Abstract:
The present invention relates to a dispensing apparatus for use in dispensing fluid products in an aerosol form. The invention provides a pump ( 2 ) mounted on a container for storage of the product. The pump comprises a pump body ( 3 ) defining a metering chamber ( 7 ), an inlet ( 25 ) within the container and a stem ( 4 ) for discharging product from the metering chamber and recharging it. Ventilating structures are provided communicating between an exterior of the apparatus and an interior of the container. The ventilating structures comprising a filter ( 40 ) through which ambient air passes, wherein the filter is annular and comprises an axially extending sleeve portion ( 41 ) conformal with an internal surface of the pump body.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to dispensing apparatus for use in dispensing fluid products in an aerosol form. 
     Such a dispensing apparatus typically comprises a dispensing unit engagingly sealed to an upper end of a storage container in which product to be dispensed is held. In order to maintain consistent operation of the dispensing apparatus, as the contents of the storage container are dispensed to an atmosphere during actuation of the apparatus, an air vent is provided to allow air to enter the container in order to equalise the pressures inside and outside the storage container. 
     A problem with ventilating the container in this manner lies in the potential contamination of the product by contaminants in the ambient air which are drawn into the container. This is a particular problem where the product to be dispensed is a pharmaceutical product, a product with perishable ingredients or a product liable to microbial contamination. 
     EP 0 487 412 A1 discloses one solution to this problem. The ventilating means in this apparatus comprises a disc-like annular filter covering a vent opening in a sheath such that ambient air entering the storage container passes through the filter. A problem with the device of EP 0 487 412 A1 is that a different size of filter is required for each type and size of dispensing apparatus that is manufactured. A further problem lies in that the transverse arrangement of the filter across the sheath means that the apparatus is not suitable for use with all storage containers, especially those having narrow openings at their upper ends. A yet further problem with disc-like filters subsists in the difficulty of assembling them with the remainder of the apparatus. Such filters tend to be difficult to handle, especially by automated machines, and easily separated from the remainder of the apparatus. 
     OBJECT OF THE INVENTION 
     It is therefore an object of the present invention to provide a dispensing apparatus having vent means for ventilating the storage container wherein the vent means includes a filter which is suitable for use in all shapes and sizes of storage containers. 
     It is a further object of the present invention to provide a dispensing apparatus having filter means for filtering vented air which is suitable for use with storage containers of all sizes including containers with narrow apertures. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a dispensing apparatus for dispensing a fluid product comprising a pump mounted on a container for storage of the product, the pump comprising a pump body defining a metering chamber, an inlet within the container, and an actuator for discharging product from the metering chamber and recharging it, and ventilating means communicating between an exterior of the apparatus and an interior of the container, ventilating means comprising a filter through which ambient air passes, wherein the filter is annular and comprises an axially extending sleeve portion conformal with an internal surface of the pump body. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG.  1 —shows a cross-sectional view of a dispensing apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention will now be described, by way of example only, with reference to FIG. 1 which shows a cross-sectional side elevation of a dispensing apparatus according to the present invention. In the following description the terms “downwards”, “downwardly”, “upwards” and “upwardly” refer to movement of components of the apparatus when oriented as shown in FIG.  1 . If the apparatus is oriented in a different direction, these terms should be construed accordingly. In addition, the terms “lower” and “upper” denote relative positioning of parts of the apparatus when oriented as shown in FIG.  1 . Again, if the apparatus is oriented in a different direction, these terms should be construed accordingly. The term “fluid” is used generally to denote either the liquid or gaseous phase. 
     FIG. 1 shows one embodiment of dispensing apparatus according to the present invention. The dispensing apparatus  1  comprises a pump, generally designated by reference  2 , mounted on a storage container (not shown) by means of a closure  30  which covers the mouth of the container. The closure  30  has a central substantially cylindrical bore in which is located a collar  50  for positioning the pump relative to the closure  30 . A small ridge may be provided on the inner surface of the bore to hold the collar  50  in position. An upper end of a pump body  3  of the pump  2  extends into and is retainingly engaged within the collar  50  by means of cooperating formations  51   a  and  51   b.    
     The closure  30  may be of plastics material and be designed to be a push-fit over an upper rim of the storage container. The closure  30  may alternatively be a ferrule of deformable metal which is crimped to the upper rim of the container. A gasket  31  of generally annular form is provided within the closure  30  against which the upper rim of the storage container is firmly held to create a fluid tight seal therebetween. The collar  50  is preferably also of a plastics material. 
     The pump  2  comprises, as mentioned above, an elongate pump body  3 . The pump body  3  defines a metering chamber  7 . At a “lower” end of the pump body  3  remote from the closure  30  is an inlet passage  25  which communicates with the metering chamber  7 . An inlet valve  10 ,  11  is provided to open and close the inlet passage  25  during use. The inlet valve  10 ,  11  may, for example, comprise a spherical ball  10  which is movable into and out of sealing contact with a valve seat  11 . Connected to the inlet passage  25  is a dip-tube  12  which extends downwardly into the product contained within the storage container. An end of the dip-tube  12  is retained in the pump body  3  by suitable means, such as a detent formation  13 . 
     The pump  2  further comprises a stem  4 , which is provided in coaxial alignment with the pump body  3 . The stem  4  has a substantially hollow upper part  4   a , which extends from within the pump body  3  so as to protrude out of an uppermost end of the pump body  3  and defines an outlet duct  5 . The stem  4  also has a substantially solid lower part  4   b . A portion of the lower stem part  4   b  is located co-axially within the lower end of the upper stem part  4   a  and is rigidly held in position by means of cooperating formations  24   a  and  24   b . The principal external diameter of that portion of the lower stem part  4   b  located within the upper stem part  4   a  is less than the internal diameter of the portion of the upper stem part  4   a  in which it is located, such that a passage  21  is defined therebetween. The passage  21  communicates with the outlet duct  5  by means of an indented channel  20  in an upper end of the lower stem part  4   b  which spans the join formed by the cooperating formations  24   a  and  24   b . Radially extending ribs  19  extend from the external surface of the lower stem part  4   b  to contact the internal surface of the upper stem part  4   a  in order to prevent relative lateral movement of the upper and lower stem parts  4   a  and  4   b.    
     A sliding seal  16  is disposed around an outer surface of the stem  4 . The seal  16  comprises an annular sleeve portion  16   a  in face to face contact with the stem  4  and flexible extensions  16   b  which extend from the sleeve portion  16   a  radially outwardly into contact with an inner surface  8  of the pump body  3 . The length of the extensions  16   b  is such that they form a fluid tight seal with the pump body  3  even during sliding movement of the seal  16  relative to the pump body  3 . The seal  16  provides the means for centering the stems  4  within the tubular pump body  3 . 
     The stem  4  is also supported in position by the collar  50 , although it does not seal thereagainst. A ventilating flow path is provided between the inner surface of the collar  50  and the stem  4 , and between the inner surface of an upper end of the pump body  3  and the stem  4 . 
     Apertures  57  are provided at an upper end of the pump body  3  to allow fluid communication between the interior of the pump body  3  and the storage container via one or more gaps  56  between the external surface of the pump body  3  and the internal surface of the collar  50 . The ventilating path therefore extends from the interior of the storage container to atmosphere via gap(s)  56 , apertures  57  and the clearance between the upper part  4   a  of the stem  4  and collar  50 . 
     Valve means are provided for controlling the opening and closing of the ventilating portion in the following manner: 
     the upper stem part  4   a  has a radially extending flange  45   a  part way along its length. A distal edge of the flange includes a transverse, upwardly projecting rim  45   b . The collar  50  is provided with an inwardly extending annular extension  52 . In an inoperative position of the apparatus, as shown in FIG. 1, the extension  52  engages with, and forms a fluid tight seal with the flange  45   a  of the upper stem part  4   a . The seal is broken during operation of the apparatus, as described below. Together the extension  52  and flange  45   a  thus form a valve means for controlling opening and closing of the ventilating path linking the contents of the storage container with atmosphere. 
     Further valve means are provided for controlling the product flow path from the metering chamber to the passage  21  inside the stem  4  in the following manner: 
     the lower stem part  4   b  is also provided with a radially extending flange  15   a  with an upwardly turned rim  15   b . A first spring  9  extends between a lower edge  14  of flange  15   a  and a lower part of the pump body  3 , to bias the upper and lower stem parts  4   a  and  4   b  in an upwardly direction wherein the ventilating path is closed by valve means  45   a ,  52 . In this inoperative position a lower end of the annular sleeve portion  16   a  of the sliding seal  16  engages with, and forms a fluid tight seal with the flange  15   a . Together, therefore, the sleeve portion  16   a  and flange  15   a  form a valve means for controlling opening and closing of the outlet from the metering chamber. A second spring  22  extends between an upper end of the sliding seal  16  and a lower edge of the flange  15   a  on the upper stem part  4   a  to bias the sliding seal  16  in a downward direction so that the metering chamber outlet valve means is closed. 
     A filter  40  is incorporated in the dispensing apparatus  1  so as to cover apertures  57 . The filter  40  preferably comprises an annular insert having a sleeve portion  41  and a radial flange  42 . The filter  40  is positioned in the pump body  3  during assembly of the pump  2  so that the sleeve portion  41  lies within an upper end of the pump body  3  and covers the apertures  57 . The flange  42  is of similar external diameter to that of the upper end of the pump body  3 . When fully inserted into the pump body  3  the dependant flange abuts against the upper edge of the pump body  3 . The filter  40  is firmly held in place within the assembled apparatus  1  between the upper edge of the pump body  3  and the collar  50 . The external size and shape of the sleeve portion  41  of the filter is such that the filter  40  forms a “push-fit” with the pump body  3  and an effective seal between the filter  40  and pump body  3  is achieved. Thus any air drawn into the storage container passes along the ventilating path and passes through the filter  40  where harmful and unwanted microbial contaminants are removed from the air. 
     An advantage of the present filter is that the filter  40  may be inserted into the pump body  3  before final assembly of the pump  2 . The pump assembly may then be handled and moved without risk of the filter  40  and pump body  3  separating. This makes overall assembly of the apparatus  1  more straightforward and quicker. The pump assembly is also more suitable for use with automated assembly machinery than conventional “disc-like” filters which are prone to falling out of their seats. 
     The filter  40  may be made from any suitable material, such as plastics or paper. However, the filter has been found to be particularly efficient when manufactured from ultra high molecular weight polyethylene (UMHW-PE). The UMHW-PE is preferably formed by sintering. The UMHW-PE may be formed to have an average pore size of between 7 and 40 microns. 
     Operation of the dispensing apparatus will now be described, starting from the inoperative position shown in FIG. 1 with the metering chamber  7  charged with product. 
     A user of the apparatus depresses the stem  4  by means of an actuator button (not shown) causing the stem  4  to move downwardly. A compressive force is thereby applied to the contents of the metering chamber  7 . At the same time, as the flange  45   a  moves downwardly, the ventilating path valve means  45   a ,  52  open. Since the inlet valve means  10 ,  11  and outlet valve means  15   b ,  16   a  are closed and the contents of the metering chamber  7  are virtually incompressible, further downward movement of the stem  4  causes the sliding seal  16  to move relative to the upper part  4   a  and lower part  4   b  of the stem  4  to accommodate movement of the product within the metering chamber  7 . The movement of the sliding seal  16  opens the outlet valve means  15   b ,  16   a . At this point, the now pressurised contents of the metering chamber  7  are dispensed to atmosphere via the outlet valve means  15   b ,  16   a , passage  21 , indented channel  20  and outlet duct  5 . As the contents of the metering chamber  7  are discharged, the pressure therein decreases and the sliding seal  16  moves back downwardly relative to the upper part  4   a  and lower part  4   b  of the stem  4  under the biasing force of the second spring  22  to close the outlet valve  15   b ,  16   a.    
     When the user releases the stem  4 , it returns upwardly towards the inoperative position of FIG. 1 under the biasing force of first spring  9 . This results in a reduction of pressure within the metering chamber  7  causing product to be drawn up through dip-tube  12  via inlet passage  25  to unseat ball  10  from valve seat  11  to open the inlet valve means  10 ,  11  and re-charge the metering chamber  7 . At the same time, reduction of pressure within the storage container due to removal of a quantity of product therefrom causes ambient air to be drawn into the storage container via the clearance between the stem upper part  4   a  and the collar  50 , ventilating path valve means  45   a ,  52  and clearance  56 .