Abstract:
A novel metering device ( 1 ) for dispensing a dose of a pressurized fluid is described. A dispensing valve body ( 3 ) is mounted in a fluid-tight manner to the lid ( 4 ) of a pressurized container ( 5 ), which circumvents a valve element ( 9 ). A valve delivery tube ( 10 ) is connected to the valve element ( 9 ). A chamber ( 13 ) surrounds the valve body ( 3 ), in which a piston ( 17 ) is reciprocable between an upper and a lower position, which define the dispensing dose. A clearance is provided between the piston ( 17 ) and the inner wall ( 23 ) of the chamber ( 13 ), such that pressurized fluid can flow into the chamber based on a pressure difference between the container ( 5 ) and the chamber ( 13 ), and the piston ( 17 ) is adapted to seal the valve body ( 3 ) when being in the upper position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in International Patent Application No. PCT/IB2007/050317 filed on Jan. 31, 2007. 
     FIELD OF THE INVENTION 
     The invention is related a metering device for dispensing a dose of pressurized fluid. 
     BACKGROUND OF THE INVENTION 
     Metering devices for dispensing a dose of pressurized fluid are generally known as metered dose valves by which pressurized fluids are dispensed from containers under pressure. Normally the liquid formulations administered by the metering valve include a liquefied gas propellant and are delivered to a patient in an aerosol spray. The dose of the administered formulation should be sufficient to produce the desired physiological response. The proper amount of the formulation must be dispensed to the patient in each successive dose. Thus, any dispensing system must be able to dispense doses of the liquid formulation accurately and reliably to assure the safety and efficacy of the treatment. 
     Such a metered dose valve is e.g. known from WO-A-2004/0022143 that includes a valve stem which is spring biased towards the valve opening. An interior chamber is defined by a spring cage having one or more inlets from an aerosol container. The upper end of the valve stem includes a metering gasket which is sealing a metering chamber if in the activated position. In the activated position transverse side holes in a longitudinal discharge passageway of the valve stem are discharging in the metering chamber, so that the metered dose of the formulation can be dispensed. 
     The volume of liquid dispensed by such metered dose valves is typically in the range of 70 to 140 microliters for each actuation. However, for certain applications, like applying a liquid spray to the back of the throat in order to prevent snoring, a larger quantity of the formulation is needed, e.g. around 1.5 ml for each actuation. Such large quantities cannot be dispensed by the known metered dose valves. 
     Further, the above mentioned metered dose valves are developed for aerosol containers. Since the environmental regulations require that the use of aerosols should be largely reduced, or even should be completely prevented, it is an object of the present invention to provide a metering device which can be used without an environmental problematic aerosol as propellant for the fluid formulation to be administered to a patient. 
     It is another object of the present invention to provide a metering device system which is capable of delivering a larger volume of liquid spray for each actuation, compared to currently available metered dose valves or manually operated pump spray systems. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention a metering device for dispensing a dose of pressurized fluid from a pressurized container is provided, which comprises a valve body to be mounted in a fluid-tight manner to the lid of a pressurized container, wherein the valve body has upper and lower openings, and captures a gasket between the lid and the upper opening of the valve body. A delivery tube penetrates through the gasket and supports a valve element, which contacts the gasket to close the delivery tube, and which is movable by the delivery tube away from the gasket to open the delivery tube. The inventive metering device further includes a cylindrical chamber having a cup-like form that is defined by an inner tube that houses at least a lower portion of the valve body, an upper roof extending radially outward from said inner tube, and an outer wall extending downward from said upper roof to a rim that defines a lower opening of the cylindrical chamber, wherein the outer wall is larger than the inner tube, such that said cylindrical chamber includes an annular volume between said inner tube and said outer wall, and a cylindrical volume below said inner tube, the lower opening of the valve body being in fluid communication with said cylindrical chamber via said inner tube. A piston is reciprocable within the cylindrical volume between an upper position and a lower position which upper and lower positions define the dispensing dose. At its upper position the piston seals the lower opening of the valve body from the cylindrical chamber, and at any of its positions the piston partitions the cylindrical volume from the lower opening of the cylindrical chamber. A fluid passage is provided from the container to the cylindrical chamber, such that, independent from the position of the piston within the cylindrical chamber, pressurized fluid can flow into the cylindrical chamber based on a pressure difference between the container and the cylindrical chamber. 
     In a further embodiment of the present invention the liquid passage is provided by a clearance between the piston and the inner wall of the chamber. The liquid passage can also be provided by a hole in the piston. 
     The metering device according to the present invention has the advantage, that with a small amount of different pieces an accurate and efficient metering of a relatively large dose of a liquid formulation, e.g. for snore preventing, is obtained. Further advantages are described in the dependent claims and in the description below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in greater detail, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a metering device incorporated in a container, 
         FIG. 2  shows the metering device in a first position in which the valve is opened, 
         FIG. 3  shows the metering device in a second position in which the metering chamber is emptied and a dose of a medicinal formulation is delivered, 
         FIG. 4  shows the metering device when the metering chamber is emptied, 
         FIG. 5  shows the metering device in a third position in which the valve is closed, 
         FIG. 6  shows the metering device in a fourth position in which the piston returns to its initial position in which the metering chamber is filled with fluid again, 
         FIG. 7  shows a container with the metering device in a perspective view, 
         FIG. 8   a  and  FIG. 8   b  show the mounting part of the cap shroud to the container in two different perspective views, 
         FIG. 9   a  and  FIG. 9   b  show the actuator part of the cap shroud in two different perspective views, 
         FIG. 10   a  and  FIG. 10   b  show the metering chamber in two different perspective views, and 
         FIG. 11   a  and  FIG. 11   b  show the piston in two different perspective views. 
         FIG. 12   a  and  FIG. 12   b  show an alternate design of the piston in two different perspective views. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  a metering device  1  is shown with a dispensing valve  2 , comprising an elongated valve body  3  mounted in a fluid-tight manner to a lid  4  of a pressurized container  5 —in the figures only the upper half of the container  5  is shown. The lid  4  has a cup-like form with an upstanding inner flange  6  and a curled-up border  7 . In the present embodiment the valve body  3  is press-fitted by the lid  4  to form a fluid-tight connection with the container  5 . However, also other types of connection, like welding, snapping, screwing etc. are possible. Between the curled-up border  7  and the upper edge of the valve body  3  a gasket  8  is squeezed. A valve element  9  fixedly connected with a delivery tube  10  is urged against the gasket  8  by means of a coil spring  11 . The valve body  3  is entering in a cylindrical chamber  13 , which circumvents the valve body  3 . This chamber  13  has a cup-like form with an inner tube  14  with a first, upper opening  12 , in which the valve body  3  is mounted by a pressfit connection. The chamber  13  has a second, lower opening  15  which is entering into the container  5  with a pressurized fluid. Within the chamber  13  a cylindrical piston  17  is urged to a lower position by means of a coil spring  18  which is held in the upper roof  19  of the chamber by an inner ring  20 . The cylindrical piston  17  has an upper sealing lip  21  and a lower sealing lip  22 , which lips are pressed towards the inner wall  23  of the chamber  13 . The lower position of the piston  17  is defined a ring-shaped stop element  24 . In the centre of the piston  17  a cylindrical bulge  25  is provided which cooperates with the lower opening  12  of the valve body  3 , i.e. in the upper position the cylindrical bulge  25  seals the lower opening  12 . 
     On the outer edge  26  of the container  5 , viz on the rim part of the lid  4 , a cap shroud  27  is mounted by means of a snap-fit connection, which consists of a lower mounting piece  28  and an upper actuator piece  29  which pieces include a mouth piece or beak  30  with a plate-shaped stop element  31 . As can be readily seen in  FIG. 1  a flexible L-shaped tubular joint  33  is mounted on the delivery tube  10  to connect the delivery nozzle or beak  30  with the valve element  9 . The actuator piece  29  has a hinge part  34  and a handle  35 . The mounting piece  28  has in the region of the beak  30  a channel  36  (see also  FIG. 8   a ). 
     The function of the metering device  1  is as follows: 
     In  FIG. 1  the dispensing valve  2  is closed and the piston  17  is in the lower position urged by the coil spring  18  to the inner ring or stop  20 . In  FIG. 2  the handle  35  is pushed towards the container  5  (see arrow  40 ) so that the actuator piece  29  is tilted and the dispensing valve  2  is opened (see arrow  41 ). Thus, the chamber  13  is in open connection to the nozzle or beak  30  so that a pressure drop results and the fluid which has an overpressure will flow from the chamber  13  to the nozzle  30 , while the force of the overpressure in the container  5  urges the piston  17  upwards until the lower opening  12  of the valve body  3  is closed (see arrow  42  in  FIG. 3 ). The coil spring  18  is designed to have a weak spring force with respect to the overpressure in the container  5 . Thus, the chamber  13  is emptied by a dose of the fluid, which dose is defined by the lower position and the upper position of the piston  17  within the chamber  13 , and is ejected from the nozzle  30  as indicated by arrow  43 . While the piston  17  is closing the lower opening  12  of the valve body  3 , the flow of fluid is automatically stopped ( FIG. 4 ). After delivery of the fluid dose the handle  35  is released and the dispensing valve  2  is closed (see arrow  44  in  FIG. 5 ), whereas the piston  17  is still sealing the opening  12  as indicated by arrow  45 . The upper and lower sealing lips  21  and  22  of the piston  17  are designed such that there will be no perfect sealing, i.e. there is little clearance between the sealing lips  21  and  22  and the inner wall  23  of the chamber  13 , so that due to the overpressure in the container  5  fluid will flow from the container  5  to the chamber  13  as indicated by the arrows  46  in  FIG. 6 . The coil spring  18  will ensure that the piston  17  is pushed completely downwards to the inner ring or stop  20 . Thus, chamber  13  is refilled with fluid until the pressure in the chamber  13  equals the pressure in the container  5 . Thereupon the next dose can be spent by the metering device  1 . 
     Instead of the little clearance between the piston  17  and the inner wall  23  of the chamber  13 , a small hole  60  in the piston  17  can be provided which is provided in axial direction, as shown in  FIGS. 12   a  and  12   b . Dependent from the diameter of the hole  60  the fluid will flow slower or faster into the chamber  13 , so that the refill speed can be determined. Therefore, the metering device  1  can be used only after a specific time period, e.g. approximately 10 sec., so that overdosing can be prevented. 
     All components of the metering device are made of a hard plastic material, preferably in PET or PP. 
     In  FIG. 7  a perspective view on the metering device  1  with a pressurized container  5  is shown. The lower part  50  of the container incorporates a pressure control system as described in WO-A-2005/082744. Especially in  FIGS. 5 and 6  thereof a container with a pressure control device and a further piston is shown, which piston is pushed upwards by a gas with a predetermined excess pressure, such that there is only liquid between the piston and the metering device  1 . In such a system the fluid pressure in the container  5  will be kept at a constant level. Thus, the overpressure on the fluid will cause the fluid to flow into the metering chamber  13 . Therefore the dose as spent by the metering device  1  will remain constant as well. 
     Instead of the additional piston as shown in FIGS. 5 and 6 of WO-A-2005/082744 a dip-tube as shown in FIG. 7 of WO-A-2005/082744 can be provided which enters into the chamber  13  of the metering device  1  and ends at the bottom of the container  5  above the pressure control device. In such a case no liquid passage is provided by the piston  17  of the metering device  1 . 
     In  FIGS. 8   a  and  8   b  the mounting part of the cap shroud is shown in two different perspective views. The channel  36  with a small diameter of about 0.5 mm is provided for dosing the fluid with a predetermined fluid pressure, so that the dose can be entered deep enough into the throat of the patient. As can be seen in  FIG. 8   b  there are further some internal fins  51  for positioning the lower mounting piece  28  properly to the container  5 . 
     In  FIGS. 9   a  and  9   b  the upper actuator piece  29  with the hinge part  34  is shown in two different perspective views. Further at the beginning of channel  36  a cylindrical recess  52  is provided for containing an insert with a small through-hole in order to produce a micro mist. Alternatively, the recess  52  can be provided at the end of the channel  36 , i.e. at the end of the beak  30 , so that the insert can produce a micro mist with a predetermined space angle. 
     In  FIGS. 10   a  and  10   b  the metering chamber  13  is shown in two different perspectives. The inner ring  20  for retaining the coil spring  18  on place and the inner tube  14  are ready visible. 
     In  FIGS. 11   a  and  11   b  the piston  17  with the sealing lips  21  and  22  and the cylindrical bulge  25  is also depicted in perspective view. 
     In  FIGS. 12   a  and  12   b , an alternate design of the piston  17  is depicted in perspective view. 
     It will be appreciated to the skilled person that mounting of the dispensing valve  2  to the container  5  can also be made by welding, snapping or screwing. Further, the design of the piston  17  may be changed in that the seal by the bulge  25  is instead provided by an outside ring partly encompassing the inner tube  14 . 
     Various modifications and alterations to this invention will become apparent to the skilled person without departing from the scope and the spirit of the invention. 
     While the present invention has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this invention may be made without departing from the spirit and scope of the present invention.