Abstract:
A delivery device for delivering a metered amount of substance on each actuation thereof that includes a delivery unit operable to deliver a metered amount of substance, wherein the delivering unit includes a metering cavity in fluid communication with a reservoir for storing substance, and a piston member reciprocatingly movably disposed in the metering cavity along a piston axis, the piston member being movable in a first direction to a first, primed position to draw substance into the metering cavity and thereby prime the delivery unit, and a second direction, opposite to the first direction, to a second, delivered position to meter and deliver a metered amount of substance from the metering cavity; and an actuation mechanism actuatable by a user to operate the delivery unit, the actuation mechanism that includes comprising an actuator member to which a user applies an actuation force.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a delivery device for delivering substance on each actuation thereof, and particularly, but not exclusively, a manually-actuatable delivery device for delivering a metered amount of substance on each actuation thereof.  
       BACKGROUND OF THE INVENTION  
       [0002]     Delivery devices which provide for the metering of substance are known in the art. As an example, in the medical field, the use of metered dose inhalers (MDIs) is well established. In an MDI, substance is contained under pressure in a canister having an open end closed by a valve mechanism. The valve mechanism has a valve body which defines a metering chamber of fixed volume and a valve stem which is movable between filling and discharging positions. In the filling position, the valve stem places the metering chamber in fluid communication with the content of the canister, but isolates the metering chamber from the external environment. In the discharge position, the valve stem places the metering chamber in fluid communication with the external environment, but isolates the metering chamber from the content of the canister. In this way, a metered volume of substance is sequentially transferred to the metering chamber and then discharged to the external environment for inhalation by a user.  
         [0003]     The present invention aims to provide an improved delivery device for delivering a metered amount of substance on each actuation thereof, and in particular a manually-actuatable delivery device for delivering a metered amount of substance on each actuation thereof.  
       SUMMARY OF THE INVENTION  
       [0004]     In one aspect the present invention provides a delivery device for delivering a metered amount of substance on each actuation thereof, comprising: a delivery unit operable to deliver a metered amount of substance, the delivery unit including a piston member which, in a reciprocating movement, primes, meters and delivers a metered amount of substance; and an actuation mechanism actuatable by a user to operate the delivery unit, the actuation mechanism comprising an actuator member to which a user applies an actuation force in substantially a single direction, and being configured to cause the reciprocating movement of the piston member on application of the actuation force.  
         [0005]     In one embodiment the delivery unit comprises a metering cavity in fluid communication with a reservoir for storing substance, and the piston member is reciprocatingly movably disposed in the metering cavity along a piston axis, the piston member being movable in a first direction to a first, primed position to draw substance into the metering cavity and thereby prime the delivery unit, and a second direction, opposite to the first direction, to a second, delivered position to meter and deliver a metered amount of substance from the metering cavity.  
         [0006]     Preferably, the actuation mechanism further comprises a gear assembly which is operably coupled to the piston member and the actuator member such as to effect the reciprocating movement of the piston member on application of the actuation force to the actuator member.  
         [0007]     More preferably, the gear assembly comprises a first, drive gear which is rotatable about a pivot and driven by actuation of the actuator member, and a second, driven gear which is rotatable about a pivot, driven by the drive gear and operably coupled to the piston member.  
         [0008]     In one embodiment the actuation mechanism further comprises a drive member which operably couples the piston member and the driven gear.  
         [0009]     Preferably, the drive member is pivotally mounted about a pivot such as to be reciprocatingly pivoted by the driven gear.  
         [0010]     In one embodiment the drive member is configured such that the piston member is moved at a greater speed in the first direction during a delivery stroke in which substance is delivered from the metering cavity than in the second direction during a priming stroke over a length equal to the delivery stroke in which substance is drawn into the metering cavity.  
         [0011]     Preferably, the pivot of the drive member is located in a position offset from an axis extending through the pivot of the driven gear and orthogonal to the piston axis.  
         [0012]     Preferably, the driven gear includes a drive pin on a face thereof which engages the drive member.  
         [0013]     In one embodiment the drive gear includes n lugs on a face thereof, the lugs being equi-angularly spaced and having an angular spacing of 360/n degrees, and the actuator member is configured to rotate the drive gear through 360/n degrees on each actuation thereof.  
         [0014]     Preferably, the driven gear has a diameter of 1/n of that of the drive gear such that, for each actuation of the actuator member, the driven gear is rotated through 360 degrees.  
         [0015]     In one embodiment the metering cavity includes a peripheral wall and the piston member includes a piston which is a sealing fit with the peripheral wall of the metering cavity, the piston having a pressure face for acting on the substance.  
         [0016]     Preferably, the peripheral wall of the metering cavity includes a transfer port, the transfer port being located at a position between the positions of the pressure face of the piston when the piston member is in the primed and delivered positions, and providing for the transfer of substance from the metering cavity to the reservoir with movement of the piston member in the second direction until closed by the piston.  
         [0017]     In one embodiment, prior to actuation of the actuator member, the piston member is located such as to close the transfer port.  
         [0018]     Preferably, prior to actuation of the actuator member, the piston member is located such as to close the metering cavity from an external environment.  
         [0019]     Preferably, the device further comprises: a storage unit including a reservoir for storing substance in fluid communication with the delivery unit.  
         [0020]     Preferably, the device further comprises: an outlet unit in fluid communication with the delivery unit from which substance is delivered.  
         [0021]     More preferably, the outlet unit comprises a spray nozzle.  
         [0022]     In another aspect the present invention provides a delivery device for delivering a metered amount of substance on each actuation thereof, comprising: a delivery unit operable to deliver a metered amount of substance, wherein the delivery unit comprises a metering cavity in fluid communication with a reservoir for storing substance, and a piston member reciprocatingly movably disposed in the metering cavity along a piston axis, the piston member being movable in a first direction to a first, primed position to draw substance into the metering cavity and thereby prime the delivery unit, and a second direction, opposite to the first direction, to a second, delivered position to meter and deliver a metered amount of substance from the metering cavity; and an actuation mechanism actuatable by a user to operate the delivery unit, the actuation mechanism comprising an actuator member to which a user applies an actuation force, and being configured to effect the reciprocating movement of the piston member on application of the actuation force, with the piston member being moved at a greater speed in the first direction during a delivery stroke in which substance is delivered from the metering cavity than in the second direction during a priming stroke over a length equal to the delivery stroke in which substance is drawn into the metering cavity.  
         [0023]     Preferably, the actuator member is configured such that a user applies the actuation force in substantially a single direction.  
         [0024]     In one embodiment the actuation mechanism further comprises a gear assembly which is operably coupled to the piston member and the actuator member such as to effect the reciprocating movement of the piston member on application of the actuation force to the actuator member.  
         [0025]     Preferably, the gear assembly comprises a first, drive gear which is rotatable about a pivot and driven by actuation of the actuator member, and a second, driven gear which is rotatable about a pivot, driven by the drive gear and operably coupled to the piston member.  
         [0026]     In one embodiment the actuation mechanism further comprises a drive member which operably couples the piston member and the driven gear.  
         [0027]     Preferably, the drive member is pivotally mounted about a pivot such as to be reciprocatingly pivoted by the driven gear.  
         [0028]     In one embodiment the pivot of the drive member is located in a position offset from an axis extending through the pivot of the driven gear and orthogonal to the piston axis.  
         [0029]     Preferably, the driven gear includes a drive pin on a face thereof which engages the drive member.  
         [0030]     In one embodiment the drive gear includes n lugs on a face thereof, the lugs being equi-angularly spaced and having an angular spacing of 360/n degrees, and the actuator member is configured to rotate the drive gear through 360/n degrees on each actuation thereof.  
         [0031]     Preferably, the driven gear has a diameter of 1/n of that of the drive gear such that, for each actuation of the actuator member, the driven gear is rotated through 360 degrees.  
         [0032]     In one embodiment the metering cavity includes a peripheral wall and the piston member includes a piston which is a sealing fit with the peripheral wall of the metering cavity, the piston having a pressure face for acting on the substance.  
         [0033]     Preferably, the peripheral wall of the metering cavity includes a transfer port, the transfer port being located at a position between the positions of the pressure face of the piston when the piston member is in the primed and delivered positions, and providing for the transfer of substance from the metering cavity to the reservoir with movement of the piston member in the second direction until closed by the piston.  
         [0034]     In one embodiment, prior to actuation of the actuator member, the piston member is located such as to close the transfer port.  
         [0035]     Preferably, prior to actuation of the actuator member, the piston member is located such as to close the metering cavity from an external environment.  
         [0036]     Preferably, the device further comprises: a storage unit including a reservoir for storing substance in fluid communication with the delivery unit.  
         [0037]     Preferably, the device further comprises: an outlet unit in fluid communication with the delivery unit from which substance is delivered.  
         [0038]     More preferably, the outlet unit comprises a spray nozzle.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0039]     A preferred embodiment of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which:  
         [0040]      FIG. 1  illustrates a part-sectional elevational view of a delivery device in accordance with a preferred embodiment of the present invention; and  
         [0041]     FIGS.  2  to  11  illustrate part-sectional elevational views of the delivery device of  FIG. 1  in various operative states in a single actuation operation. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0042]     The delivery device which will now be described with reference to the accompanying Figures of drawings implements the basic principle of operation for dispensing a metered volume of a fluid disclosed in Applicant&#39;s co-pending International patent application Nos. PCT/EP03/08646 and PCT/EP03/08647, the entire contents of each of which are incorporated herein by reference.  
         [0043]     The delivery device comprises a storage unit  3  for storing a fluid substance, in this embodiment a liquid containing a medicament in suspension or solution, which is to be delivered by the device, an outlet unit  5  from which substance is delivered, a delivery unit  7  which is in fluid communication with the storage unit  3  and the outlet unit  5  and operable to meter a predetermined volume of substance from the storage unit  3  to the outlet unit  5  on operation thereof, and a manually-actuatable actuation mechanism  9  which is coupled to the delivery unit  7  such as to provide for operation of the same on actuation of the actuation mechanism  9 .  
         [0044]     In this embodiment the storage unit  3  comprises a body  11  which includes a storage cavity  15 , which storage cavity  15  has a peripheral wall  16  and a closed end  17  including a transfer port  18 , and a transfer channel  19  which is fluidly connected to the transfer port  18  in the closed end  17  of the storage cavity  15 , and a sealing member  21  which is slideably disposed in the storage cavity  15  such as to be a sealing fit with the peripheral wall  16  thereof and define a reservoir  23  containing substance. The sealing member  21 , in being a free sliding fit with the peripheral wall  16  of the storage cavity  15 , advances with each withdrawal of substance from the reservoir  23  so as to provide that the reservoir  23  contains only substance, and, more particularly, that substance is always present at the transfer port  18  in the closed end  17  of the storage cavity  15 . The body  11  also includes a guide stop  22  which acts as a guide for a drive link  63 , as will be described in more detail hereinbelow.  
         [0045]     In this embodiment the outlet unit  5  is a spray nozzle which comprises a spray head  25  which includes a frusto-conical outlet surface  27  having a plurality of outlet ports  29  disposed thereabout from which substance is delivered on actuation of the delivery unit  7  and an outlet channel  30  which is fluidly connected to the outlet ports  29 , and a resilient, annular skirt  31  which is disposed about the frusto-conical outlet surface  27  of the spray head  25 . The skirt  31  is configured such as normally to close the delivery ports  29  from atmosphere and thereby seal the contained substance from atmosphere, and be deflected outwardly by the pressure of substance when driven through the delivery ports  29  on actuation of the delivery unit  7 , with the substance being delivered as a spray from the spray head  25 .  FIG. 1  illustrates the skirt  31  in the normal state, where the outlet ports  29  in the spray head  25  are closed.  FIG. 9  illustrates the skirt  31  in the deflected state, where substance delivered from the outlet ports  29  in the spray head  25  biases the skirt  31  outwardly and provides a spray.  
         [0046]     The spray nozzle in this embodiment is configured as a nasal nozzle inasmuch as it is sized and shaped for insertion into a nostril of a human being.  
         [0047]     In this embodiment the delivery unit  7  comprises a body  33  which includes a cylindrical metering cavity  35 , which metering cavity  35  has a peripheral wall  36  and a closed end  37  and includes a first, transfer port  39  in the peripheral wall  36  which is fluidly connected to the transfer channel  19  in the body  11  of the storage unit  3  and a second, outlet port  40  in the closed end  37  which is fluidly connected to the outlet channel  30  in the spray head  25  of the outlet unit  5 , and a piston member  43  which is slideably disposed in the metering cavity  35 .  
         [0048]     The piston member  43  comprises a piston  45  which is slideably disposed in the metering cavity  35  and a sealing fit with the peripheral wall  36  of the metering cavity  35  such as to define a metering chamber  49  ahead thereof into which substance is drawn from the reservoir  23  of the storage unit  3  on withdrawal of the piston  45  in a priming stroke, and which meters a predetermined volume of substance to the outlet unit  5  on insertion of the piston  45  in a delivery stroke, which substance, as described hereinabove, is in this embodiment delivered as a spray from the spray head  25  of the outlet unit  5 .  
         [0049]     In the priming stroke, that is, on the withdrawal of the piston  45 , substance is drawn into the metering chamber  49  through the transfer channel  19  from the reservoir  23  when the piston  45  clears the transfer port  39  in the peripheral wall  36  of the metering cavity  35 , with the length of the priming stroke being such as to provide that the amount of substance drawn into the metering chamber  49  exceeds that to be metered to the outlet unit  5 . As will become more apparent hereinbelow, in drawing an amount of substance into the metering chamber  49  which exceeds that to be metered, the metering of the required predetermined amount of substance is ensured.  
         [0050]     In the delivery stroke, that is, on the insertion of the piston  45  into the metering cavity  35 , the piston  45  first acts to drive substance, which represents excess substance, from the metering chamber  49  through the transfer channel  19  into the reservoir  23 , as illustrated in  FIG. 7 , with substance being driven through the transfer channel  19  in preference to the outlet channel  30  owing to the reduced flow resistance thereat. This return of excess substance to the reservoir  23  continues until the transfer port  39  in the peripheral wall  36  of the metering cavity  35  is closed by the piston  45 , as illustrated in  FIG. 8 . Following closure of the transfer port  39 , the piston  45  acts to drive the substance remaining in the metering chamber  49 , which represents the required predetermined volume of substance to be metered, to the outlet unit  5 . With this configuration, the axial position of the transfer port  39  in relation to the length of the delivery stroke of the piston  45  therebeyond determines the volume of substance metered by the delivery unit  7 .  
         [0051]     The piston member  43  further comprises a drive rod  50  which is connected to the piston  45  for driving the same, and the drive rod  50  includes a drive pin  51  which, as will be described in more detail hereinbelow, is engaged by a drive member  55  to drive the piston member  43 .  
         [0052]     In this embodiment the actuation mechanism  9  comprises an actuator member  53  which is manually operated by a user to actuate the delivery device, a drive member  55  which is operably coupled to the drive pin  51  on the drive rod  50  of the piston member  43  to drive the piston member  43 , and a gear assembly  57  which is operably coupled to the drive member  55  such as to reciprocatingly drive the piston member  43  in the delivery and priming strokes on operation of the actuator member  53  by the user.  
         [0053]     The actuator member  53  comprises an actuator button  59  which is pivoted about a pivot  60  to the body  11  of the storage unit  3  such as to be movable between a first, rest position, as illustrated in  FIG. 1 , which is prior to operation, and a second, actuated position, as illustrated in  FIG. 10 , which is following operation by the user having applied the actuation force F to the actuator button  59 , a drive link  63  which is pivotally coupled about a pivot  64  to the actuator button  59  such as to be driven by the actuator button  59  on operation of the same, a first biasing element  65  which acts to bias the drive link  63  towards the guide stop  22  on the body  11  of the storage unit  3 , and a second biasing element  67  which acts to bias the actuator button  59  towards the rest position such as to return the actuator button  59  to the rest position on the user releasing the actuator button  59 .  
         [0054]     In this embodiment the drive link  63  includes a recess  69  at one, the forward, end thereof for engaging one of a plurality of lugs  76  on a drive gear  71  of the gear assembly  57 , as will be described in more detail hereinbelow. As will be further described in more detail hereinbelow, on depressing the actuator button  59  through the application of the actuation force F, the drive link  63 , which is guided by the guide stop  22  on the body  11  of the storage unit  3 , is driven forward and engages one of the lugs  76  on a drive gear  71  of the gear assembly  57 .  
         [0055]     In this embodiment the gear assembly  57  comprises a first, drive gear  71  which is mounted about a pivot  73  to the body  11  of the storage unit  3  and driven by operation of the actuator member  53 , and a second, driven gear  74  which is mounted about a pivot  75  to the body  11  of the storage unit  3  and engages the drive gear  71  such as to be rotated thereby on rotation of the drive gear  71 .  
         [0056]     The drive gear  71  includes a plurality of equi-angularly arranged lugs  76  which are disposed to one face thereof and configured to be engaged by the drive link  63 . In this embodiment the drive gear  71  includes three lugs  76   a,    76   b,    76   c,  each having an angular spacing a of 120 degrees about the pivot  73  thereof. With this configuration, by configuring the actuator member  53  such as to rotate the drive gear  71  through the angular spacing a between respective ones of the lugs  76   a,    76   b,    76   c,  in this embodiment 120 degrees, the drive gear  71  is rotated through the same angle, which corresponds to the angular spacing a of adjacent lugs  76   a,    76   b,    76   c,  on each operation of the actuator member  53 . In other embodiments the drive gear  71  could include any number of lugs  76 , where those lugs  76  are equi-angularly arranged, with the angular spacing a being 360/n degrees, where n is the number of lugs  76 . For example, where the drive gear  71  includes four lugs  76 , the lugs  76  would be each angularly spaced by 90 degrees.  
         [0057]     In this embodiment the driven gear  74  has a diameter which is one-third that of the diameter of the drive gear  71  such that the driven gear  74  is rotated through one complete revolution on rotation of the drive gear  71  through 120 degrees, this being the angular spacing a between adjacent lugs  76   a,    76   b,    76   c  on the drive gear  71 . In other embodiments, where the drive gear  71  has n lugs  76 , the driven gear  74  is sized to have a diameter which is 1/n th of the diameter of the drive gear  71 . The driven gear  74  includes a single drive pin  79  which is disposed to one face thereof. The drive member  55  is pivotally coupled at one end thereof about a pivot  81 , and includes a first slot  83  at the other end thereof in which the drive pin  51  on the drive rod  50  of the piston member  43  is captively disposed, and a second slot  85  at a location between the pivot  81  and the first slot  83  in which the drive pin  79  on the driven gear  74  is captively disposed. With this configuration, rotation of the driven gear  74  causes reciprocating angular rotation of the drive member  55 , which in turn effects a reciprocating movement of the piston member  43 . By configuring the diameter of the circle defined by rotation of the drive pin  79  on the driven gear  74 , the location of the pivot  81  of the drive member  55  in relation both to the pivot  75  of the driven gear  74  and the drive pin  51  on the drive rod  50  of the drive member  43 , both the combined length of the delivery and priming strokes and the relative lengths of phases of the delivery and priming strokes can be configured. In this way, the relative speeds of the delivery and priming strokes can be different, and in particular the speed of the piston  45  can be configured to be quicker in the delivery phase of the delivery stroke during which substance is delivered from the outlet port  40  in the closed end  37  of the metering cavity  35  than the priming stroke. The speed of the piston  45  is advantageously rapid in the delivery phase of the delivery stroke in order to develop the high pressure necessary to generate a spray from the outlet unit  5 , and advantageously slower in the priming stroke in order to allow for the effective transfer of substance from the reservoir  23  of the storage unit  3  to the metering chamber  49  of the delivery unit  7 . In this embodiment the configuration is such that the delivery phase, which corresponds to the movement of the piston  45  from the position in which the transfer aperture  39  in the peripheral wall  36  of the metering cavity  35  is closed by the piston  45 , as illustrated in  FIG. 8 , to the fully-advanced position of the piston  45 , as illustrated in  FIG. 10 , corresponds to 5/32 of a revolution of the driven gear  74 , whereas the priming phase, which corresponds to the movement of the piston  45  from the position in which the transfer aperture  39  in the peripheral wall  36  of the metering cavity  35  is open, as illustrated in  FIG. 4 , to the fully-retracted position of the piston  45 , as illustrated in  FIG. 6 , corresponds to ⅜ of a revolution of the driven gear  74 , where the speed of rotation of the driven gear  74  is substantially uniform for each revolution thereof corresponding to a single actuation of the actuator button  59  of the actuator member  53 .  
         [0058]     Operation of the delivery device will now be described hereinbelow with reference to FIGS.  2  to  11  of the accompanying drawings.  
         [0059]     A user first takes the delivery device, and applies an actuation force F to the actuator button  59  of the actuator member  53 . At the outset, the delivery device is in a rest configuration, in which configuration the piston  45  abuts the closed end  37  of the metering cavity  35  and closes both the transfer port  39  in the peripheral wall  36  of the metering cavity  35  and the output port  40  in the closed end  37  of the metering cavity  35 , as illustrated in  FIG. 2 . By so configuring the delivery device in a rest configuration, the metering chamber  49  is kept sterile, enabling the potential use of preservative-free substances.  
         [0060]     In applying an actuation force F to the actuator button  59 , the actuator button  59  is pivoted about the pivot  60  thereof, with the pivoting of the actuator button  59  causing the drive link  63  to be driven forwardly into engagement with one of the lugs  76   a,    76   b,    76   c,  in this embodiment a first lug  76   a,  on the drive gear  71 , as illustrated in  FIG. 2 . In being driven forwardly, the drive link  63  is guided by the guide stop  22  into engagement with the first lug  76   a  on the drive gear  71 , and, where so engaged, the first lug  76   a  on the drive gear  71  is located in the recess  69  in the forward end of the drive link  63 .  
         [0061]     Following engagement of the drive link  63  with the first lug  76   a  on the drive gear  71 , the drive gear  71  is subsequently rotated.  
         [0062]     In a first phase of rotation of the drive gear  71 , as illustrated in  FIG. 3 , the rotation of the drive gear  71  causes rotation of the driven gear  74 , which rotation of the driven gear  74 , through rotation of the drive pin  79  on the driven gear  74 , in turn effects pivoting of the drive member  55  about the pivot  81  thereof in one sense, in this embodiment a clockwise sense as illustrated, which pivoting of the drive member  55 , through engagement with the drive pin  51  on the drive rod  50  of the piston member  43 , acts to withdraw the piston member  43  from the metering cavity  35  of the delivery unit  7 .  FIG. 3  represents the configuration following rotation of the driven gear  74  through ⅛ of a revolution.  
         [0063]     With continued rotation of the driven gear  74 , the piston member  43  is further withdrawn from the metering cavity  35  until such position, as illustrated in  FIG. 4 , at which the piston  45  of the piston member  43  clears the transfer port  39  in the peripheral wall  36  of the metering cavity  35 , and the metering cavity  35  is in fluid communication through the transfer channel  19  with the reservoir  23  of the storage unit  3 .  FIG. 4  represents the configuration following rotation of the driven gear  74  through ¼ of a revolution.  
         [0064]     From this position, as illustrated in  FIG. 5 , the further withdrawal of the piston member  43  causes the piston  45  to draw substance into the metering chamber  49  through the transfer channel  19  from the reservoir  23  of the storage unit  3 . As illustrated, in compensating for the withdrawal of substance from the reservoir  23 , the sealing member  21  is drawn into the storage cavity  15  of the storage unit  3 .  FIG. 5  represents the configuration following rotation of the driven gear  74  through ½ of a revolution.  
         [0065]     This drawing of substance into the metering chamber  49  continues until the piston member  43  reaches the end of the priming stroke, as illustrated in  FIG. 6 . At this position, the metering chamber  49  includes an excess of substance, which thereby ensures the delivery of the required predetermined volume of substance, as described hereinabove.  FIG. 6  represents the configuration following rotation of the driven gear  74  through ⅝ of a revolution. From this it will be appreciated that the delivery stroke of the piston member  43  will be at a greater speed than the priming stroke (noting that during actuation the speed of rotation of the drive gear  71  is constant, or substantially constant).  
         [0066]     With continued operation of the actuator member  53  through application of the actuation force F and the continued rotation of the driven gear  74 , the driven gear  74  acts to pivot the drive member  55  about the pivot  81  thereof in the opposite sense, in this embodiment the counter-clockwise sense as illustrated, which pivoting of the drive member  55 , through the engagement of the drive member  55  and the piston member  43  at the drive pin  51  on the drive rod  50  of the piston member  43 , acts to drive the piston member  43  into the metering cavity  35  of the delivery unit  7 . As illustrated in  FIG. 7 , which represents the configuration following rotation of the driven gear  74  through ¾ of a revolution, the forward movement of the piston member  43 , and hence the piston  45  thereof, causes the piston  45  to drive substance from the metering chamber  49  through the transfer port  39  in the peripheral wall  36  of the metering cavity  35 , and hence the transfer channel  19 , into the reservoir  23  of the storage unit  3 . As described hereinabove, substance is driven through the transfer port  39  in the peripheral wall  36  of the metering cavity  35  instead of the outlet port  40  in the closed end  37  of the metering cavity  35  owing to the lower flow resistance thereat. This flow of substance into the reservoir  23  of the storage unit  3  is accommodated by outward movement of the sealing member  21  in the storage cavity  15  of the storage unit  3 .  
         [0067]     With continued rotation of the driven gear  74  and forward movement of the piston  45  of the piston member  43 , the piston  45  continues to drive substance from the metering chamber  49  through the transfer port  39  in the peripheral wall  36  of the metering cavity  35 , and hence the transfer channel  19 , into the reservoir  23  of the storage unit  3 .  
         [0068]     This transfer of substance continues until the piston member  43  has been moved sufficiently forwardly as to close the transfer port  39  in the peripheral wall  36  of the metering cavity  35 , as illustrated in  FIG. 8 .  FIG. 8  represents the configuration following rotation of the driven gear  74  through 27/32 of a revolution.  
         [0069]     From this position, the further forward movement of the piston member  43  causes the piston  45  thereof to drive substance from the metering chamber  49  through the outlet port  40  in the closed end  37  of the metering cavity  35  to the outlet unit  5 . At this position, the volume of substance in the metering chamber  49  represents the predetermined volume of substance to be metered by the delivery device.  
         [0070]     As illustrated in  FIG. 9 , which represents the configuration following rotation of the driven gear  74  through 29/32 of a revolution, with continued forward movement of the piston member  43 , the piston  45  thereof acts to drive substance from the metering chamber  49  through the outlet port  40  in the closed end  37  of the metering cavity  35  to the outlet unit  5 . The substance delivered to the outlet unit  5  is delivered through the delivery channel  30  of the spray head  25  and from the delivery ports  29  in the delivery surface  27  of the spray head  25 , with the substance delivered from the delivery ports  29  causing the skirt  31  of the spray head  25  to be deflected outwardly by the pressure of substance and the substance being delivered as a spray from the spray head  25 .  
         [0071]     This delivery of substance from the outlet unit  5 , in this embodiment the spray head  25 , continues until the actuator member  53  is fully depressed and the piston member  43  is at the end of the delivery stroke, as illustrated in  FIG. 10 , with the piston  45  of the piston member  43  abutting the closed end  37  of the metering cavity  35  and thereby closing both the transfer port  39  in the peripheral wall  36  of the metering cavity  35  and the outlet port  40  in the closed end  37  of the metering cavity  35 . In this position, the drive gear  71  has been rotated through 120 degrees, with the lugs  76   a,    76   b,    76   c  having been rotated through 120 degrees and adopting the previous positions of adjacent ones of the lugs  76   a,    76   b,    76   c  prior to actuation of the device.  FIG. 10  represents the configuration following rotation of the driven gear  74  through one revolution, and rotation of the drive gear  71  through 120 degrees, that is, ⅓ of a revolution.  
         [0072]     Following actuation of the device, the user then releases the actuator member  53  by removing the actuation force F from the actuator button  59  of the actuator member  53 . On releasing the actuator button  59 , the actuator button  59  is returned to the initial, rest position by the action of the second biasing element  67  of the actuator member  53 , as illustrated in  FIG. 11 . The actuator button  59 , in being returned to the rest position, draws the drive link  63  therewith to the operative position. The drive link  63  is biased by the first biasing element  65  of the actuator member  53  towards the guide stop  22  on the body  11  of the storage unit  3 , and maintained in the operative position by the first biasing element  65  of the actuator member  53 . In this position, the forward end of the drive link  63 , which includes the engagement recess  69 , is positioned to receive a further lug  76   c  on the drive gear  71  of the gear mechanism  57  on subsequent actuation of the actuation mechanism  9 ; this further lug  76   c  being that lug  76   c  adjacent the lug  76   a  engaged by the drive link  63  in the previous actuation of the device.  
         [0073]     Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.  
         [0074]     For example, in the preferred embodiment, the delivery device is configured for nasal administration, but it should be understood that the delivery device finds equal application in other administration routes, for example, oral and topical administration. For instance, the spray nozzle could be configured as an oral nozzle, e.g. a mouthpiece, instead of a nasal nozzle.  
         [0075]     Also, the delivery device can find application in a delivery system where the delivery device delivers a metered amount of substance to another device which operates on the metered amount of substance. One such delivery system could incorporate the delivery device, where utilized simply to deliver a metered amount of substance, and conveying means to which the substance is delivered, where the conveying means conveys the substance to an outlet for delivery to an external environment. In one embodiment the conveying means can provide for a change of state of the substance. For example, the conveying means may include a vibrating element, such as a mesh, which converts a metered volume of liquid to an aerosol, typically a mist. The vibrating element could, for example, be a piezoelectric element or mesh.  
         [0076]     Further, in the preferred embodiment, the delivery device has a medicinal application, with the substance containing a medicament, but it should be understood that the delivery device has many other non-medicinal applications, typically in the area of consumer healthcare, as in the case of toothpaste, sun cream lotion, etc.  
         [0077]     Yet further, in the preferred embodiment, the substance is a liquid, but it should be understood that the substance can be of other kind, for example, as powders, gases, creams, pastes, etc.  
         [0078]     Also, as regards the provision of reference signs in the appended claims, it is to be understood that reference signs are provided only for illustrative purposes and are not intended to confer any limitation to the claimed invention.