Abstract:
A device ( 20 ) is disclosed for dispensing a fluid supplied from an external fluid source. The device comprises a transducer ( 32 ) adapted to receive a fluid from the fluid source, and a collapsible linkage and trip link ( 502 ) coupling the transducer and the fluid source. The linkage has a collapsible joint inhibiting discharge of the fluid source when in a locked orientation. The device ( 20 ) further comprises a moveable member coupled to the linkage such that inhalation forces on the device cause the linkage to collapse thereby discharging the fluid from the fluid source. The device may further include a dose counter coupled to the fluid source for registering the amount of doses administered from the fluid source.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a filing under 35 U.S.C. 371 of International Application No. PCT/GB2015/050866 filed Mar. 24, 2015, entitled “Inhaler Device,” which claims priority to Indian Patent Application No. 1159/MUM/2014 filed Mar. 29, 2014, which applications are incorporated by reference herein in their entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention pertains generally to metered dose inhalers and, more specifically, to a metered dose inhaler with a breath actuated delivery mechanism and dose counter. 
       BACKGROUND OF THE INVENTION 
       [0003]    Inhalers are commonly used to deliver a wide range of medicaments to the bronchial passages, lungs and bloodstream of the user. Typical inhalers hold a container of pressurized medicament and propellant that is actuatable, generally by compression, to deliver a dose of medicament through a mouthpiece to the patient. 
         [0004]    It is generally desirable for the dose of medication to be dispensed at the same time that the patient inhales air to permit the majority of medication to enter the lung rather than the mouth or esophagus. A number of inhalers have been developed that use breath actuated devices to automatically initiate the discharge of the medicament from the container when the patient inhales. Many of these devices, such as U.S. Pat. No. 5,069,204 to Smith et al., use latching mechanisms that require a considerable amount of air pressure to release the medicament. These higher release pressures lead to difficulty of use, and discharge at non-optimal points in the patient&#39;s breath cycle. 
         [0005]    The devices described in WO 2005/007226 and WO 2007/066140 are actuated with lower release pressures and are therefore more readily used by patients. However, the arrangements of these devices is such as to render assembly of the devices difficult and/or slow, particularly in relation to automated mass production. 
         [0006]    It is therefore an object of the present invention to provide a breath-actuated inhaler device which is comparatively simple and/or quick to assemble. 
       SUMMARY OF THE INVENTION 
       [0007]    A first aspect of the present invention provides an inhaler for dispensing metered doses of a medicament, the inhaler comprising a housing, an actuator member ( 508 ) moveable relative to the housing; a first link member ( 504 ) for coupling with a container of medicament; and a restraining surface ( 514 ) connectable with the first link member ( 504 ) for restraining movement of the first link member ( 504 ) from a first position, in which the medicament container is located in a stowed configuration, to a second position, in which the medicament container is located in a discharge configuration so as to dispense medicament; wherein the restraining surface ( 514 ) is moveable from a restraining position in response to movement of the actuator member ( 508 ) from a nominal position so as to allow movement of the first link member ( 504 ) from the first position to the second position; characterised in that the inhaler further comprises an elastically and resiliently deformable member ( 36 ) arranged adjacent the actuator member ( 508 ) so as to be compressed and thereby bias the actuator member ( 508 ) towards said nominal position. 
         [0008]    Ideally, the deformable member ( 36 ) has an annular shape. 
         [0009]    A circular hole defined by the annular shape of the deformable member ( 36 ) may receive a circular boss ( 94 ). 
         [0010]    It is preferable that the diameter of the circular boss ( 94 ) is equal to or larger than the diameter of said hole defined by the annular shape of the deformable member ( 36 ) so that the boss ( 94 ) receives the deformable member ( 36 ) with an interference fit therebetween. 
         [0011]    Furthermore, the boss ( 94 ) and deformable member ( 36 ) may be located adjacent a first side of the actuator member ( 508 ) and a second boss and second deformable member ( 36 ) may be located adjacent a second side of the actuator member ( 508 ) opposite said first side of the actuator member ( 508 ). 
         [0012]    The actuator member ( 508 ) may comprise a projection ( 96 ) which extends therefrom so as to abut a deformable member ( 36 ). 
         [0013]    It is preferable that the actuator member ( 508 ) comprises two projections ( 96 ), each projection ( 96 ) extending from a different opposite end of a hinge pin ( 98 ) and abutting a different deformable member ( 36 ). 
         [0014]    The arrangement of projection ( 96 ) and deformable member ( 36 ) on a first side of the actuator member ( 508 ) relative to the opposite second side of the actuator member ( 508 ) may be asymmetric. 
         [0015]    Ideally, said arrangement is asymmetric by virtue of two projections ( 96 ) located on either side of the actuator member ( 508 ) being arranged at an angle to one another. 
         [0016]    A second aspect of the present invention provides an inhaler for dispensing metered doses of a medicament, the inhaler comprising a housing, an actuator member ( 508 ) moveable relative to the housing; a first link member ( 504 ) for coupling with a container of medicament; and a restraining surface ( 514 ) connectable with the first link member ( 504 ) for restraining movement of the first link member ( 504 ) from a first position, in which the medicament container is located in a stowed configuration, to a second position, in which the medicament container is located in a discharge configuration so as to dispense medicament; wherein the restraining surface ( 514 ) is moveable from a restraining position in response to movement of the actuator member ( 508 ) so as to allow movement of the first link member ( 504 ) from the first position to the second position; characterised in that the inhaler further comprises an elastically and resiliently deformable member ( 536 ) arranged adjacent the first link member ( 504 ) so as to be compressed and thereby bias the first link member ( 504 ) towards said first position. 
         [0017]    Preferably, said deformable member ( 536 ) is a helical compression spring. It is also preferable for an end of said deformable member ( 536 ) to be retained in a desired position by virtue of said end being received by a boss ( 537 ). 
         [0018]    The restraining surface ( 514 ) may be connectable with the first link member ( 504 ) by means of a trip link member ( 502 ) rotatably mounted to the housing. 
         [0019]    The first link member ( 504 ) may be positioned relative to the trip link member so as to rotate the trip link member in a first rotary direction when moving from said first position to said second position; and the restraining surface ( 514 ) may be positioned relative to the trip link member, when in said restraining position, so as to restrain rotation of the trip link member in said first rotary direction. 
         [0020]    It is preferable that the restraining surface ( 514 ) abuts a contact surface ( 512 ) of the trip link member when in said restraining position, and wherein the restraining and contact surfaces ( 514 ,  512 ) are arranged so as to slide relative to, and in abutment with, one another as the restraining surface is moved from the restraining position. 
         [0021]    It is further preferable that the restraining surface is moveable from said restraining position along a part-circular path having a centre of curvature coincident with an axis about which the restraining surface is rotably mounted to the housing; and wherein said contact surface ( 512 ) has a part-cylindrical shape with a centre of curvature coincident with said axis of the restraining surface. 
         [0022]    The restraining surface ( 514 ) may have a part-cylindrical shape with a center of curvature coincident with said axis about which the restraining surface is rotatably mounted. The first link member ( 504 ), when in said first position, is ideally located in a groove in the trip link member ( 502 ) and abuts a first side ( 510 ) of said groove. 
         [0023]    The arrangement of the first link member ( 504 ) and the trip link member ( 502 ) may be such that the first link member ( 504 ), when in said second position, is spaced from the trip link member ( 502 ). 
         [0024]    It is preferable that the first link member ( 504 ) is positioned relative to the trip link member so as to rotate the trip link member ( 502 ) when moving from said second position to said first position, the trip link member being rotated into a restrained position in which the restraining surface ( 514 ) is connectable therewith so as to restrain movement of the trip link member ( 502 ). The trip link member ( 502 ) may comprise a guide surface ( 524 ) for guiding the restraining surface ( 514 ) to the restraining position as the trip link member is rotated towards the restrained position. 
         [0025]    Also, the guide surface ( 524 ) may cam the actuator member ( 508 ) as the trip link member ( 502 ) is rotated towards the restrained position. The restraining surface ( 514 ) is preferably provided on the actuator member ( 508 ). The actuator member ( 508 ) may be arranged so as to be moved, in use, in response to the inhalation of a user. Furthermore, the actuator member ( 508 ) is ideally a flap pivotally mounted to the housing. 
         [0026]    Further aspects of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Embodiments of the present invention will now be described with reference to the following drawings which are for illustrative purposes only and in which: 
           [0028]      FIG. 1A  is a first exploded view of an inhaler device according to the present invention, including a breath actuated release mechanism; 
           [0029]      FIG. 1B  is a second exploded view of the inhaler device of  FIG. 1A , including a breath actuated release mechanism; 
           [0030]      FIG. 2A  is a first exploded view of a transducer of the inhaler device shown in  FIG. 1 , including a breath actuated release mechanism; 
           [0031]      FIG. 2B  is a second exploded view of the transducer of  FIG. 2A , including a breath actuated release mechanism; 
           [0032]      FIG. 3A-D  is a schematic view illustrating motion of the breath actuated mechanism; and 
           [0033]      FIG. 4 . is a cross-sectional schematic view the transducer of  FIG. 2A  with the fluid source in a stowed configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Referring more specifically to the drawings, for illustrative purposes the present invention is embodied in the apparatus generally shown in  FIGS. 1A, 1B, 2A and 2B ,  FIGS. 3A-D  and  FIG. 4 . It will be appreciated that the apparatus may vary as to configuration and as to details of the parts, and that the method of operation may vary as to the specific steps and sequence, without departing from the basic concepts as disclosed herein. 
         [0035]    Referring first to  FIGS. 1A and 1B , an inhaler  20  of the present invention is shown in an exploded view with a breath actuation assembly  100  and a dose counter assembly  130 . The breath actuation assembly  100  and the dose counter assembly  130  are housed along with medicament fluid source  22  inside a main body  42 , mouthpiece portion  44 , and top cap  54 , all preferably comprising medical grade plastic or other suitable materials known in the art. Once assembled, the main body  42  and mouthpiece portion  44  are ultrasonically welded to one another. The main body  42  and mouthpiece portion  44  are thereby secured to one another. It will be appreciated that the main body  42  and mouthpiece portion  44  may be secured to one another by other means, for example, such as by means of adhesive. 
         [0036]    Fluid source  22  comprises a conventional Metered Dose Inhaler (MDI) container or other propellant based medicament readily available in the art. Fluid source  22  generally comprises a container  108  holding a mixture of medicament and propellant, and a nozzle  110 , which is in line with a discharge axis  86  of the container  108 , as shown in  FIG. 1A . When the container  108  is advanced relative to the nozzle  110  in the direction of the discharge axis  86  (i.e. the nozzle  110  is pushed into the container  108 ), the medicament is discharged out the nozzle  110  in the direction of the discharge axis  86 . 
         [0037]    The inhaler  20  further includes a dust cover  40  pivotally mounted to cover an inhalation horn  58 . The dust cover  40  may be rotated away from horn  58  to expose an opening  60 . A manual release button  62  is also provided so as to extend through an aperture in the mouthpiece portion  44 . 
         [0038]    Referring also to  FIGS. 1, 2 and 3 , the breath actuation assembly  100  comprises a housing or transducer  32  that rotatably houses lower link  504  at pivot  78 . Lower link  504  is connected to upper link  506  at collapsible joint  66 . Container holder  24  is shaped to receive the nozzle end of container  108  such that the nozzle  110  passes through to contact surface  112  of the transducer  32 . Container holder  24  also has a pair of guides  122  having slots  90  sized to house a pair of bosses  516  as shown in  FIG. 2  at the upper end of upper link  506 . 
         [0039]    As shown in  FIGS. 2A and 2B  in particular, flap  508  is rotatably mounted to the transducer  32  via a peg  98 , which extends across the top surface of flap  508 , and holes  114  in the sidewalls of transducer  32 . The holes  114  may be provided as slots into which the peg  98  is snap fitted during assembly of the apparatus. This allows ready assembly of the flap  508  to the transducer  32  by simply pressing the peg  98  of the flap  508  into the slots  114 . Due to the snap fit nature of the peg  98  in the slots  114 , the flap  508  is retained in a connection with the transducer  32  which allows rotation of the flap  508  relative to the transducer  32 . The bottom and side extremities of flap  508  are sized to fit within the internal surface of transducer  32  to form gap between the flap  508  and said internal surface. The flap  508  has an upper restraining surface  514  configured, in combination with a trip link  502 , to retain an arm of lower link  504  when the flap is in its nominal position shown in  FIG. 3A . 
         [0040]    As illustrated in  FIG. 4 , the transducer  32  is configured to receive nozzle  110  of fluid source  22  at surface  112 . The transducer also comprises an inlet  106  that spans from surface  112  to a first chamber  102 . The inlet  106  is configured to be in line with the nozzle  110  and discharge axis  86  such that medicament discharged from the fluid source  22  is received through the inlet  106  and downstream into first chamber  102 . 
         [0041]    The transducer  32  is also configured to receive plug  38  having bluff surface  104 . Fluid entering chamber  102  through inlet  106  is dispersed and redirected by plug  38  and into outlet  124  that terminates downstream at a second chamber  64 . 
         [0042]    The fluid source  22  is biased to discharge along axis  86  by compressing a loading member, such as biasing spring  48 , between the top cap  54  and container sleeve  46 , which is adapted to receive the other end of the container  108  opposite the nozzle  110 . Biasing spring  48  preloads the container  108  to move in the direction of surface  112  of transducer  32  along the discharge axis  86 . 
         [0043]    In the stowed configuration shown in  FIG. 3A , the fluid source container  108  is retained from translating along axis  86  by a collapsible linkage comprising upper link  506  and lower link  504 . Upper link  506  and lower link  504  are rotatably coupled at a collapsible knee-type joint  66 . The upper end of upper link  506  has a pair of bosses  516  that are retained by a pair of guides  122  in the container holder  24  having slots  90 . The guides are generally in-line, or at least parallel, with the discharge axis  86 , and allow motion of the bosses  516  of the upper link to slideably translate upward and downward in the discharge axis  86 , as well as allow the boss to rotate as necessary. The lower link  504  has one end fixed to the transducer  32  at pivot  78 . As illustrated in  FIG. 3A , the boss  516  of the upper link  506  and pivot  78  of the lower link are essentially in-line with discharge axis  86 , i.e. they form a loading path that is parallel to, or aligned with, the discharge axis  86 . Because collapsible joint  66  is off-center, i.e. positioned away from the loading path formed by the boss  516  of the upper link  506  and pivot  78 , the downward force imposed by biasing spring  48  on the container  108  in the stowed position predisposes the knee joint  66  to collapse. Such collapse is restrained in the stowed position by imposition of the lower link  504  on the trip link  502  and, in turn, by imposition of the trip link  502  on the flap  508 . 
         [0044]      FIG. 3B  illustrates the initiation of the breath actuation mechanism  100  caused by inhalation by a patient through the opening  60  of horn  58 . An outward airflow is created in the second chamber  64 , which pulls through a plurality of slots  70  in the transducer (see  FIG. 4 ). Suction of air through slots  70  creates a small pressure differential across the inner surface of flap  508 , causing the flap to rotate about peg  98  and into the cavity of the transducer  32 , as illustrated in  FIGS. 3B-3D . The gap between the flap  508  and the transducer  32  provides enough clearance to allow the flap to rotate into the cavity of the transducer, while also being small enough to allow a pressure differential with minimal suction on the horn. As the flap  508  rotates, the lower link  504  is no longer retained by the upper surface  514  of the flap, and the lower link  504  clears the flap  508  as the lower link  504  is allowed to rotate about pivot  78 . 
         [0045]    The breath actuation of the inhaler device, through use of breath actuation linkage  500  including the trip link  502  arrangement, will now be described in greater detail. In this regard,  FIG. 3A  illustrates the breath actuation mechanism in a ready (non-actuated, and loaded) state. It will be noted that rather than interfacing directly with flap  508 , the lower link  504  interfaces indirectly with flap  508  via the trip link  502 . The upper link  506  and lower link  504  retain motion of the fluid source  22  and load F from biasing spring via locking knee joint  66 . Knee joint  66  is located off-center from the load F in discharge axis  86  (i.e. the discharge axis  86  passes through pivot  78  and the boss  516  of upper link  506  throughout  FIGS. 3A-D ), and thus the downward force imposed by biasing spring  48  on the container  108  in the ready state/position predisposes the knee joint  66  to collapse. 
         [0046]    The upper link  506  and lower link  504  are restrained from rotating or collapsing because the lower link  504  is locked from rotation by a catch, or trip edge  510  in trip link  502 . Trip link  502  is locked from rotating because of impingement of upper surface (contact surface)  512  of the trip link  502  with a restraining surface, or circular cutout  514 , in the flap  508 . 
         [0047]    Referring now to  FIG. 3B , when the flap  508  rotates due to the force created by patient inhalation (vacuum), upper edge  512  of the trip link clears the cutout  514 , allowing the trip link  502  to rotate clockwise (as viewed in  FIG. 3 ). Trip edge  510  correspondingly rotates to release the contacting surface of the lower link  504   
         [0048]    With lower link  504  now unrestrained, as shown in  FIG. 3C , knee joint  66  collapses and shifts to the left. Because of constraints on the top edges of upper link  506  with container holder  24 , the upper link can only travel in line with the force load path F, and the trip link  502  further rotates clockwise (as viewed in  FIG. 3 ), causing the lower link  504  to further rotate counter-clockwise (as viewed in  FIG. 3 ). 
         [0049]    Referring now to  FIG. 3D , the mechanism further collapses as the lower link  504  continues to rotate counter-clockwise on joint  78 , and upper link  506  travels down allowing the MDI canister  22  to travel downward causing the valve stem to activate. 
         [0050]    After activation, the canister travels upwards such that the knee joint moves back towards its stowed orientation with lower link  504  rotating clockwise towards trip link  502 . The trip link  502  is able to catch lower link  504  in trip edge  510  for retention of the knee joint  66  until subsequent breath actuation of flap  508 . 
         [0051]    The knee joint is moved back towards its stowed orientation by two return compression springs  536  (each in the form of a helical compression spring) which are elastically and resiliently compressed, and also elastically and resiliently bent, between the lower link  504  and transducer  32  when the linkage moves towards the collapsed configuration. The compression springs thereby tend to bias (i.e. return) the linkage into the locked position. 
         [0052]    One compression spring  536  is shown (schematically represented) in  FIG. 3A  only. For the purposes of clarity, no return springs  536  are shown in  FIGS. 3B-D . 
         [0053]    Each compression spring  536  has a first end abutting the lower link  504  and a second end, opposite the first end, abutting an internal surface of the transducer  32 . Bosses  537  may be provided projecting from the lower link  504  and the internal surface of the transducer  32 , and located within the circular ends of the compression springs  536 . The two bosses  537  (one for each spring  536 ) projecting from the lower link  504  are provided on either end of a single unitary member  670 . This member  670  clips (or is otherwise secured, for example, by means of adhesive) to the lower link  504 . For example, the member  670  may resiliently and elastically snap fit between free end portions  680  of two elongate elements  690  of the lower link  504  (see  FIGS. 2A, 2B and 3A ). Accordingly, each end of each compression spring is located about a boss  537  and is thereby retained in position by the respective boss  537  adjacent the lower link  504  or internal surface of the transducer  32 . In the accompanying drawings, only one boss  537  is shown (which extends from the lower link  504  of the schematic arrangement of  FIG. 3 ). 
         [0054]    The flap  508  is returned to its nominal position in the same way as for the embodiment of  FIG. 1 . 
         [0055]    The use of the trip link  502  assists in expanding the operational margin of the lower link  504  with the flap  508 , improving overlap on trip edges to ease manufacturing tolerances while maintaining breath actuation sensitivity. 
         [0056]    In particular, the addition of the trip link  502  expands the operational margin of the lower link  504  with the flap  508  in that, when in the ready state, the inhaler is less prone to accidental actuation as a result of a sudden movement or vibration of the inhaler which causes an unintended rotation of the flap  508 . With reference to  FIG. 3A , it will be seen that the amount of overlap between the cutout surface  514  and the meeting upper edge  512  is sufficient for the flap  508  be able to rotate a considerable distance without the trip link  502  being released so as to allow the knee joint  66  to collapse. Since the mating surfaces  514 ,  512  have a cylindrical shape with a concentric curvature, the area of contact between the flap  508  and trip link  502  remains comparatively large until just before the trip link  502  is released. This also contributes to rendering it more difficult to accidentally actuate the inhaler. 
         [0057]    Furthermore, after actuation, the canister travels upward and the lower link  504  engages the trip link  502 . An end  520  of the lower link  504  engages a portion  522  of the trip link  502  and pushes the trip link  502  so as to rotate said link  502  in an anti-clockwise direction ( FIG. 3D ). As the trip link  502  so rotates, the flap  508  may be cammed along a surface  524  of the trip link  502 . The surface  524  is configured relative to the rotational axis of the trip link  502  so as to engage with the flap  508  in such a way that rotation of the trip link  502  is not prevented by the engagement therewith of the flap  508 . The arrangement of the trip link surface  524  may be such that said surface is cylindrical with a center of curvature coincident with the rotational axis of the trip link  502 . In this way, as the trip link  502  rotates in an anti-clockwise direction (as viewed in  FIG. 3 ), the engagement between the flap  508  and trip link surface  524  is such that the flap  508  is not itself rotated. However, the surface  524  may be arranged so that, as the trip link  502  rotates in an anti-clockwise direction, the surface  524  allows a camming of the flap  508  back towards a ready state position. It will be understood therefore that the surface  524  facilitates a return of the linkage and flap  508  back to the ready state position and ensures a movement of the linkage back to this position is not prevented by the flap  508 . In the schematic arrangement shown in  FIG. 3 , the surface  524  is arranged on the trip link  502  adjacent the upper edge  512 . 
         [0058]    As the lower link  504  pushes the trip link  502  in the anti-clockwise direction, the end  520  of the lower link  504  cams into a groove  526  partly defined by trip edge  510 . 
         [0059]    With rotation of the lower link  504  as shown in  FIG. 3C , the collapsible joint  66  moves over center (i.e. the joint  66  moves yet further away from the loading path formed by the boss  516  of the upper link  506  and pivot  78 ), allowing the container holder  24  and container  108  to translate downward along axis  86 , forcing a portion of the nozzle  110  into the container  108  to stimulate discharge of the medicament from the container  108 . The medicament travels through the first chamber  102  and into the second chamber  64  where it is entrained with air flowing through slots  70 , as described in further detail in U.S. Pat. No. 4,972,830, incorporated by reference. In the embodiment shown, the second chamber  64  has an internal cross section that is shaped like a parabola. The entrained medicament flows through the second chamber  64  and out of the opening  60  of horn  58  to be inhaled by the patient. Therefore, the release of the metered dose of medicament is timed to be inhaled by the patient at an optimal moment during the inhalation phase of the patient&#39;s breath cycle. 
         [0060]    After the inhalation of the dose by the patient, the flap is returned to its nominal position shown in  FIG. 3D  by a return force exerted by flap springs  36 . Rotation of the flap compresses each spring to create a return force to return the flap  508  to its nominal position after the inhalation forces have subsided. 
         [0061]    The flap springs  36  are elastically and resiliently deformable members mounted to the exterior of opposite sides of the transducer  32 . Each flap spring  36  may be manufactured from silicon or similar material known to a person skilled in the art. Furthermore, each spring  36  may be provided in the form of a pad. More specifically, each flap spring  36  has an annular/ring shape and the circular hole formed by this shape receives a circular boss  94  extending from each of said opposite side of the transducer  32 . The diameter of each circular boss  94  is equal to or ideally larger than the diameter of said hole in flap spring  36  associated with said boss  94  so that an interference fit is provided between the boss  94  and flap spring  36  when the flap spring  36  is pressed onto the boss  94  during assembly. The flap spring  36  is thereby retained on the boss  94  (see  FIGS. 2A and 2B  in particular). It will be understood that pressing a flap spring  36  on to one of the bosses  94  is a simple process step allowing a ready and reliable assembly of the apparatus. Each flap spring  36  may be provided as a rubber washer or an O-ring. 
         [0062]    The flap  508  is provided with two projections  96  (see  FIGS. 1A to 2B ) which extend from the peg  98 . Specifically, each projection  96  extends from a different opposite end of the peg  98 . Furthermore, each projection  96  extends so as to be parallel with the plane in which the flap  508  lies. The flap  508 , peg  98  and projections  96  are fixed relative to one another such that, as the flap  508  rotates (permitted by rotation of the peg  98  in the holes or slots  114 ), the projections  96  also rotate. In the assembled apparatus, each projection is located to the exterior of said opposite sides of the transducer  32 , and relative to the flap spring  36  and associated boss  94 , so that the flap springs  36  abut the projections  96  when the flap  508  is in its nominal. As the flap  508  rotates from the nominal position, the projections  96  rotate and compress (i.e. flatten or reduce in dimension, rather than bend or twist as in the case of a leaf spring or torsion spring respectively) one circumferential section of the flap springs  36  with which they abut. As the flap  508  increasingly rotates, the flap springs  36  are increasingly compressed in an elastic and resilient fashion. The flap  508  is thereby biased towards its nominal position by means of the flap springs  36  pressing back against the projections  96 . 
         [0063]    It will be understood that the return force applied to the flap  508  may be adjusted in different embodiments by changing the material from which the flap springs  36  are made and/or by changing the size of the flap springs  36 . The return force may also be adjusted by adopting an asymmetric arrangement of the flap springs  36  and projections  96  such that the arrangement of spring/projection on one side of the transducer  32  is different to that on the other side of the transducer  32 . For example, the material and/or size of the spring  36  on one side of the transducer  32  may be different to that on the other side. The relative position of the spring  36  and projection  96  on one side of the transducer  32  may be different to that on the other side. This may, for example, result in an initial movement of the flap  508  from its nominal position to a second position causing compression of only one flap spring  36 , with the second flap spring  36  being abutted and compressed by the second projection  96  only with rotation of the flap  508  continuing from said second position of flap  508 . This arrangement could take the form of the two projections  96  being arranged at an angle to one another rather than parallel to one another as shown in the accompanying drawings. 
         [0064]    In an alternative embodiment, each flap spring could be an elastically and resiliently deformable member in the shape of a solid or hollow cylinder. Such a deformable member may extend from a side of the transducer  32 . The deformable member could be secured adjacent the side of the transducer  32  by one of numerous means, for example, by means of an adhesive, or alternatively the side of the transducer  32  could be provided with a hole in which the deformable member is held. 
         [0065]    The upper and lower links  506 ,  504 , container holder  24 , and container  108  remain in the collapsed discharge position as seen in  FIG. 3D  due to the force imposed by the biasing spring  48 . The return of the dust cover  40  to cover the horn  58  manually forces the container holder  24  and container  108  to return to the stowed position under compression from biasing spring  48 . As mentioned above, the links  504 , 506  are biased towards the position shown in  FIG. 3A  by a compression spring (for example, a helical compression spring) which is increasingly elastically and resiliently compressed (and perhaps also elastically and resiliently bent) between the lower link  504  and transducer  32  when the linkage moves towards the collapsed configuration shown in  FIG. 3D . The compression spring thereby tends to bias the linkage into the locked position. The collapsible joint  66  is thus retained from collapsing once the dust cover  40  is again opened. The operation of the dust cover  40  will now be described. In the present embodiment, the dust cover  40  not only serves as a shield to cover horn opening/entrance  60 , but it also serves to reset the container to the stowed position after discharge of the medicament. In the stowed position/configuration, the inhaler  20  is arranged with the dust cover  40  shielding the entrance  60  to horn  58  and the links  504 , 506  positioned as shown in  FIG. 3A . The dust cover  40  is pivotably connected to the transducer  32  such that it can be rotated out of place to allow access to the horn opening  60 . The dust cover  40  has two cams  120  (see  FIG. 1A ), which are configured to engage the bottom surface of the guides  122  of the container holder  24  through its entire range of motion along axis  86 . When the dust cover  40  is rotated about a pivot arrangement  118  (shown in  FIG. 1A ) so as to open the entrance  60  to the horn  58 , the cams disengage with the guides  122 . The container holder  24  and container  108  remain in the stowed position, as shown in  FIG. 3A , because of the orientation of the collapsible linkage being retained by the rotational locking of the lower link  504  by the trip edge  510  in trip link  502 . 
         [0066]      FIG. 3D  illustrates the breath actuation assembly  100  in the collapsed configuration with the container holder  24  and container  108  in the discharge position. The breath actuation assembly  100  is biased to remain in this configuration due to the compressive force of the biasing spring  48 . When the dust cover is rotated back toward the horn opening  60 , the cams  120  (see  FIG. 1 ) provided on the dust cover  40  engage the bottom surface of guide  122 , pushing the container holder  24  and container  108  upward along axis  86 . When the dust cover  40  is in its final stowed position covering the horn opening/entrance  60 , the cams  120  have pushed the container holder  24  to the stowed position. In this configuration, the return springs  536  have reset the breath actuation assembly  100  to the locked position, and movement of the container  108  will be retained by the dust cover cams independent of the collapsible linkage. 
         [0067]    The inhaler preferably includes a dose counter for automatically counting the remaining doses left in the container after each discharge of the medicament. The inhaler may be configured with a dose counter having a number of different configurations, including mechanical or electrical counters. The inhaler  20  shown in the accompanying drawings has a dose counter assembly  130  located in a rear side of the main body  42 . The dose counter assembly  130  includes a dose counter casing  610 , an activation lever  620 , a drive gear  630 , a dose counter indicator  640 , a lens  650 , and a dose counter cover  660 . The dose counter assembly  130  may be constructed following the teachings of WO 2012/150427, the disclosure of which is incorporated herein by reference. The activation lever  620  engages in a slot  710  provided in a projection  720  extending upwardly from the container holder  24  (see  FIG. 2A ). 
         [0068]    It will however be understood that an alternative arrangement of dose counter may be used, for example such as that referred to in WO 2005/007226 or WO 2007/066140. Alternatively, the dose counter assembly  130  may be omitted and an inhaler provided without a dose counter assembly. 
         [0069]    The present invention is not limited to the particular embodiments described above and alternative arrangements and suitable materials will be apparent to a reader skilled in the art. Although the description above contains many details, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Therefore, it will be appreciated that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more”. All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims.