure drop in the metering chamber section of the passage, between the upper end of the capillary tube, and the lower end of the ball bearing 132 (the volume of the space increases, while the same amount of fluid / gas is present). As the pressure on the upper side of the ball bearing 132 doesn’t change, this causes a pressure gradient that pushes the ball bearing 130 onto the lip 132, which helps to increase the quality of the seal between the passage 123 and the upper end of the device, at the other / upper side of the ball bearing 130. As outlined above, as the capillary tube 114 moves downwards, liquid in the bag is drawn up the capillary tube 114 into the space between the top end of the capillary tube and the inner side of the ball bearing - the metering chamber. This re-sets or substantially equalises the pressure in the chamber. When a user triggers the nebuliser, this dose of liquid is forced past the ball bearing 130, through the filter 120 and the nozzle chip 116, and out through the nozzle for delivery to a user. This is because the priming action of rotating the two housing halves also causes compression or tension of spring 135. When a user triggers the nebuliser, the spring 135 forces the capillary tube 114 upwards at speed, rapidly increasing the pressure in the metering chamber space. This pressure forces the ball bearing 130 upwards / outwards against the spring prongs 131b, which bend towards the sides of the recess and allow the ball bearing to move upwards / outwards (it can be seen that the travel distance of the ball bearing 130 will be limited by the arms - these will contact the side wall of the recess so that further bending is not possible, and therefore further movement of the ball bearing against the spring action of the prongs 131b is prevented). As the ball bearing has now moved away from the lip 132, the liquid in the metering chamber can now move upwards past the ball bearing, and on through the filter assembly and out of the nebuliser. This action has the further advantage that a certain minimum level of pressure is required in order to initiate movement of the ball bearing 130 against the spring prongs 131b. The valve is pressed closed - the spring prongs 131 b press the ball bearing 130 against the lip 132 - and a certain minimum level of pressure needs to be applied to the underside of the ball bearing in order to overcome the spring force of the spring prongs 131b and cause the ball bearing to move upwards, away from the lip 132. This helps to overcome the ‘start-up effect’ of certain previous forms of nebulisers where pressure builds up gradually initially. This gradual building of pressure tends to have the effect in use that larger droplets are formed initially, until the pressure reaches full operational force. At full operational force the pressure then provides small and even-size droplets. The arrangement of this embodiment, with the valve held closed until a threshold pressure is reached, helps to provide a quicker Tamp up phase’, and therefore a more consistent droplet size. This is useful for delivery of lower volumes of medication - ramp up and tail effects are less pronounced and therefore have a smaller impact. In a variation of this embodiment as shown in figure 9b, a seal 117b is located within the inhaler, so that in use this is between the ball bearing 130 and the upper tube housing 119. In use, the ball bearing 130 is pressed onto the upper surface of the seal 117b by the crown spring 131. It should be noted that this seal could be of any suitable shape and size, as long as it locates in use between the one-way valve and the upper tube housing. This arrangement - that is, including a seal - can also be used in the other embodiments as appropriate. One-Way Valve - Second Embodiment As shown in figures 13 and 14, the one-way valve of the second embodiment comprises a duckbill valve 240. The duck-bill valve is located at / above the top of passage 223, between the head of the capillary tube 214 and the base or inner end of the nozzle assembly 213. The duckbill valve has a base 240a, and a valve section 240b. The lower or inner side of the base 240a rests on the top surface of the upper tube housing 219 to form a seal. A recess 250 is formed in the base 240a. The valve section 240b extends upwards from the base 240a with the wider end at the base. The duck-bill valve allows fluid / gases to flow through the valve in one direction (upwards / outwards), but substantially prevents gas / fluid flow through the valve in the other direction. In use, a user rotates the upper part 211 and the lower part (not shown) relative to one another to pump or prime the device for use as for the first embodiment. The capillary tube 214 moves downwards, away from the nozzle assembly 213 and into the bag, causing a pressure drop in the metering chamber section of the passage, between the upper end of the capillary tube, and the interior portion of the duck-bill valve 240. The valve is closed during this operation, so as to prevent flow through the valve, and so as the capillary tube moves, the volume of the space increases while the same amount of fluid / gas is present. Figure 13 shows the capillary tube 214 moved at least partly downwards into or towards the ‘primed’ position. As the capillary tube 214 moves downwards, liquid in the bag is drawn up the capillary tube 214 into the space between the top end of the capillary tube, and the top end of the passage 223 and the interior of the valve, equalising the pressure. When a user triggers the nebuliser, this dose of liquid is forced upwards as the pressure in the metering chamber increases, which forces the valve to open so that the liquid is forced through the valve 240, through the filter 220 and the nozzle chip 216, and out through the nozzle for delivery to a user. This is because the priming action of rotating the two housing halves also causes compression of a spring. When a user triggers the nebuliser, the spring forces the capillary tube 214 upwards at speed, rapidly increasing the pressure in the metering chamber space and forcing the valve portion 240b or the valve 240 open, allowing the liquid in the metering chamber to move upwards through the valve, and on through the filter assembly and out of the nebuliser. The capillary tube 214 is shown in the upwards or ‘triggered’ position in figure 14. One-Way Valve - Third Embodiment As shown in figures 15 to 19, the one-way valve of the third embodiment comprises a flat valve 340. The flat valve 340 is located at / above the top of passage 323, between the head of the capillary tube 214 and the base or inner end of the nozzle assembly 313. The flat valve comprises a flat sealing portion 340a, a ring-shaped main body 340b, and three curved spring members 340c that connect between the sealing portion 340a and the main body 340b, the three curved spring members 340c acting in use to bias the flat sealing portion 340a into a closed position. That is, they act as a biasing mechanism for the one-way valve. As shown in figures 15 and 16, a recess is formed in the top end of the upper tube housing 319. The ring-shaped main body 340b locates into the recess in use, extending the full height of the recess, contacting the side wall of the recess around the perimeter of the side wall of the recess. The main body acts to hold and stabilise the one-way valve in position within a passage in a liquid delivery device. The three curved spring members 340c extend inwards and downwards from the top end of the main body 340b, to the sealing portion 340a. The sealing portion 340a locates over the top end of the passage 323 to seal the passage 323 -that is, to act as a blocking member. In this embodiment, the inner / lower side edge of the sealing portion 340a and the top end of the passage 323 are mutually chamfered to increase the contact surface area and therefore the effectiveness of the seal. The top of the passage forms a lip 332. As for the previously-described embodiments, in use a user rotates the upper and lower parts of the nebuliser within which the third embodiment of one-way valve is fitted relative to one another to pump or prime the device. This causes a pressure drop in the metering chamber section of the passage, between the upper end of the capillary tube, and the lower / inner side of the sealing portion 340a. The sealing portion 340a seals against the top end of the passage to prevent flow from the upper end of the nebuliser into the passage 323, and so as the capillary tube moves the volume of the space increases while the same amount of fluid / gas is present, causing a pressure drop that acts to ‘suck’ the sealing portion 340a onto the top end of the passage. As the capillary tube 314 moves downwards, liquid in the bag is drawn up the capillary tube 314 into the space between the top end of the capillary tube, and the top end of the passage 323 and the interior of the valve, equalising the pressure. When a user triggers the nebuliser, this dose of liquid is forced through the valve 340, through the filter 320 and the nozzle chip 316, and out through the nozzle for delivery to a user. This is because the priming action of rotating the two housing halves also causes compression of a spring. When a user triggers the nebuliser, the spring forces the capillary tube 314 upwards at speed, rapidly increasing the pressure in the metering chamber space and forcing the sealing portion 340a upwards to open - that is, the pressure caused by movement of the capillary tube 314 is sufficient to overcome the force exerted by the three curved spring members 340c. This allows the liquid in the metering chamber to move upwards through the valve, and on through the filter assembly and out of the nebuliser. One-Way Valve - Fourth Embodiment As shown in figures 20 and 21, the one-way valve of the fourth embodiment comprises a flap valve 440. The flap valve 440 is located at / above the top of passage 423, between the head of the capillary tube 414 and the base or inner end of the nozzle assembly. As shown in figure 21, the flap valve 440 is planar, and comprises a flat sealing portion 440a, a ring-shaped main body 440b, and two connecting members 440c that connect between the sealing portion 440a and the main body 440b. The main body acts to hold and stabilise the one-way valve in position within a passage in a liquid delivery device. The planar nature of the flap valve 440 means that the connecting members 440c act in use to bias the flat sealing portion 440a towards the plane of the flap valve. In use, the flap valve 440 is located within the housing so that it is planer when no ‘usage’ forces are acting on the valve. The sealing portion 440a is located so that the sealing portion extends across the top of the passage 423, to seal the passage. As for the previously-described embodiments, in use a user rotates the upper and lower parts relative to one another to pump or prime the device. This causes a pressure drop in the metering chamber section of the passage, between the upper end of the capillary tube, and the lower / inner side of the sealing portion 440a. The sealing portion 440a is pulled or ‘sucked’ against the top of the passage by the vacuum of the pressure drop, so as to prevent flow from the upper end of the nebuliser into the passage 423, which helps to increase the efficiency of the seal. As the capillary tube 414 moves downwards, liquid in the bag is drawn up the capillary tube 414 into the space between the top end of the capillary tube, and the top end of the passage 423 and the interior of the valve, equalising the pressure. When a user triggers the nebuliser, this dose of liquid is forced through the valve 440, the sealing portion 440a moving upwards with the connecting members 440c bending to allow this -that is, the pressure caused by upwards movement of the capillary tube 414 is sufficient to temporarily overcome the spring force holding the seal in a planar configuration. This allows the liquid in the metering chamber to move upwards through the valve, and on through the filter assembly and out of the nebuliser. One-Way Valve - Fifth Embodiment As shown in figures 22 to 24, the one-way valve of the fifth embodiment comprises a bullet valve 540. As shown in the figures, the bullet valve is in use located in a recess formed in the passage 523, at the upper end of the passage, between the head of the capillary tube 514 and the base or inner end of the nozzle assembly 513. The recess is formed so as to be wider than main part of the passage 523, so that a lip 532 is formed between the recess and the main part of the passage 523. The bullet valve 540 is a unitary item that comprises a dome-shaped or hemispherical blocking head 530 and spring legs 531 that have the form of castellations extending from the flat or bottom side of the blocking head 530. The legs 531 in this embodiment from both the main body and biasing mechanism of the one-way valve. The bullet valve is formed from a suitable plastic material such as for example a relatively hard and dense silicone rubber and acts as a blocking member for the one-way valve. The blocking head 530 forms a blocking member, and has a diameter in the preferred embodiment of 2.5mm. Other diameters can also be used if required - e.g. 2.38mm, 2mm. The spring legs 531 are angled slightly outwards from one another so that they ‘spread’ away from one another as they extend from the bottom or flat side of the blocking head 530 (that side that faces ‘upwards’). The outer ends of the legs - that end away from the flat or bottom side of the blocking head 530 - are wider at substantially the last outer third of the leg than the inner two-thirds between the flat or bottom side of the blocking head 530 and the wider leg outer end, with a step formed on the outside of the leg between the last outer third of the leg and the inner two-thirds. In use, the domed or curved side of the blocking head 530 rests against the lip 532. The lip 532 can be shaped so as to conform to the outer surface shape of the blocking head 530, so as to increase the contact area between the blocking head 530 and the inner surface of the upper tube housing 519 (the lip 532). It should be noted that the blocking head could be profiled as an y other suitable shape other than domed - for example, the blocking head could be a conical shape, or bullet-shaped. As shown in figure 24, the spring legs 531 have a curved outer profile that curves in the same direction as the perimeter of the flat side of the blocking head 530, so that the curve(s) of the legs conform to the circular cross-sectional shape of the recess, with the legs fitting snugly within the recess with the outer curved profile resting against the edge / end of the recess so that in use, the outer or free ends of the legs 531 are in effect anchored against the inner or lower end of the filter holder 521. In use, a user rotates the upper and lower parts of the inhaler device relative to one another to pump or prime the device for use as described above for the general form of inhaler, and for the previous embodiments. This causes a pressure drop in the metering chamber section of the passage, between the upper end of the capillary tube, and the lower or outer end of the blocking head 530 (the volume of the space increases, while the same amount of fluid / gas is present). As the pressure on the upper side of the blocking head 530 doesn’t change, this causes a pressure gradient that pushes the blocking head 530 onto the lip 532, which helps to increase the quality of the seal between the passage 523 and the upper end of the device, at the other / upper side of the blocking head 530. In the same or similar manner to that outlined above, as the capillary tube 514 moves downwards, liquid in the bag is drawn up the capillary tube 514 into the space between the top end of the capillary tube and the blocking head 530 - the metering chamber. This re-sets or substantially equalises the pressure in the chamber. When a user triggers the inhaler device, this dose of liquid is forced past the blocking head 530, through the filter 520 and the nozzle chip 516, and out through the nozzle for delivery to a user. This is because the priming action of rotating the two housing halves also causes compression of a spring. When a user triggers the nebuliser, the spring forces the capillary tube 514 upwards at speed, rapidly increasing the pressure in the metering chamber space. This pressure forces the blocking head 530 upwards / outwards against the legs 531. As noted above, the free ends of the legs 531 are anchored against the inner or lower end of the filter holder 521. Both the legs 531 and the blocking head 530 will deform and compress to allow the blocking head 530 to move upwards / outwards. As the blocking head 530 has now moved away from the lip 532, the liquid in the metering chamber can now move upwards past the blocking head, and on through the filter assembly and out of the nebuliser. This action has the further advantage that a certain minimum level of pressure is required in order to initiate movement of the blocking head 530. The valve is pressed closed by the elastic nature of the legs 531 pressing the blocking head 530 against the lip 532, and a certain minimum level of pressure needs to be applied to the underside of the blocking head 530 in order to overcome the spring force of the legs 531 and cause the blocking head 530 to move upwards away from the lip 532. This helps to overcome the ‘start-up effect’ of certain previous forms of nebulisers where pressure builds up gradually initially. This gradual building of pressure tends to have the effect in use that larger droplets are formed initially, until the pressure reaches full operational force. At full operational force the pressure then provides small and even-size droplets. The arrangement of this embodiment, with the valve held closed until a threshold pressure is reached, helps to provide a quicker Tamp up phase’, and therefore a more consistent droplet size. This is useful for delivery of lower volumes of medication - ramp up and tail effects are less pronounced and therefore have a smaller impact. In the embodiments above, the one-way valves are described as being used with a SMI that uses a bag as a medicament reservoir. It should be noted that other types of device, with other types of reservoir, could also be used, such as for example a syringe style cartridge. The use of a one-way valve as in the embodiments described above for the present invention helps to ensure that a correct dosage is administered each time the device is used, and that substantially all or most of the medicament in the reservoir can be used. The use of a seal allows cartridge pre-insertion into the device, as the valve helps to ensure that wicking of liquid formulations within the cartridge will be prevented. The use of a one-way valve also helps to shut off the open route to the air, thus preventing air ingress through that route during priming, but also during storage / at rest. It also prevents / reduces seepage of liquid out through the nozzle when not in use / storage.

Claims

1. A liquid delivery device, comprising:a lower housing part configured to contain a collapsible reservoir;an upper housing part configured to contain a nozzle assembly, the nozzle assembly configured to convert liquid received at the inner end to a droplet spray at the outer end for delivery to a user;a passage extending between the collapsible reservoir and the nozzle assembly to in use deliver liquid from the collapsible reservoir to the nozzle assembly;a one-way valve located in the passage, the one-way valve configured to open to allow liquid to pass from the collapsible reservoir to the nozzle assembly, the valve in the closed position substantially blocking the passage to prevent the flow of gases and fluids into the collapsible reservoir.

2. A liquid delivery device as claimed in claim 1 wherein the one-way valve comprises:a main body configured to locate within and extend across the passage so as to hold and stabilise the one-way valve in position within the passage;a blocking member configured to move within the nebuliser passage from a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage;a biasing mechanism configured to extend between the main body and the blocking member to bias the blocking member towards the first position.

3. A liquid delivery device as claimed in claim 1 or claim 2 wherein the main body is ringshaped.

4. A liquid delivery device as claimed in any one of claims 1 to 3 wherein the blocking member comprises a ball bearing.

5. A liquid delivery device as claimed in any one of claims 1 to 4 wherein the biasing mechanism comprises a plurality of spring prongs.

6. A liquid delivery device as claimed in claim 5 wherein the spring progs are spaced at substantially equal intervals from one another.

7. A liquid delivery device as claimed in claim 5 or claim 6 wherein the biasing mechanism comprises three spring prongs.

8. A liquid delivery device as claimed in any one of claims 5 to 7 wherein the spring prongs are angled inwards.

9. A liquid delivery device as claimed in any one of claims 5 to 8 wherein the blocking member ends of the spring prongs are shaped to receive the blocking member.

10. A liquid delivery device as claimed in claim 2 or claim 3 wherein the blocking member comprises a flat sealing portion.

11. A liquid delivery device as claimed in claim 10 wherein the flat sealing portion has a chamfered edge.

12. A liquid delivery device as claimed in claim 10 or claim 11 wherein the spring mechanism comprises a plurality of spring members integrally formed with and extending from the main body.

13. A liquid delivery device as claimed in claim 12 wherein the spring members are spaced at substantially equal intervals from one another.

14. A liquid delivery device as claimed in claim 12 or claim 13 wherein the biasing mechanism comprises three members.

15. A liquid delivery device as claimed in any one of claims 10 to 14 wherein the flat sealing portion and spring mechanism are integrally formed with the main body so that the one-way valve is a unitary item.

16. A liquid delivery device as claimed in claim 1 wherein the one-way valve comprises a duckbill valve.

17. A liquid delivery device as claimed in claim 1 wherein the one-way valve comprises a flap valve.

18. A liquid delivery device as claimed in claim 1 wherein the one-way valve comprises:a blocking head configured to locate within the nebuliser passage so as to be movable between a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage;a plurality of spring legs configured to locate within and extend across the passage so as to hold and stabilise the one-way valve in position within the passage, and to bias the blocking member towards the first position.

19. A one-way valve for a liquid delivery device as claimed in claim 18 wherein the blocking head is dome-shaped.

20. A one-way valve for a liquid delivery device as claimed in claim 18 wherein the blocking head has a conical shape.

21. A one-way valve for a liquid delivery device as claimed in claim 18 wherein the blocking head is bullet-shaped.

22. A liquid delivery device as claimed in any one of claims 18 to 21 wherein the spring legs have to form of castellations extending from the bottom side of the blocking head.

23. A liquid delivery device as claimed in any one of claims 18 to 22 wherein the spring legs are angled away from one another.

24. A liquid delivery device as claimed in any one of claims 18 to 23 wherein the spring legs are spaced at substantially equal intervals from one another.

25. A liquid delivery device as claimed in any one of claims 18 to 24 wherein the one-way valve comprises four spring legs.

26. A liquid delivery device as claimed in any one of claims 18 to 25 wherein the outer or free ends of the legs are wider than the inner portion of the legs.

27. A liquid delivery device as claimed in any one of claims 18 to 26 wherein the spring legs have a curved outer profile so that the curve of the legs conforms to the cross-sectional shape of the recess.

28. A liquid delivery device as claimed in any one of claims 18 to 27 wherein the blocking head has a diameter of substantially 2.5mm.

29. A one-way valve for a liquid delivery device, comprising:a main body configured to locate within a passage within the liquid delivery device;a blocking member configured to move within the passage from a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage;a biasing mechanism configured to extend between the main body and the blocking member to bias the blocking member towards the first position.

30. A one-way valve as claimed in claim 29 wherein the main body is ring-shaped.

31. A one-way valve as claimed in claim 29 or claim 30 wherein the blocking member comprises a ball bearing.

32. A one-way valve as claimed in any one of claims 29 to 31 wherein the biasing mechanism comprises a plurality of spring prongs.

33. A one-way valve as claimed in claim 32 wherein the spring prongs are angled inwards.

34. A one-way valve as claimed in claim 32 or claim 33 wherein the blocking member ends of the spring prongs are shaped to receive the blocking member.

35. A liquid delivery device as claimed in claim 34 wherein the blocking member comprises a flat sealing portion.

36. A one-way valve as claimed in claim 35 wherein the flat sealing portion has a chamfered edge.

37. A one-way valve as claimed in claim 35 or claim 36 wherein the spring mechanism comprises a plurality of spring members integrally formed with and extending from the main body.

38. A one-way valve as claimed in any one of claims 35 to 37 wherein the flat sealing portion and spring mechanism are integrally formed with the main body so that the one-way valve is a unitary item.

39. A one-way valve for a liquid delivery device, comprising:a blocking head configured to locate within a passage within the liquid delivery device so as to be movable between a first position where fluid flow through the passage is substantially blocked, and a second position where fluid can flow through the passage;a plurality of spring legs configured to locate within and extend across the passage so as to hold and stabilise the one-way valve in position within the passage, and to bias the blocking member towards the first position.

40. A one-way valve for a liquid delivery device as claimed in claim 39 wherein the blocking head is dome-shaped.

41. A one-way valve for a liquid delivery device as claimed in claim 39 wherein the blocking head has a conical shape.

42. A one-way valve for a liquid delivery device as claimed in claim 39 wherein the blocking head is bullet-shaped.

43. A liquid delivery device as claimed in any one of claims 39 to 42 wherein the spring legs have to form of castellations extending from the bottom side of the blocking head.

44. A liquid delivery device as claimed in any one of claims 39 to 43 wherein the spring legs are angled away from one another.

45. A liquid delivery device as claimed in any one of claims 39 to 44 wherein the spring legs are spaced at substantially equal intervals from one another.

46. A liquid delivery device as claimed in any one of claims 39 to 45 wherein the one-way valve comprises four spring legs.

47. A liquid delivery device as claimed in any one of claims 39 to 46 wherein the outer or free ends of the legs are wider than the inner portion of the legs.

48. A liquid delivery device as claimed in any one of claims 39 to 47 wherein the spring legs have a curved outer profile so that the curve of the legs conforms to the cross-sectional shape of the recess.

49. A liquid delivery device as claimed in any one of claims 39 to 48 wherein the blocking head 5 has a diameter of substantially 2.5mm.

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