TITLE
Powder dispensers
DESCRIPTION
Field of the invention
The invention relates to dispensers for releasing powder that is supplied in a sealed capsule. By applying a compressive force to the dispenser, the capsule is pierced and a flow of air is generated through it to entrain the powder from the capsule for delivery to a desired location.
In a typical application, the powder is a medical preparation supplied in capsules and the needles form part of an inhaler device. However, the invention is not limited to medical uses: it could find application in any situation where it is desired to introduce a defined quantity of a powdered substance into a stream of air or other gases.
Background of the invention
There are different routes for administering medications to the human body, including by inhalation into the oral or nasal cavity. Medications are typically administered in these ways for treating topical and/or systemic conditions, including brain and respiratory diseases. Moreover, the nasal cavity could also be useful for mucosal vaccination against infectious diseases. Medications may also enter the bloodstream via membranes in the nasal cavity for the treatment of a range of other conditions, or directly target the olfactory region for more direct nose to brain delivery.
Inhalers are well known medical devices for delivering medications in this way. They may be designed for application to the user's nose or mouth. The medical preparation may be supplied in powder form or may be a liquid that is converted into an aerosol when the inhaler is operated. In some devices, the flow of air needed to entrain the medication is generated purely by the user inhaling strongly. Other devices include a supply of pre-pressurized air or a pump or piston for generating the required airflow.
Some inhalers are disposable in the sense that they are supplied containing one or more capsules and, when those capsules have been emptied, the device cannot be re-used. In -2 -other inhalers, after a capsule has been emptied, it can be replaced with a full one and the device can be reset to its initial condition to be used again.
The present invention relates to dispensers that deliver a substance in powdered form by using a manually operated piston to generate a flow of air, which entrains powder from the capsule. In other respects, it is applicable to all the alternative types of dispenser described above. In particular, dispensers according to the invention may be disposable or re-usable. For simplicity, the invention will be further described in the context of a medical inhaler but, as previously noted, it can also be used for introducing to a powder into an airstream in non-medical contexts.
For reliable operation, the dispenser should preferably be simple to use, for example while it is being applied as an inhaler to the nostrils and therefore not easy for the user to see or manipulate. Particularly in the case of a disposable device, it should preferably also be cost-effective and simple to manufacture.
Medical capsules typically comprise a hollow cylindrical body closed by hemispherical or domed ends. They conform to one of a limited number of defined formats, therefore an inhaler can be defined to accommodate a capsule of known shape and dimensions.
Capsules are supplied containing a defined quantity of the powdered substance and it is important that a high proportion of the substance should be entrained reliably into the airstream to ensure that the patient receives the intended dose of medication.
The capsules containing the powdered medicament are provided in a sealed state so, before powder can be dispensed, the capsule must be opened. In existing dispensers, this typically requires the user to carry out a first step, in which the dispenser is manipulated to open the capsule, followed by a distinct second step, in which a stream of air is caused to pass through the capsule to entrain the powder and dispense it. After the first step, the capsule is open so any change of orientation of the dispenser by the user before the second step creates a risk that powder may escape prematurely from the capsule and may subsequently fail to be dispensed correctly. Conversely, if the action of opening the capsule and delivering the stream of air are not completely sequential -3 -such that air starts to flow before the capsule opening is complete, then there is a risk that some of the air flow would flow around the outside of the capsule, and that some of the powder may be retained in the capsule or not carried through the centre of the needles as intended. The importance of piercing the capsule in a particular way is described in UK patent application 2317756.1 dated 21 November 2023, the contents of which are incorporated herein by reference.
Summary of the invention
The invention provides a powder dispenser comprising a nozzle, a main body and a piston disposed in series along an axis. The nozzle comprises an outlet for dispensing the powder, the nozzle being movable along the axis towards the main body to open a powder capsule that is mounted between the nozzle and the main body. The main body and the piston define between them a cavity that is in fluid communication with the capsule and the outlet. The piston is movable along the axis towards the main body to expel air from the cavity through the open capsule and the outlet. In an initial configuration of the dispenser, when a force greater than or equal to a first threshold force is applied axially between the nozzle and the piston, it causes movement of the nozzle but not movement of the piston. When the nozzle has moved through a predetermined distance towards the main body, the dispenser enters a second configuration, wherein, when a force greater than or equal to a second threshold force is applied axially between the nozzle and the piston, it causes movement of the piston but not movement of the nozzle.
The dispenser is simple to operate because, by the user applying a force continuously between the nozzle and the piston, the required steps are automatically performed in the correct sequence, namely, opening the capsule followed by generating a flow of air through it to dispense the powder. By controlling the second threshold force it is possible to control the pressure and flow rate of the air stream generated by the piston to ensure consistent delivery of the powder without the additional complexity of adding additional feature such as pressure relief valves. -4 -
In some embodiments of the invention, the dispenser further comprises a releasable engagement between the piston and the main body, which resists movement of the piston until the dispenser has entered the second configuration. By restraining movement of the piston until after a predetermined movement of the nozzle has been completed, the releasable engagement ensures that no flow of air through the dispenser can be generated until after the capsule has been opened to release the powder for entrainment.
Such a releasable engagement may comprise a detent on the piston, which releasably engages the main body until, when the nozzle has moved through the predetermined distance, a bump on the nozzle displaces the detent to release the engagement and allow said movement of the piston towards the main body. Such a detent can serve as a latch, which positively locks the piston against movement relative to the main body until the nozzle has moved through the predetermined distance to ensure that the powder capsule is open. This results in a reliable operation compared with, for example, a dispenser than might depend on a balance of competing forces to determine whether it is the nozzle or the piston that moves first relative to the main body. After the detent has been released, only a relatively small force may be required to move the piston.
In the initial configuration of the dispenser, the bump on the nozzle may releasably engage the main body to resist said movement of the nozzle towards the main body if a force less than the first threshold force is applied axially between the nozzle and the piston. Thus the same bump, which subsequently displaces the piston detent to cause the dispenser to enter the second configuration, may serve a dual function in that, when the dispenser is in its initial configuration, the bump secures the nozzle against accidental movement until a force greater or equal to the first threshold force is applied. In alternative embodiments of the invention, the means for securing the nozzle against accidental movement in the initial configuration could be a different bump from the one that displaces the piston detent, or could be any other means that offers some initial resistance, which the user must overcome in order to begin moving the nozzle -5 -Preferably, the main body further comprises a track parallel to the axis; the detent engages the main body by projecting into the track; and, when the nozzle moves towards the main body, the bump on the nozzle follows the track and displaces the detent out of the track when the nozzle has moved through the predetermined distance.
The track (of which there may be more than one) thus controls the axial movement of the nozzle relative to the main body and also ensures that the bump remains aligned with the detent to reliably trigger the second configuration of the dispenser.
Preferably, the piston is received in the main body; the track is on an exterior surface to of the main body and is pierced by an aperture that opens to an interior of the main body; and the detent is resiliently mounted on an exterior of the piston such that the detent can selectively engage the main body by projecting through the aperture into the track. The piston may comprise at least two further detents resiliently mounted on the exterior of the piston, the detents being disposed about the axis such that, when the piston moves towards the main body to expel air from the cavity, the detents slide on an interior wall of the main body to guide the movement of the piston. The detents thereby serve a dual function of locking the piston against movement until the nozzle has moved through the predetermined distance; and thereafter providing a low-friction means for supporting and guiding the movement of the piston within the main body.
In some embodiments of the invention, in a locked configuration of the dispenser, the bump on the nozzle is offset circumferentially from the track to prevent the nozzle moving axially towards the main body; and the nozzle is capable of rotation about the axis relative to the main body to unlock the dispenser by bringing the bump into alignment with the track, the dispenser thereby entering the initial configuration. This provides the additional safety feature that, when the dispenser is in its locked configuration prior to use, the nozzle is unable to move relative to the main body even if subjected to a force greater than the first threshold force. In order to unlock the dispenser to be capable of being activated, the user must first execute a rotation of the nozzle relative to the main body, which is unlikely to happen accidentally. -6 -
In alternative embodiments of the invention, when the dispenser reaches its second configuration, the nozzle mechanically engages the main body to prevent further movement of the nozzle towards the main body. In these embodiments, a releasable engagement between the main body and the piston may not be required because, when the nozzle has travelled through the predetermined distance relative to the main body, it is physically prevented from moving further. Thus, continued application of an axial force between the piston and the nozzle can only result in the movement of the piston towards the main body. However, a detent or other releasable engagement could still be provided in order to control the relative values of the first and second threshold force to and positively to lock the piston against movement until the second configuration has been entered.
In such embodiments, the main body may be received in the piston, rather than the piston being received in the main body. The two parts still define an air cavity between them, which is compressed as the main body and the piston move towards one another.
Preferably, the second threshold force is less than or equal to the first threshold force. This means that, once the user has applied a force between the piston and the nozzle that is sufficient to start the nozzle moving, they need only to maintain the same force in order to complete the remaining steps and deliver powder from the dispenser. If the second threshold force is greater than the first threshold force, then the user may need to apply an increased force at the time when the piston should begin to move, which will interrupt the smooth operation of the dispenser and could lead to unreliable results.
Preferably, in the second configuration of the dispenser, the nozzle is secured to the main body to prevent movement of the nozzle away from the main body. For example, the securing means may comprise crush ribs provided on a sliding interface between the main body and the nozzle. By such means, re-use of a disposable dispenser may be prevented, whether in a futile attempt to re-use it after the capsule has already been emptied, or in an unauthorized attempt to replace the capsule with a new one. -7 -
In some dispensers according to the invention, when the nozzle moves towards the main body, the powder capsule is pierced by a hollow inlet needle on the main body and by a hollow outlet needle on the nozzle. Such piercing typically creates a hole at each end of the capsule, whereby air can flow through it and entrain powder from the capsule into the airstream. Examples of inlet and outlet needles that are suitable for use with the present invention are disclosed in the aforementioned UK patent application 2317756.1.
The invention further provides a method of dispensing powder from a capsule, comprising the steps of: (a) in a dispenser comprising a nozzle, a main body and a piston disposed in series along an axis, mounting the capsule between the nozzle and the main body; (b) applying a force greater than or equal to a first threshold force axially between the nozzle and the piston to cause movement of the nozzle towards the main body but not movement of the piston, whereby the movement of the nozzle opens the powder capsule; and (c) when the nozzle has moved through a predetermined distance towards the main body, applying a force greater than or equal to a second threshold force axially between the nozzle and the piston to cause movement of the piston towards the main body but not movement of the nozzle, whereby the movement of the piston expels air from a cavity defined between the piston and the main body, causing the air to flow through the open capsule, entrain powder from the capsule and dispense it through an outlet in the nozzle.
Some methods according to the invention include the further steps of: before step (b), engaging a detent of the piston with the main body to prevent movement of the piston towards the main body; and in step (c), when the nozzle has moved through the predetermined distance, causing a bump on the nozzle to displace the detent and disengage it from the main body. -8 -
The term "powder" is intended to encompass any solid or semi-solid material that is finely divided into particles, whereby the particles are capable of being entrained in a stream of air or gas. The particles may be rounded or angular, regular or irregular, uniform or non-uniform in their size, shape and material.
Where this specification uses directional terms such as "upper", "lower", they refer to the orientation of the device shown in the drawings, with the axis of the dispenser generally vertical and the nozzle above the piston. This is typical of how some embodiments of the invention may be used as a nasal inhaler. However, the invention is not limited to use in such an orientation and, of course, devices according to the invention may be manufactured, distributed and stored in any orientation while remaining within the scope of the claims.
The drawings Figures 1A, I B and IC are perspective views of a dispenser according to a first embodiment of the invention in successive stages of its operation.
Figure 2 is a cross-sectional front view of the dispenser of Figure 1 in its initial configuration, taken on a plane that includes the axis.
Figure 3 is a side elevation of the dispenser of Figure 1, in which the nozzle part is shown disassembled and in cross-section.
Figure 4 is a cross-sectional front view of the dispenser of Figure 1 in its second configuration, taken on a plane that includes the axis.
Figure 5 is a cross-sectional front view of the dispenser of Figure 1 in its final configuration, taken on a plane that includes the axis.
Figure 6 is a perspective view of part of the main body of the dispenser of Figure 1.
Figure 7 is a cross-sectional view of a dispenser according to a second embodiment of the invention in its initial configuration Figures 8A, 8B and 8C are cross-sectional views of the dispenser of Figure 7 in successive stages of its operation.
The powder dispenser in Figures 1A, 1B and 1C comprises three parts arranged in series along an axis from the top to the bottom of the drawings, namely, a nozzle 2, a main body 4 and a piston 6. The parts 2,4,6 are nested concentrically in the same sequence so that the nozzle 2 receives the main body 4 and the main body 4 receives the piston 6. A projection 8 extends from the nozzle 2 and ends in an outlet 10. The illustrated dispenser is intended for use as a nasal inhaler so the projection 8 is configured to be received in the nostril of a user. When the dispenser is operated, a stream of air is emitted through the outlet 10, carrying powder from a capsule that is mounted inside the dispenser.
Before use, the dispenser is in the fully extended initial configuration shown in Figure 1A. The nozzle 2 is axially spaced from the main body 4 and a powder capsule (not visible in Figure 1A) is mounted on the axis between the nozzle 2 and the main body 4. The piston 6 is also axially spaced from the main body 4 to define an air cavity between the piston 6 and the main body 4.
A user grips the dispenser so as to be able to exert an axial force between the piston 6 and the nozzle 2 For example, the user may hold the dispenser with their thumb pressed against a lower face of the piston 6 and two fingers of the same hand pressed against an upper face of the nozzle 2, on respective sides of the projection 8, in the manner of a syringe. By squeezing their thumb towards the opposing fingers, the user can then move the piston 6 towards the nozzle 2 In accordance with the invention, the applied force results in the nozzle 2 initially moving towards the main body 4, while the piston 6 does not move relative to the main body 4.
The movement of the nozzle 2 towards the main body 4 continues through a predetermined distance, which is sufficient to rupture the powder capsule that is mounted between those two parts. The main body 4 may now be received substantially wholly inside the nozzle 2, as shown in Figure 1B, though this is not essential. The dispenser then enters a second configuration, in which the continuing axial force applied by the user causes the piston 6 to start moving towards the main body 4. In most embodiments of the invention, the nozzle 2 will stop moving in the second configuration of the dispenser but it is not excluded that the movement of the nozzle 2 and the movement of the piston 6 could overlap for a short time.
-10 -As the piston 6 moves towards the main body 4, the cavity defined between those two parts reduces in volume and air is expelled from it to flow through the capsule. The stream of air entrains powder from inside the capsule to carry it through the outlet 10 of the nozzle 2 The piston 6 may continue to move until it is received substantially wholly inside the main body 4, as shown in Figure IC, though this is not essential.
When this specification refers to the parts 2,4,6 moving closer together, it refers to closeness only as measured in a direction parallel to the axis. It is not relevant that some outer regions of those parts may be in radial contact throughout the duration of the axial movement. It should also be understood that only relative movement between the parts is significant: it does not matter whether one part moves while the other is stationary or whether the parts move simultaneously towards one another. For simplicity, we generally treat the main body 4 as the fixed datum, with the nozzle 2 and the piston 6 moving relative to it. However, when the dispenser is used as a nasal inhaler, the nozzle 2 will be held stationary against the user's nostril while both the main body 4 and the piston 6 will move towards it.
Figure 2 is a cross-section through the dispenser of Figure 1A, which shows the internal structures of the respective parts 2,4,6.
The nozzle 2 is generally cup-shaped, comprising a cylindrical skirt 12 that is closed at the upper end by a generally planar end wall 14. The projection 8 extends upwards from the end wall 14 and comprises an internal, axial bore 16, which opens through the end wall 14 and is configured to receive a powder capsule 18. A collar 19 may also extend downwards from the end wall 14 to provide an extension of the bore 16. A passage 20 extends between the bore 16 and the outlet 10. The configuration of the outlet 10 and the upper end of the passage 20 may be designed to create a desired pattern in the airstream that emerges from the outlet 10. This configuration does not form part of the present invention. The lower end of the passage 20 is in fluid communication with the bore 16 via one or more apertures in an outlet needle 24. The outlet needle 24 points downwards along the axis 26 such that, by advancing towards the capsule 18, a tip of the outlet needle 24 may pierce an upper end of the capsule 18 and, when the outlet needle 24 has fully entered the capsule 18, its apertures will provide fluid communication between the outlet passage 20 and the interior of the capsule 18.
The main body 4 is also generally cup-shaped, comprising a cylindrical skirt 28 that is closed at the upper end by a generally planar end wall 30. The outer diameter of the skirt 28 of the main body 4 is slightly smaller than the inner diameter of the skirt 12 of the nozzle 2 so the main body 4 can be received concentrically in the nozzle 2. Air bleed channels 32 are provided on the interior surface of the nozzle skirt 12 and/or on the exterior surface of the main body skirt 28 to allow air to escape from between those parts as they move closer together.
A capsule chamber 34 extends upwards from the end wall 30 of the main body 4. The capsule chamber 34 may be seated in a recess 35 of the end wall 30, which helps to reduce the overall length of the dispenser. The capsule chamber 34 is shaped and sized externally to be slidably received in the bore 16 of the nozzle 2. It is shaped and sized internally to hold the powder capsule 18 on the axis 26 of the dispenser, such that the capsule 18 can slide axially within the capsule chamber 34 but cannot move or tilt significantly in any transverse direction. The main body 4 further comprises an inlet passage 36, the lower end of which opens through the end wall 30 and the upper end of which is in fluid communication with the capsule chamber 34 via one or more apertures in an inlet needle 38. The inlet needle 38 points upwards along the axis 26 such that, by advancing towards the capsule 18, a tip of the inlet needle 38 may pierce a lower end of the capsule 18 and, when the inlet needle 38 has fully entered the capsule 18, its apertures will provide fluid communication between the inlet passage 36 and the interior of the capsule 18.
A number of axially aligned tracks 40 are formed on the exterior surface of the skirt 28 of the main body 4. The tracks 40 are configured as shallow channels, suitable for receiving a corresponding number of bumps 42 that are formed on an interior surface of the skirt 12 of the nozzle 2. It is preferred to provide at least two tracks 40 and -12 -bumps 42, equally angularly spaced about the axis 26. In the illustrated embodiment (best seen in Figure 3) the number of tracks 40 and bumps 42 is three. A retaining recess 43 is provided adjacent to and aligned with the upper end of each track 40, being separated from the track 40 by a small retaining detent 44. In the initial configuration of the dispenser, shown in Figure 2, the bumps 42 of the nozzle 2 rest in the retaining recesses 43. In order for the nozzle 2 to start moving relative to the main body 4, each bump 42 must be pushed past the corresponding detent 44 to enter the track 40. The retaining detents 44 thus hold the dispenser in its initial configuration, to resist said movement of the nozzle 2 towards the main body 4 until the user applies an axial force that is at least equal to a first threshold force. In the embodiment of the invention illustrated in Figures 1 to 6, the first threshold force may be in the range of 5 to 30N.
Close to the lower end of each track 40, its floor is pierced by an aperture 46, which opens to the interior of the main body 4. The purpose of the apertures 46 will be explained below.
The exterior surface of the skirt 28 of the main body 4 may optionally also comprise a number of locking recesses 48, seen in Figure 3. Each locking recess 48 is positioned adjacent to, and angularly offset from, one of the retaining recesses 43 and is separated from it by a small locking detent 50. In a locked configuration of the dispenser, which may be used for safety during transport and storage prior to use, the bumps 42 on the nozzle 2 rest in the locking recesses 48. Because the bumps 42 are angularly offset from the tracks 40, the nozzle 2 cannot move towards the main body 4 even if an axial force is applied. In order to bring the dispenser into the initial configuration ready for use, it must be unlocked by rotating the nozzle 2 relative to the main body 4. This requires sufficient force to push the bumps 42 past the locking detents 50 so that they lodge in the retaining recesses 43 at the tops of the tracks 40. For ease of assembling the nozzle 2 with the main body 4, the locking recesses 48 may be provided at the lower ends of axially aligned access tracks 52. A further set of assembly detents 54 may be provided to resist movement of the bumps 42 back along the access tracks.
Reverting to Figure 2, the piston 6 is generally drum-shaped, comprising a cylindrical skirt 56 that is closed at the upper and lower ends by generally planar end walls 58,60. The upper end wall 58 is unbroken but in the illustrated embodiment it comprises a recess 62 to receive the lower end of the capsule chamber 34. This allows the overall length of the dispenser to be reduced. The lower end wall 60 is pressed by the user to operate the dispenser so it may be profiled to enhance the user's grip, for example, by making it textured or concave. The outer diameter of the skirt 56 of the piston 6 is slightly smaller than the inner diameter of the skirt 28 of the main body 4 so that the piston 6 can be received concentrically in the main body 4. A sealing ring 64 seals between the piston 6 and the main body 4 to create a cavity 66 between them, inside the main body 4, which is air-tight except for the inlet passage 36 that opens through the upper end wall 30 of the main body 4.
A plurality of piston detents 68 are formed on the skirt 56 of the piston 6, each piston detent 68 being mounted on a resilient arm 70 so that in a relaxed state it projects beyond the radius of the skirt 56 but it can be deflected inwards. The number and arrangement of the piston detents 68 corresponds to the number and arrangement of the tracks 40 on the skirt 28 of the main body 4 so that, in the initial configuration of the dispenser, the piston detents 68 spring outwards and engage the apertures 46 of the tracks 40. The detents 68 and apertures 46 are shaped so that, while the detents 68 are lodged in the apertures 46, the piston 6 cannot be moved towards the main body 4 by simply applying an axial force. The detents 68 also prevent the piston 6 being removed from the main body 4. It may be noted that, although the piston 6 takes the general form of a hollow cylinder, with an unbroken upper end wall 58 to maintain the air-tightness of the cavity 66, it is not necessary or desirable for the interior of the piston 6 to be isolated from the atmosphere. One or more openings may be present in the lower end wall 60 or in the skirt 56 of the piston, anywhere below the sealing ring 64. In the illustrated embodiment, those openings surround the resilient arms 70 of the piston detents 68.
From the initial configuration of the dispenser shown in Figure 2, the user applies an axial force between the lower end wall 60 of the piston 6 and the upper end wall 14 of -14 -the nozzle 2. The engagement between the piston detents 68 and the apertures 46 of the main body 4 prevents the piston 6 from moving towards the main body 4. Instead, provided the applied force reaches at least a first threshold sufficient to push the bumps 42 past the retaining detents 44, the nozzle 2 starts to move towards the main body 4, being constrained to move axially by the bumps 42 following the tracks 40.
The movement of the nozzle 2 causes the outlet needle 24 to approach the inlet needle 38 and their tips pierce the respective ends of the powder capsule 18 mounted between them. If required, one of the needles 24,38 may be designed with a sharper tip in order that it should be the first to pierce the capsule 18.
Continued movement of the nozzle 2 towards the main body 4 leads to the second configuration of the dispenser, which is shown in Figure 4. The powder capsule 18 has been pushed to the bottom of the capsule chamber 34 so that the inlet needle 38 fully penetrates it and the apertures of the inlet needle 38 are inside the capsule 18. The outlet needle 24 has advanced fully into the capsule chamber 34 so that it fully penetrates the capsule 18 and the apertures of the outlet needle are inside the capsule 18. Thus the powder capsule 18 has been opened at both ends and an air path through it has been created.
Meanwhile, the bumps 42 on the nozzle 2 have travelled through a predetermined distance along the tracks 40 to reach the apertures 46 in which the piston detents 68 are lodged. The bumps 42 push the piston detents 68 radially inwards, against the force exerted by the resilient arms 70, which releases the engagement between the piston 6 and the main body 4. As the user continues to apply an axial force, provided it is at least equal to a second threshold, the piston 6 starts to move relative to the main body 4.
The piston detents 68 may be formed with a tapering profile so that the applied axial force helps to release them from the apertures 46. Thereafter, the piston detents 68, being sprung radially outwards against the interior wall of the skirt 28 of the main body 4 at intervals around the axis, help to centre the piston 6 in the main body 4 and enable it to slide towards the main body 4 with minimal friction.
-15 -The main resistance to movement of the piston 6 may be offered by air pressure in the cavity 66. This will depend on how easily the displaced air can flow along the air path to the outlet 10 but it is generally kept quite low to ensure that the dispenser is easy to use. Apart from the need to ensure that the piston detents 68 have fully disengaged from the apertures 46, there is no significant resistance to the initial movement of the piston 6, therefore it is preferred that the second threshold force required to cause that movement should be lower than the first threshold force required to cause the movement of the nozzle 2 from the initial configuration of the dispenser. For example, in the embodiment of the invention illustrated in Figures 1 to 6, if the first threshold force is in the range 10N to 30N, the second threshold force may preferably be less than 10N. Accordingly, once the user has begun the operation of the dispenser, they should not experience any increase in the force that needs to be applied, which might cause them to interrupt the operation before it is incomplete.
The engagement of the bumps 42 with the apertures 46 may also serve to prevent further movement of the nozzle 2 towards the main body 4 but this is not essential. In the alternative, such further movement could be prevented by mechanical engagement between the respective end walls 14,30 or between other parts of the nozzle 2 and the main body 4, which may occur at the same time as, or shortly after, the piston 6 starts to move.
As the piston 6 moves towards the main body 4, the volume of the cavity 66 defined between them is reduced and air is displaced from it to flow through the inlet passage 36 and enter the powder capsule 18. The stream of air flowing through the capsule 18 entrains powder from the capsule and carries it through the outlet passage 20 to the outlet 10 of the dispenser. The volume of air displaced from the cavity 66 is designed to be sufficient to entrain the entire dose of powder contained in the capsule 18 by the time the dispenser reaches its final configuration, shown in Figure 5. In the final configuration, the piston 6 is preferably fully received in the main body 4 and the volume of the cavity 66 between them has been reduced close to zero. That is not essential for operation of the invention but helps to reduce the overall length of the dispenser.
-16 -The dispenser according to the illustrated embodiment of the invention is intended for single use. To ensure that no attempt can be made to re-use the dispenser, it is desirable that it should be locked after the first use as been completed. One way to do this is illustrated in Figure 6. This shows the capsule chamber 34 extending from the recess 35 in the end wall 30 of the main body 4. Crush ribs 72 are provided around the inside of the recess 35, on both its inner and outer walls. At the end of movement of the nozzle 2 towards the main body 4, the collar 19 of the nozzle is received in the recess 35 of the main body, as seen in Figure 4. The crush ribs 72 create an interference fit with the collar 19, which prevents the nozzle 2 from easily being moved away from the main body 4, especially as there is no longer any easy access that would allow a user to grip the main body 4. The opened powder capsule 18 is thereby securely enclosed between the nozzle 2 and the main body 4 and it becomes impossible to reuse the dispenser. It will be understood that similar crush ribs could be provided between other surfaces that come into sliding engagement near the end of the movement of the nozzle 2 towards the main body 4, or near the end of the movement of piston 6 towards the main body 4. Alternative means such as a snap-fit coupling (not illustrated) could be provided to achieve a similar result. It may further be noted that when the piston 6 has been fully received in the main body 4, as shown in Figure 5, there is no longer any easy access that would allow a user to grip the piston 6 to try to remove it again.
Figure 7 is a cross-section of a second embodiment of dispenser according to the invention. To the extent that the parts of the dispenser operate in the same way as in the first embodiment, they will not be described in detail again. As in the first embodiment, the dispenser comprises a nozzle 102, a main body 104 and a piston 106 arranged in series along the axis 126. Those parts 102,104,106 are also nested concentrically but in this embodiment the nozzle 102 receives the piston 106 and the piston 106 receives the main body 104.
-17 -A projection 108 extends from the nozzle 102 and ends in an outlet 110. Apart from a change in certain proportions, the design of the nozzle 102 is substantially the same as the nozzle 2 of the first embodiment.
The main body 104 is once again generally cup-shaped but this time its cylindrical skirt 128 is closed at the lower end by a generally planar end wall 130. A capsule chamber 134 extends upwards from the end wall 130 of the main body 104. It is shaped and sized externally to be slidably received in a bore 116 of the nozzle 102 and is shaped and sized internally to hold a powder capsule 118 on the axis 126 of the dispenser. The main body 104 further comprises an inlet passage 136, the lower end of which opens through the end wall 130 and the upper end of which is in fluid communication with the capsule chamber 134 via one or more apertures in an inlet needle 138.
In this embodiment, the piston 106 is also generally cup-shaped, comprising a cylindrical skirt 156 that is closed at the lower end by a generally planar end wall 160. The outer diameter of the skirt 156 of the piston 106 is slightly smaller than the inner diameter of the skirt 112 of the nozzle 102 so that the piston 106 can be received concentrically in the nozzle 102. The inner diameter of the skirt 156 of the piston 106 is slightly larger than the outer diameter of the skirt 128 of the main body 104 so that the main body 104 can be received concentrically in the piston 106. A sealing ring 164 seals between the main body 104 and the piston 106 to create a cavity 166 between them, inside the piston 106, which is air-tight except for the inlet passage 36 that opens through the lower end wall 130 of the main body 104.
Figures 8A to 8C illustrate the sequence of operation of the dispenser according to the second embodiment of the invention. Figure 8A is identical to Figure 7 and shows the dispenser in its initial configuration. To operate the dispenser, the user applies an axial force between the lower end wall 160 of the piston 106 and the upper end wall 114 of the nozzle 102. Provided the applied force is at least equal to a first threshold force, the nozzle 102 starts to move towards the main body 104, while the piston 106 does not move. The reasons why the nozzle 102 should move preferentially are discussed below.
-18 -The movement of the nozzle 102 causes the outlet needle 124 to approach the inlet needle 138 and their tips pierce the respective ends of the powder capsule 118 mounted between them.
Continued movement of the nozzle 102 towards the main body 104 leads to the second configuration of the dispenser, which is shown in Figure 8B. The powder capsule 118 has been pushed to the bottom of the capsule chamber 134 so that the inlet needle 138 fully penetrates it and the apertures of the inlet needle 138 are inside the capsule 118. The outlet needle 124 has advanced fully into the capsule chamber 134 so that it fully penetrates the capsule 118 and the apertures of the outlet needle are inside the capsule 118. Thus the powder capsule 118 has been opened at both ends and an air path through it has been created.
The nozzle 102 has now moved through a predetermined distance towards the main body 104, such that an upper rim 129 of the skirt 128 of the main body 104 mechanically engages the upper end wall 114 of the nozzle 102 by butting against it. As a result, the nozzle 102 can move no further. As the user continues to apply an axial force, provided it is at least equal to a second threshold force, the piston 106 starts to move relative to the main body 104. As the piston 106 moves towards the main body 104, the volume of the cavity 166 defined between them is reduced and air is displaced from it to flow through the inlet passage 136 and enter the powder capsule 118. The stream of air flowing through the capsule 118 entrains powder from the capsule and carries it through the outlet passage 120 to the outlet 110 of the dispenser. The volume of air displaced from the cavity 166 is designed to be sufficient to entrain the entire dose of powder contained in the capsule 118 by the time the dispenser reaches its final configuration, shown in Figure 8C. In the final configuration, the piston 106 is preferably fully received in the nozzle 102.
As previously noted, when an axial force is applied to the dispenser in the initial configuration, then in accordance with the invention the nozzle 102 moves relative to the main body 104 in preference to the piston 106. This may be because of the resistance to movement of the piston 106 that is offered by the air pressure in the -19 -cavity 166 (especially prior to opening of the capsule) and by the resilient sealing ring 164. The aforementioned guides (not illustrated) may also be designed such that the nozzle 102 experiences lower frictional forces than the piston 106 and should therefore move first. For a more positive control of the balance of forces, simple detents (not shown in Figure 7) of the kind previously discussed may provide initial resistance to the movement of the piston 106.
Alternatively, a system (not illustrated) similar to the piston detents 68 of the first embodiment could be provided to lock the piston 106 positively against movement until the nozzle 102 has moved through a predetermined distance. In this case, the tracks would be formed on the exterior surface of the skirt 156 of the piston 106. As before, the bumps would be on the interior surface of the skirt 112 of the nozzle 102 and would move along the tracks. The detents would be mounted on resilient arms on the main body 104 so as to engage releasably in apertures at the ends of the tracks. When the nozzle 102 has moved through the predetermined distance towards the main body 104 to reach the second configuration, the bumps on the nozzle 102 enter the apertures in the piston 106 and displace the detents of the main body 104 radially inwards. This releases the piston 106 to move towards the main body 104. At the same time, the piston 106 must also move towards the nozzle 102, therefore the bumps on the nozzle 102 cannot lodge permanently in the apertures of the piston 106 but, having displaced the detents from the apertures, must themselves also be released from the apertures and continue moving along the tracks. Therefore, in this embodiment, the apertures in the tracks would be part-way along, not at their ends.