Patent Publication Number: US-2010127018-A1

Title: Pump Dispenser and Method of Manufacturing a Pump Dispenser

Description:
This invention relates to improvements in or relating to a dispenser and more particularly, but not exclusively, to improvements in or relating to a manual pump-action dispenser and to a method of manufacturing a pump dispenser. 
     Manual pump-action dispensers are commonly used to provide a means by which fluids can be dispensed from a non-pressurised container. In such dispensers, it is known to have a nozzle arrangement that is adapted to dispense the fluid in the form of a spray or, for certain products, as foam. 
     It is also known to provide a dual pump-action dispenser capable of dispensing two different fluids simultaneously. In certain arrangements, the two fluids are mixed in the nozzle before being dispensed through a common outlet orifice. Alternatively, the fluids may be mixed only when they pass through the outlet or may even be dispensed through separate outlet orifices without being mixed 
     The two fluids may both be liquors or one may be a gas or a mixture of gases such as air. In the latter case, it is known to co-eject air and a liquor in certain applications because the mixture of an air stream with a liquor can be exploited to either break up the spray droplets dispensed from the device in the case of spray nozzle device, or modify the properties of the ejected product, e.g. by causing foaming, in the case of more viscous fluids, such as hair mousses, creams, shaving foams etc. 
     Many known dual pump-action dispensers have two pump chambers, one chamber for each fluid. Means are provided for pressurizing the fluid in each chamber and each chamber has an outlet through which the fluid in the chamber is expelled and an outlet valve arranged so that the fluid is expelled from the chamber only when it reaches a pressure that exceeds the external pressure by a predetermined amount. 
     Known dual pump-action dispensers tend to be complex in design making them relatively expansive to manufacture. This is a major problem in a market that is highly cost sensitive. 
     Accordingly, there is a need to provide an improved dual pump-action dispenser that is simpler is design whilst being reliable and effective in operation. 
     There is also a need to provide an improved method of manufacturing a dual pump-action dispenser that is simpler and more cost effective than known methods. 
     Thus, in accordance with a first aspect of the invention, there is provided a manually actuated pump dispenser comprising a dispenser main body including a first pump chamber for a first fluid and an actuator mounted to the dispenser main body for movement towards and away from the dispenser main body, the dispenser further comprising a flexible wall member extending between the dispenser main body and the actuator to define a second pump chamber between the dispenser main body and the actuator for a second fluid, in which the flexible wall member is attached at one end to one of the actuator and a part of the dispenser main body, the flexible wall member having a distal end comprising a collar which is mounted to the other of the actuator and a part of the dispenser main body to form a seal therewith. 
     By attaching one end of the flexible wall member either to the actuator or a part of the dispenser main body and using a collar on the distal end of the wall member to sealingly mount the flexible wall member to the other of the actuator or a part of the dispenser main body, a second pump chamber can be formed in a simple manner that is easier to manufacture and which therefore incurs reduced manufacturing costs when compared with the known dual pump-action dispensers. 
     In an embodiment, the collar is substantially rigid relative to the flexible wall member. 
     In an embodiment, the flexible wall member is an integral part of said one of the actuator and a part of the dispenser main body. 
     In an embodiment, the one of the actuator and a part of the dispenser main body, the flexible wall member and the collar are all integrally formed as a single component from polymeric materials, the collar and at least part of said one of the actuator and a part of the dispenser main body being formed from a rigid polymeric material and the flexible wall member being formed from a different, flexible polymeric material over moulded onto the collar and said at least part of said one of the actuator and a part of the dispenser main body. 
     In an embodiment, the collar locates in a groove in the other of the actuator and a part of the dispenser main body. 
     In an embodiment, the distal end of the flexible wall member extends along one side of the collar and is compressed against a face of groove to form a seal. 
     In an embodiment, the distal end of the flexible wall member has a region of increased thickness which is compressed against a face of the groove to form a seal. 
     In an embodiment, the collar is welded to the other of the actuator and a part of the dispenser main body. 
     In an embodiment, the dispenser main body comprises a base part and an intermediate part mounted together to define the first pump chamber between themselves, the flexible wall member extending between the actuator and the intermediate part. 
     In an embodiment, the intermediate part comprises a rigid portion and a flexible pump member which defines at least part of the first pump chamber. 
     In an embodiment, the intermediate part is formed from at least two polymeric materials, the rigid portion being formed from a first rigid polymeric material and the flexible pump member being formed from a second flexible polymeric material over moulded onto the rigid portion. 
     In an embodiment, the flexible wall member is integral with the intermediate part, the rigid portion of the intermediate part and the collar being formed from a first rigid polymeric material, the flexible pump member and the flexible wall means being formed from one or more flexible polymeric materials over moulded onto the rigid portion and collar. 
     In an embodiment, the actuator comprises a surface and the groove is formed between two wall members which project from the surface towards the intermediate part. 
     In an embodiment, the flexible wall member is an integral part of the actuator. 
     In an embodiment, at least part of the actuator and the collar are formed from a first rigid polymeric material and the flexible wall member is formed from a flexible polymeric material over moulded onto said at least a part of the actuator and the collar. 
     In an embodiment, the dispenser further comprises outlet valve means for controlling the release of fluid from the first and second pump chambers when the dispenser is actuated in use, the outlet valve means being configured to open and allow fluid to exit the first and second chambers to be dispensed only when the pressure of the fluid inside each of the chambers is higher than the atmospheric pressure surrounding the dispenser by a minimum threshold amount. 
     In an embodiment, the first pump chamber is configured to dispense a liquid from a container and the second pump chamber is adapted to dispense a gas, such as air. 
     In an embodiment, at least part of an outlet passage leading from the pump chambers to a dispenser outlet is defined between the intermediate part and the base part. 
     In an embodiment, the gas and the liquid are mixed prior to the dispenser outlet. In an embodiment, the gas and liquid are mixed in the outlet passage. In an alternative embodiment, the dispenser comprises a common outlet valve for controlling the release of liquid from the first pump chamber and a gas from the second pump chamber and the outlet valve is configured so that the liquid and gas mix in the valve prior to entering the outlet passage. 
     In an embodiment, the dispenser is configured to dispense the liquid and gas mixture as a foam. 
     In an embodiment, the outlet passage comprises a filter support to which a generally planar mesh is fitted to form a filter mesh having two portions extending across the flow path in the outlet passage, the arrangement being such that the liquid and gas mixture passing through the outlet passage is caused to pass through both portions of the mesh. The filter support may be generally V shaped so that the planar mesh when fitted to the support adopts a V type shape. 
     In an embodiment, the dispenser is configured to dispense at least one liquid in the form of an atomised spray. 
     In an embodiment, the dispenser is configured such that movement of the actuator towards the main dispenser body reduces the volume of the second chamber to pressurise a fluid contained therein. 
     In an embodiment, the first pump chamber is defined, at least in part, by means of a movable pump member which is subject to the pressure of the fluid in the second pump chamber, such that an increase of pressure of the fluid in the second chamber results in a corresponding increase of pressure of the fluid in the first chamber. 
     In an embodiment, there is no mechanical contact between the actuator and the movable pump member such that, in use during actuation of the dispenser, pressurisation of the fluid in the first chamber and compression of the first chamber to evacuate the fluid therein occurs only as a result of the pressure applied to the movable pump member by the pressure of the fluid in the second chamber. 
     In an alternative embodiment, the actuator means comprises abutment means configured to contact the movable pump member when the actuator is moved towards the main dispenser body so as to depress the movable pump member to pressurise and eject the fluid from the first pump chamber. 
     In an embodiment, the abutment means is spaced from the movable pump member when the actuator is in a rest position, such that the actuator is able to move towards the main dispenser body by a predetermined amount before the abutment means contacts the movable pump member, the arrangement being such that, in use, the pressure of the gas in the second chamber is increased to a desired level before the abutment means contacts the movable pump member. 
     In an embodiment, the movable pump member comprises the flexible pump member. In which case, the flexible pump member may comprise a resilient dome-like member. 
     In an embodiment, the dispenser main body is adapted to be fitted to a container for a fluid to be dispensed. 
     In an embodiment, the dispenser main body is an integral part of a container for a fluid to be dispensed. 
     In an embodiment, at least part of the collar is positioned outboard of a periphery of the dispenser main body. 
     In an embodiment, the main dispenser body comprises two or more first pump chambers, each of which may be configured to dispense a liquid. 
     In an embodiment, each of the first pump chambers in the main dispenser body are defined, at least in part, by means of a movable pump member which is subject to the pressure of the fluid in the second pump chamber, such that an increase of pressure of the fluid in the second chamber results in a corresponding increase of pressure of the fluid in each of the chambers in the dispenser main body. 
     In an embodiment, the dispenser comprises a trigger adapted to be squeezed by a user to actuate the dispenser. The actuator may be an integral part of the trigger or trigger may be operatively connected with the actuator. 
     In an embodiment, the dispenser comprises a cap which can be depressed by a user to actuate the dispenser. The actuator may be an integral part of the cap or the cap may be operatively connected with the actuator. 
     In accordance with a second aspect of the invention, there is provided a method of manufacturing a manually actuated pump dispenser comprising a dispenser main body including a first pump chamber for a first fluid and an actuator mounted to the dispenser main body for movement towards and away from the dispenser main body, the dispenser further comprising a flexible wall member extending between the dispenser main body and the actuator to define a second pump chamber between the dispenser main body and the actuator for a second fluid, the method comprising: 
     forming a collar integrally at a distal end of the flexible wall member; 
     attaching one end of the flexible wall member to one of the actuator and a part of the dispenser main body; 
     mounting the collar to the other of the actuator and a part of the dispenser main body to form a seal therewith. 
     In an embodiment, the collar is relatively rigid compared with the flexible wall member. 
     In an embodiment, the step of attaching one end of the flexible wall member to one of the actuator and a part of the dispenser main body comprises forming the flexible wall member integrally with said one of the actuator and a part of the dispenser main body. 
     In an embodiment, the method comprises forming said one of the actuator and a part of the dispenser main body, the flexible wall member and the collar as an integral component from polymeric materials using bi-injection techniques in which the collar and at least part of said one of the actuator and a part of the dispenser main body are formed from a rigid polymeric material in one injection moulding stage and the flexible wall member is formed from flexible polymeric material over moulded onto the collar and said at least part of said one of the actuator and a part of the dispenser main body in a further injection moulding stage. 
     In an embodiment, the other of the of the actuator and a part of the dispenser main body comprises a groove and the step of mounting the collar to the other of the actuator and a part of the dispenser main body to form a seal therewith comprises inserting the collar in the groove. 
     In an embodiment, the distal end of the flexible wall member extends along one side of the collar and the step of inserting the collar in the groove comprises inserting the collar so that the flexible wall member is compressed between the collar and a face of groove to form a seal. 
     In an embodiment, the distal end of the flexible wall member has a region of increased thickness which is compressed against the face of the groove to form a seal. 
     In an embodiment, the step of mounting the collar to the other of the actuator and a part of the dispenser main body to form a seal therewith comprises welding the collar to the other of the actuator and a part of the dispenser main body. 
     In an embodiment, the dispenser main body comprises a base part and an intermediate part mounted together to define the first pump chamber between themselves, the flexible wall member extending between the actuator and the intermediate part. 
     In an embodiment, the intermediate part comprises a rigid portion and a flexible pump member which defines at least part of the first pump chamber, the method further comprising forming the intermediate part from at least two polymeric materials using bi-injection techniques in which the rigid portion is formed from a first rigid polymeric material in one injection moulding stage and the flexible pump member is formed from a second flexible polymeric material over moulded onto the rigid portion in a further injection moulding stage. 
     In an embodiment, the flexible wall member is formed integrally with the intermediate part, the method comprising forming the rigid portion of the intermediate part and the collar from a first rigid polymeric material in one injection moulding stage and forming the flexible pump member and the flexible wall member from one or more flexible polymeric materials over moulded onto the rigid portion and collar during one or more further injection moulding stages. 
     In an embodiment, the step of inserting the collar into the groove is carried out using a tool. 
     In accordance with a third aspect of the invention, there is provided a manually actuated pump dispenser comprising dispenser main body including a first pump chamber for a first fluid and an actuator mounted to the dispenser main body for movement towards and away from the dispenser main body, the dispenser further comprising a flexible wall member extending between the dispenser main body and the actuator to define a second pump chamber between the dispenser main body and the actuator for a second fluid, the dispenser further comprising outlet valve means for controlling the release of fluid from the first and second pump chambers when the dispenser is actuated in use, the outlet valve means being configured to open and allow fluid to exit the first and second chambers to be dispensed only when the pressure of the fluid inside each of the chambers is higher than the atmospheric pressure surrounding the dispenser by a minimum threshold amount, in which the first chamber is defined at least in part by means of a movable pump member which is subject to the pressure of the fluid in the second pump chamber, the arrangement being such that movement of the actuator towards the main dispenser body reduces the volume of the second chamber to pressurise a fluid contained therein, which fluid pressure acts on the movable pump member to pressurise the fluid in the first pump chamber. 
     In an embodiment, there is no mechanical contact between the actuator and the movable pump member such that, in use during actuation of the dispenser, pressurisation of the fluid in the first chamber and compression of the first chamber to evacuate the fluid therein occurs only as a result of the pressure applied to the movable pump member by the pressure of the fluid in the second chamber. 
     In an embodiment, the first chamber is configured to receive a liquid from a container and the second pump chamber is configured to receive as gas, such as air. 
     In an embodiment, the actuator comprises abutment means configured to contact the movable pump member when the actuator is moved towards the main dispenser body so as depress the movable pump member to pressurise and eject the fluid from the first pump chamber, in which the abutment means is spaced from the movable pump member when the actuator is in a rest position, such that the actuator is able to move towards the main dispenser body by a predetermined amount before the abutment means contacts the movable pump member, the arrangement being such that, in use, the pressure of the air in the second chamber is increased to a desired level before the abutment means contacts the movable pump member. 
    
    
     
       Several embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a cross sectional view through a dispenser in accordance with a first embodiment of the invention; 
         FIG. 2  is a perspective view of a modified form of the dispenser in  FIG. 1 , in accordance with a second embodiment of the invention; 
         FIG. 3  is a perspective view from above of a base part of the dispenser of  FIG. 2 ; 
         FIG. 4  is a perspective view from below of an intermediate part of the dispenser of  FIG. 2 ; 
         FIG. 5  is a perspective view from above of the intermediate part of  FIG. 4 ; 
         FIG. 6  is a perspective view showing the intermediate part of  FIGS. 4 &amp; 5  mounted to the base part of  FIG. 3 ; 
         FIG. 7  is a perspective view from below of an upper or lid part of the dispenser of  FIG. 2 ; and 
         FIG. 8  is a cross sectional view through a dispenser in accordance with a third embodiment of the invention; and 
         FIG. 9  is a cross sectional view through a dispenser in accordance with a fourth embodiment of the invention. 
     
    
    
     Throughout this specification, relative terms such as upper, upward, lower, and downward and their derivatives relate to the various embodiments of dispensers and their component parts in the orientation shown in the accompanying drawings which, with the exception of  FIGS. 4 &amp; 7 , is the orientation in which they will predominantly be used. It will be appreciated, however, that the dispenser may be used in other orientations and such terms should be construed accordingly. 
     In the following specific description, features that are the same or which perform the same function in the various embodiments are given the same reference numeral but increased by 100 for each successive embodiment. 
     With reference to  FIG. 1 , a dispenser in accordance with a first embodiment of the invention is indicated generally at  10 . The dispenser  10  is arranged to dispense a mixture of a liquor and air as foam. 
     The dispenser  10  comprises three main component parts, a base part  12  and an intermediate part  14 , which together define a dispenser main body, and an upper part or actuator  16 . 
     The base part  12  is moulded from a substantially rigid plastics material such as polypropylene. The base  12  has downwardly depending circular skirt  18  with an internal thread  20 , by means of which the dispenser can be mounted to a correspondingly threaded opening of a container (not shown). An upper surface region of the base  12  includes a dome like concave recess  22  which, in combination with an opposing flexible dome-shaped pump member  24  on the intermediate part  14 , defines a first chamber  28  for dispensing a liquid from the container. The liquid to be dispensed may be a liquor. 
     Depending from the dome-like recess  22  is a circular spigot  30 . The spigot  30  has a through bore  32  which opens into the recess  22  to form an inlet  34  into the chamber  28 . A dip tube  36  is mounted to the lower end of the spigot. In use, when the dispenser is mounted to a container, the dip tube  36  extends down into the container so that substantially all the contents of the container can be dispensed through the dispenser  10  in a known manner. 
     An upper region of the base  12  projects forwardly from the skirt  18  to define together with the intermediate part  14  an outlet orifice  38  and an outlet passage  40  leading from the first chamber  28  to the outlet orifice  38 . The upper surface of the projecting part includes a circular cavity or recess  42  for receiving a plug  44  projecting downwardly from a lower surface of the intermediate part  14  to form an outlet or pre-compression valve  45  for the chamber  28 , as will be described in more detail later. 
     Also provided on the upper surface of the projecting part of the base  12  is a filter support lug or cradle  46 , which co-operates with a corresponding lug or cradle  48  projecting downwardly from the lower surface of the intermediate part  14  to support a filter mesh  50 . The cradles  46 ,  48  are shaped so that a passage is provided through the mesh for fluid expelled from the chamber  28  to pass along on its way to the outlet orifice  38 . 
     The intermediate part  14  has a generally planar main body portion  52  formed from a substantially rigid plastics material such as polypropylene. Positioned over an opening in the main body portion is the flexible pump member  24 . The pump member  24  is made from a flexible polymeric material which may be integrally moulded with the main body portion using a bi-injection moulding process. The flexible pump member  24  can be deflected inwardly from the position shown in  FIG. 1  towards and into the concave recess  22  of the base part to reduce the volume of the chamber  28  when a downward force is applied to it, as indicated by arrow A. In certain applications, the flexible pump member  24  may be resiliently biased toward the position shown in  FIG. 1 . 
     The flexible pump member may be a dome shaped member as shown in  FIG. 1  or it can be any other suitable shape provided it is capable of being deformed inwardly to reduce the volume of the first chamber  28  and is capable of recovering to its initial shape. Thus the flexible pump member may be in the form of a bellows or a diaphragm, for example. 
     One problem with dome-shaped chambers can be that a certain amount of dead space exists within the chamber when an operator compresses it, and for some applications it will be preferable that the dead space is minimised or virtually negligible. To achieve this property, it has been found that flattened domes or other shaped chambers whereby a deformable portion of the chambers can be depressed such that it contacts an opposing wall that defines the chamber and thereby expels all of the contents present therein are generally preferred. 
     Two resilient flap members  54 ,  56  are formed integrally with the flexible pump member  24  to provide an inlet valve for the first chamber  28 . A first flap member  54  is adapted to be received in a recess  22 A, which is formed in the base of the concave recess  22 , so that one side overlies and closes off the inlet  34 . The second flap  56  engages the opposite side of the first flap  54  and helps to hold the first flap in engagement with the inlet to ensure a good seal. The inlet has a lip  58  to further improve the seal. The flap  54  is arranged to close off the inlet  34  at all times, except when the pressure in the chamber  28  falls below a minimum threshold below the pressure of the liquor in the container, at which time the first flap  54  is lifted away from the inlet as liquor is drawn into the chamber  28  through the inlet  34 , the spigot  30  and the dip tube  36 . 
     A rib  60  projects downwardly from the underside of the intermediate part  14  and is received in a corresponding groove or recess  62  formed in the upper surface of the base part  12 . The rib  60  and groove  62  form a seal to prevent fluid leaking from the join between the base part and the intermediate part. The seal extends around the chamber  28  and the outlet passage. It is expected that in most dispenser arrangements, the intermediate part and the base part will be welded together along the line of the seal  60 ,  62  to ensure that no leakage between the parts occur and to hold the parts together in their correct alignment. 
     The upper part or actuator  16  of the dispenser is formed from a rigid plastics material such as polypropylene. The actuator  16  is pivotably mounted to the intermediate part  14  by means of a hinge  64  located towards the forward end of the dispenser close to the outlet orifice  38 . 
     A flexible wall  66  extends between the actuator  16  and the intermediate part  14 . The flexible wall  66  encircles the actuator  16  and defines a second pump chamber  68  between the actuator  16  and the intermediate part  14  within the wall. The flexible wall  66  may be in the form of a bellows as shown in  FIG. 1  or it may be in the form of a smooth but flexible wall portion. The flexible wall  66  will usually be formed integrally with either the actuator  16  or the intermediate part  14 . 
     The second chamber  68  is adapted to dispense air to mix with the liquor dispensed from the first chamber  28 . Thus, an air inlet valve  70  is provided on the intermediate part  14  to permit air to be drawn into the second chamber  68  when the pressure inside the second chamber falls below a minimum threshold level below the atmospheric pressure surrounding the dispenser  10 . The air inlet valve  70  comprises two resilient flap members  72 ,  74  that enclose an air inlet passage  76  (shown in dashed lines) formed through the intermediate part  14  and the base part  12  to the outside of the dispenser. The flap members  72 ,  74  are biased towards each other to a closed position as shown in  FIG. 1 . However, when the pressure in the second chamber drops sufficiently below atmospheric pressure, the flap members  72 ,  74  are forced apart by the pressure of the air in the inlet passage  76  so that air is drawn into the first chamber  68 . 
     An outlet valve (not shown) is provided to enable air to pass from the second chamber  68  into the outlet passage  40  where it mixes with the liquor from the first chamber  28  when the dispenser is actuated, as will be described in more detail later. The outlet valve for the second chamber  68  may be similar in construction to the outlet valve  45  for the first chamber. 
     Two leaf spring members  80  (only one of which is shown) project upwardly from the intermediate part  14  and engage a lower surface of the actuator  16 . The leaf spring members are formed from a rigid plastics material and bias the actuator to the position shown in  FIG. 1 . An outer surface  82  of the actuator  16  acts as an actuator surface to which a user can apply a downward pressure on the actuator  16  as indicated by the arrow B to actuate the dispenser. 
     Operation of the dispenser  16  will now be described. For the purposes of this description, it is assumed that both chambers  28 ,  68  are fully charged so that the second chamber  68  is full of air and the first chamber  28  is full of a liquor to be dispensed from a container to which the dispenser has been fitted. 
     In order to initiate actuation of the dispenser  10 , a user applies a force in the direction of arrow B to the actuator  16 . The force applied by a user pivots the actuator  16  about the hinge  64  to move the actuator towards the intermediate part so reducing the volume of the second chamber and compressing the air inside. As the air in the second chamber  68  is compressed, its pressure is increased and this increased pressure is transmitted through the flexible pump member  24  to the liquor in the first chamber  28 . Although the pressure of the liquor in the first chamber  28  is increased, the flexible pump member  24  does not move significantly to reduce the volume of the first chamber  28  due to the relative incompressibility of the liquor and the resilient bias force of the flexible pump member itself, if any. 
     The increased air pressure in the second chamber tends to force the flap members  72 ,  74  of the air inlet valve  70  closer together to ensure that no air can escape through the air inlet. The outlet valve for the second chamber is firmly closed at this stage so that no air escapes from the second chamber through the outlet. 
     Continued application of force to the actuator  16  further compresses the air in the second chamber  68  raising its pressure and the pressure of the liquor in the first chamber  28  until they reach a predetermined threshold level above atmospheric, at which point the peg  44  of the outlet valve  45  is lifted slightly from its recess  42  to open a path between the peg  44  and the recess  42 . The movement of the peg  44  allows the liquor in the first chamber to pass around the end of the peg and to enter the outlet passage  40 . At the same time, the outlet valve for the second chamber  68  opens so that air from the second chamber  68  is able to pass into the outlet passage  40  so as to mix with the liquor to produce foam. The pressure at which the outlet valves  45  open may be between 0.25 and 3 bars but will generally be towards the lower end of this scale when the dispenser is adapted to dispense foam. Where the dispenser is adapted to dispense fluids in the form of a spray, the outlet valves may be designed to open at a pressure of typically in the range of 3-7 bars but which may be as high as 15 bars or more 
     The user continues to apply a downward force B to the actuator  16 , which causes the actuator to mover closer the intermediate part  14  further compressing the second chamber  68  to continue to expel the air into the outlet passage  40 . Because the outlet valve  45  has now opened, this further movement of the actuator  16  results in the flexible pump member  24  deflecting downwardly to reduce the volume of the first chamber  28  so that the liquor continues to be expelled from first chamber into the outlet passage  40 . Thus the pressurisation of the liquid in the first chamber and the compression of the first chamber to expel the liquid results only from the pressure of the air in the second chamber exerting a force on the flexible pump member to pressurise the liquid and to deflect the pump member inwardly to expel the liquid when the outlet valves open. 
     As the dispensing cycle continues, the foam passes along the outlet passage  40  through the filter mesh  50  from which it emerges as finer foam, it then continues along the outlet passage  40  to the outlet orifice  38  where it is finally dispensed. 
     Dispensing continues until one or both of the chambers are empty. By appropriate selection of the volume of the chambers and the dimensions of the outlets from the chambers, it can be arranged that both chambers will are fully evacuated simultaneously. Alternatively, it can be arranged that the first chamber  28  is evacuated first so that air continues to be dispensed after the liquor has stopped. This can be used to help keep the outlet valves  45  and the outlet passage  40  clean. Once the chambers are fully evacuated, the outlet valves  45  will close. 
     When the user stops applying a force B to the actuator  16 , the actuator  16  is biased upwardly to the rest position shown in  FIG. 1  by the leaf springs  80 . The deformable wall  66  may also be resilient so as to assist the springs  80 . As the actuator  16  moves away from the intermediate part, the volume of the second chamber  68  is increased and the pressure within falls. The air inlet valve  70  is arranged so that it does not open until the air pressure in the second chamber drops by a predetermined amount below the atmospheric pressure surrounding the dispenser. Furthermore, since the outlet valve for the second chamber is closed, no air can be drawn back through the outlet and the air pressure in the second chamber  68  reduces to form a partial vacuum. This partial vacuum acts on the flexible pump member  24  of the intermediate part  14  to draw it upwardly towards the position shown in  FIG. 1 . 
     Upward movement of the flexible pump member  24  increases the volume of the first chamber  28 , reducing the pressure inside the first chamber  28  relative to the pressure of the liquid in the container. The valve flap  54  controlling the inlet  34  to the first chamber is arranged to open at a pressure differential that is less than that at which the air inlet valve  70  opens. Consequently, liquor is drawn into the first chamber  28  through the inlet  34  as the flexible pump member  24  is drawn upwardly by the partial vacuum in the second chamber  68 . The flexible pump member  24  may itself be resiliently biased to aid recovery of the first chamber or some other resilient means may be provided. The air inlet valve  70  is arranged to open only when the first chamber  28  is fully recharged, at which time air can enter the second chamber  68 . 
     It will be noted that in the present embodiment, there are no mechanical links between the actuator  16  and the flexible pump member  24  of the first chamber. As a result, the pressure of the liquid in the first chamber is entirely dependent on the pressure of the air in the second chamber  68 . Depending whether there is any bias force acting to bias the flexible dome  24  to its rest (first) position shown in  FIG. 1 , the pressure of the air and the liquor will be substantially the same at all times whilst they are being dispensed. In any event, the relative pressures between the air and the liquor will remain constant whilst they are being dispensed. 
     Whilst the present embodiment comprises separate outlet valves for the two chambers  28 ,  68  this need not be the case and a common valve may be used to control the release of fluid from both chambers. The outlet valve or valves can be of any suitable type provided they act as one way valves to prevent air from entering the liquid pump chamber and visa versa. The, or each outlet valve may be a check valve of the type disclosed and claimed in International patent application No. PCT/GB2006/001963, the contents of which are hereby incorporated by reference. Where two or more chambers share a common outlet valve, the fluids pumped by those chambers can be arranged to mix in the valve rather than in a chamber downstream of the valve. 
       FIGS. 2 to 7  show a modified version of the dispenser device described above. 
     The dispenser  110  shown in  FIGS. 2 to 7  is essentially the same as the dispenser  10  already described although there are a number of differences in its detailed construction. 
     The dispenser  110  has separate outlet valves for each chamber which are of a similar peg and recess arrangement as the embodiment shown in  FIG. 1 . However, as can be seen from  FIGS. 3 and 4 , in this embodiment, the pegs  144 A,  144 B are formed on the base part  112  and are received in recesses  142 A,  142 B in the intermediate part  114 . The arrangement is such that when the pressure of the air and the liquor reach the predetermined threshold, the intermediate part  114  will be deflected upwardly slightly away from the base part so that a gap will be opened between the pegs and the recesses. This enables the liquor in the first chamber  128  to flow through an outlet passage  147  around the peg  144 A of its respective valve into a circular mixing chamber  190  defined between the base part  112  and the intermediate part  114 . As can be seen in  FIGS. 5 &amp; 6 , a through hole  182  is formed in the base of the recess  142 B which forms part of the outlet valve  145 B for the second chamber  168 . When there is a gap between the peg  144 B and its recess  142 B, air in the second chamber is able to pass though the hole  182  and around the peg  142 B and to enter the circular chamber  190  where it mixes with the liquor. The liquor and the air are arranged to enter the circular chamber  190  tangentially so that they spin. In the present embodiment, the air and the liquor enter chamber so that they spin in opposite directions. This has been found to help in the production of fine foam in the chamber. Where the dispenser is adapted to produce a foam, the outlet chamber will usually comprise a constricted opening or pre-throttle after the mixing chamber  109  which leads into an expansion chamber having an increased width and depth relative to the pre-throttle. 
     As shown in  FIG. 3 , a V shaped filter support cradle  146  is formed on the upper surface of the base part  112  within the outlet passage. A corresponding V shaped filter support cradle  148  is provided on the lower surface of the intermediate part  114 , as can be seen from  FIG. 4 . When the base part  112  and the intermediate part  114  are assembled, a fine mesh filter (not shown) is trapped between the two V shaped cradles  146 ,  148 . This provides for a filter in the outlet passage  140  having two legs with a gap in between. The legs of the cradles have recesses to define a fluid flow passage through the filter. The filter mesh may be a flat mesh that is formed into a V shape when the base  12  and the intermediate part are assembled together. This enables a single mesh to be used to provide two filters. 
     Although a fine mesh filter of the type described has been found to be particularly effective any suitable type of filter can be used in the outlet passage. For example, open celled foam could be used as the filter. Furthermore, the filter can be omitted altogether where the dispenser is configured to dispense one or more liquids as a bolus of liquid or as a spray. The filter may even be omitted in certain embodiments where the dispenser is a foam dispenser. 
     The filter is located in the fluid flow passage  140  just downstream from the circular mixing chamber  190  and is arranged in such a way that liquor leaving the mixing chamber travels through the upstream leg of the filter, into the gap between the legs, where it emerges as foam. The foam then passes through the downstream leg of the filter where it emerges as finer foam. Thereafter, the foams travels straight through the outlet passage  140  to the outlet orifice  134 , which in this embodiment is directed outwardly rather than downwardly. Because the liquor is rotating or spinning when it exits the expansion chamber  190 , some of the liquor may pass through each leg of filter more than once to make the foam even finer. 
     In this embodiment, the intermediate part  114  has a flexible wall portion or skirt  166  formed integrally on its upper surface. The flexible wall portion  166  locates in a groove  192  formed in the lower surface of the actuator  116  to form an air tight seal. 
     The two leaf spring members  180  are formed integrally with the base part  112  and extend through slits  194  in the intermediate part  114  to engage in grooves  196  in the lower surface of the actuator  116 . 
     Operation of the dispenser  110  is essentially the same as described above in relation to the first embodiment 10, with the outlet valves being arranged to open at the same pressure so that the liquor and the air are dispensed at substantially the same pressure. 
     Whilst the embodiments described above are both adapted to dispense a foam, it should be appreciated that they can be adapted to dispense a liquid in the form of a spray by providing one or more fine orifices at the outlet, through which the liquid is forced under pressure to cause the liquid to break up or atomise into droplets. As already noted, in order to generate an atomised spray, the liquid and air will typically be ejected from the pump chambers at a higher pressure, in the region of 3 to 7 bar or more, compared with 0.25 to 3 bar for a foam dispenser. Accordingly, the pre-compression outlet valve or valves for the chambers should be adapted so as to open only when the fluid in the chambers reaches the desired operating pressure. 
     Where the dispenser is adapted to dispense a liquid as an atomised spray, the filter will usually be omitted from the outlet passage. However, one or more internal spray-modifying features adapted to reduce the size of liquid droplets dispensed through the outlet orifice of the dispenser during use may be incorporated into the outlet passage in addition to a final swirl chamber adjacent the outlet orifice. Examples of internal spray modifying features that may be present in the outlet passage include one or more expansion chambers, one or more swirl chambers, one or more internal spray orifices (adapted to generate a spray of fluid flowing through within the outlet passage), and one or more venturi chambers. The inclusion of one or more of the aforementioned features is known to affect the size of the spray droplets produced. It is believed that these features, either alone or in combination, contribute to the atomisation of the droplets generated. These spray-modifying features, and the effect that they impart on the properties of the spray produced, are known in the art and are described in, for example, International Patent Publication Number WO 01/89958, the entire contents of which are incorporated herein by reference. 
     The term “internal spray modifying features” refers to features provided in the outlet passage prior to a final outlet orifice, which may be associated with a final swirl chamber. 
       FIGS. 8 and 9 , illustrate two further embodiments of dispensers in accordance with the invention. 
       FIG. 8  illustrates a foam dispenser  210  having a downwardly directed outlet  238 . The dispenser  210  is generally similar in construction and operation to the first and second embodiments described above, the main difference being in the method of forming the flexible wall between the intermediate part of the dispenser body and the actuator. Details of the outlet valves and the outlet passage have been omitted from  FIG. 8  and reference should be made in this respect to the description above in relation to the first and second embodiments. 
     In this embodiment, the flexible wall  266  is formed integrally with intermediate part  214  using bi-injection moulding techniques. Thus the rigid main body portion  252  of the intermediate part  214  is moulded in first moulding stage from a substantially rigid polymeric material. The flexible pump member  224 , including the valve flaps  254 ,  256 , and the flexible wall  266  are then over moulded onto the rigid main body portion  252  from a flexible, and usually resilient, polymeric material. The flexible pump member  224  and the flexible wall  266  may be made from the same flexible polymeric material or they may be made from different materials depending on the characteristics required for each part. 
     The free end  266 A of the flexible wall  266  is slightly thickened to form a seal member and is over moulded onto a rigid collar  265 . The collar  265  may be made of the same material as the main body portion  252  of the central part and is preferable moulded at the same time as the main body portion during the first moulding stage. With this arrangement, the flexible wall can be over moulded between the main body  252  and the collar  265  during the second injection moulding stage. 
     The under surface of the actuator  216  has a groove formation  267  into which the free end  266 A of the flexible wall  266  and the collar  265  are inserted to firmly attach the flexible wall to the actuator and to form an airtight seal. The groove is formed between a downwardly projecting outer peripheral wall  216 A of the actuator and a small inner wall  269  which projects downwardly from the under surface of the actuator  216  parallel to but spaced from the outer peripheral wall  216 A. 
     The free end  266 A of the flexible wall  266  extends along one side of the rigid collar so as to abut an inner surface of the inner wall  269 . The thickness of the free end  266 A and the collar  265  are selected to ensure that the free end  266 A of the flexible wall is compressed tightly against the inner wall  269  to form a seal when they are inserted into the groove. A small tab  271  projects inwardly from the outer peripheral wall  216 A for location under the collar  265  to hold the collar and the free end of the flexible wall in the groove  267  when they are fully inserted. To assist in inserting the collar and free end of the flexible wall into position in the groove, an outer side face of the collar  265  is angled and this contacts a correspondingly angled surface on the tab  271  so that the free end  266 A of the flexible wall is compressed as the collar  265  is inserted into the groove  267  past the tab. 
     In the arrangement shown in  FIG. 8 , the flexible wall  266  is positioned outboard of the main dispenser body, as defined by the base part  212  and the intermediate part  214 . This enables a tool to be used to push the collar  265  into the groove  267  in the actuator  216  and to hold the component parts of the dispenser stable while this takes place. Such a tool may be automated. 
     The flexible wall  266  completely surrounds the upper surface of the dispenser body to create an air tight chamber  268  between the dispenser body and the actuator  216 . Where the maximum pressure generated in the first pump chamber  218  is relatively low, say up to 3 bar, the mechanical seal created by insertion of the free end  266 A of the flexible wall and collar  265  in the groove  267  is sufficient. However, where higher pressures are to be generated in the first pump chamber  218 , then it may be necessary to weld the collar  265  in the groove  267  to ensure that an adequate seal is produced. Welding is preferably carried out ultrasonically but any suitable method can be used. Preferably, a tool used to insert the collar  265  in the groove will also be used weld the collar  265  to the actuator. Where the collar  265  is to be welded in position, the free end  266 A of the flexible wall  266  may be attached to a lower surface of the collar so that only the collar is inserted into the actuator groove  267 . This helps to prevent the free end of the flexible wall melting during the welding process and adversely affecting the weld. Where the collar  265  is welded in position, the tab  271  which locates under the collar can be omitted. It will also be appreciated that where the collar  265  is to be welded in position, the groove  267  can be omitted altogether or may be reduced in depth so as to act as a guide for positioning the collar. 
     At a forward end region of the dispenser, the distal end of the inner wall  269  contacts an upwardly projecting abutment on the upper surface of the intermediate part  214  to form a fulcrum about which the actuator pivots when a force is applied in the direction of arrow B to actuate the dispenser. The under surface of the actuator  216  has a projection  273  which extends downwardly towards the flexible pump member  224 , which partly defines the second liquid pump chamber  228 . When a user depresses the actuator  216 , the projection  273  contacts the pump member  224  so that the first chamber is compressed mechanically. To ensure that both the air in the second chamber  268  and the liquid in the first chamber  228  are dispensed at the correct pressure, the distal end of the projection  273  is spaced from the pump member  224  when the actuator is at its rest position, as shown in  FIG. 8 . Thus when the actuator is initially depressed, it is able to move towards the intermediate part  214  by a set distance before the projection  273  contacts the pump member  224 . This initial movement compresses the air in the second chamber  268  and the arrangement is such that projection  273  does not come into contact with the pump member  224  to force the liquid out of the second pump chamber  228  until the pressure of the air is increased to its required level. Typically, the air pressure in the second chamber  268  is arranged to be equal to the pressure of the liquid in the first chamber  228  when the outlet valve or valves open but the air pressure may be set to be slightly higher than the pressure of the liquid. In a modified arrangement, the pressure of the air in the second chamber  268  may be relied upon to pressurise the liquid in the first chamber to the point at which the outlet valve or valves open in the manner described above in relation to the first two embodiments. In this case, the projection  273  will only contact the pump member  224  later in the dispensing cycle to ensure that the liquid chamber is fully compressed and all the liquid discharged. 
     Once the actuation force is removed, the flexible wall  266  restores the actuator to its rest position, as shown in  FIG. 8 , drawing a fresh charge of liquid into the second pump chamber  228  and a fresh charge of air into the second chamber  268  in a manner similar to that described above in relation to the first and second embodiments. In this embodiment, there are no resilient leaf spring members which apply a restoring force to the actuator  216  but rather the flexible wall  266  is resiliently deformable and it is the resilience of the flexible wall which generates the necessary restoring force. 
     As shown in  FIG. 9 , the flexible wall  266  comprises a smooth wall member that extends generally vertically over the majority of its length. However, the flexible wall  266  can be any shape provided it can be deformed to allow the second chamber to be compressed and which will reform when the force compressing the chamber is removed. For example, the flexible wall may be in the form of a bellows as in the first two embodiments. Alternatively, the flexible wall may be inclined or it could be formed in a partially dome-like shape. In a yet further alternative, the flexible wall may take the form of a rolling diaphragm. 
     In an alternative arrangement (not shown) the flexible wall  266  and collar  265  can be formed integrally with the actuator  216  rather than the intermediate part  214 . Again a bi-injection process can be used with the actuator  216  and collar  265  being moulded in a first stage from a rigid polymeric material and the flexible wall  266  being over moulded onto the actuator and collar in a second stage from a polymeric material which is flexible relative to the first material. In this arrangement, the collar  265  with the free end  266 A of the flexible wall attached is inserted into a groove formed in the intermediate part  214 . The collar  265  may be inserted into the groove and held in place mechanically or it may be welded in position as discussed above. The groove will usually be formed about the periphery of the intermediate part  214 . 
     By forming the flexible wall member  266  and collar integrally with the intermediate part  214  or actuator  216  using bi-injection moulding techniques means that the dispenser can be produced using only three separate component parts: the base part, the intermediate part and the actuator, which can be assembled automatically. It will be noted in this regard that components which form the inlet and outlet valves for the chambers are all formed integrally with the base part and intermediate part. This arrangement provides for a very simple, yet highly effective dual chamber pump-action dispenser which can be manufactured at relatively low cost. As a result a dual-chamber dispenser in accordance with the invention can be used in place of a single chamber dispenser at little additional cost but providing all the benefits in terms of spray and foam quality that arise from mixing pressurised air with the liquid. 
       FIG. 9  illustrates a dispenser  310  having a flexible wall  366  constructed and attached to the actuator  316  in an identical manner to the dispenser  210  described above. In this embodiment, the dispenser is adapted to generate an atomised spray and has an outlet  338  comprising a very fine spray orifice  375  and a swirl chamber  377 . Details of the outlet valves and the outlet passage have again been omitted and reference should be made in this respect to the description above in relation to the first and second embodiments. 
     It will be noted that the outlet orifice  375  of the dispenser  310  is positioned inwardly of the forward edge of the actuator  316 . This enables the flexible wall and collar  365  to be positioned outboard of the periphery of the dispenser main body so that a tool can be used to insert the collar  365  into the groove in the actuator  316 . This is particularly advantageous where the collar  365  is to be welded in position, as it is essential that the welding tool can access the entire length of the collar  365 . 
     The dispenser  310  is generally constructed and operated in the same manner as the dispenser  210  described above and the comments made in relation to the dispenser  210  and the various alternative arrangements apply equally to the dispenser  310 . 
     Dispensers  10 ,  110  in accordance with the first and second embodiments can be modified to include a flexible wall member constructed and manufactured as described above in relation to the third and fourth embodiments  210 ,  310 . 
     In the embodiments described above, the actuator is pivoted about a forward end of the dispenser. However, dispensers in accordance with the invention can be modified so that the actuator moves in any one of a number of different ways relative to the dispenser main body. For example, the actuator could be formed as part of a trigger mechanism. In this case, the actuator is arranged to pivot about a rear edge, or at a position between the rear edge and the front edge, and a portion of the actuator extends down over the front of the dispenser and container to form a trigger. The trigger is arranged so that a user can grasp the trigger with their fingers and pull the trigger inwardly to actuate the dispenser in a known manner. The trigger portion may have an opening through which the outlet of the dispenser projects when the trigger is pulled. In a further alternative, the actuator may be in the form of a cap which is arranged to be depressed linearly towards the intermediate part when the dispenser is actuated. In this arrangement, the cap may have an opening which aligns with the dispenser outlet when the dispenser is actuated. In either of these variations, the flexible wall can be constructed and attached between the intermediate part (or some other part of the dispenser main body) and the actuator in a manner similar to that described above in relation to the dispensers  210  and  310  shown in  FIGS. 8 and 9 . Regardless of how the actuator is configured to move relative to the dispenser main body, the actuator may have a projection which contacts the flexible pump member or the dispenser may rely on the pressure of the fluid in the second chamber to pressurise the first chamber in the manner described in relation to the first and second embodiments as shown in  FIGS. 1 to 7 . 
     It is not essential that dispenser be arranged so that a user applies pressure or a force directly to the actuator in order to actuate the device. For example, the dispenser may comprise a further actuation means to which a user applies a force and which is operatively connected to the actuator to cause it to move towards the dispenser main body to actuate the dispenser. Thus the dispenser may comprise a separate trigger or cap which is operatively connected to the actuator. In this arrangement, the actuator forms a chamber with the flexible wall member which can be positioned underneath a separate trigger or within an actuating cap. The actuator, flexible wall member and collar may be formed as a separate integral component and the actuator surface may be rigid or flexible. The collar can be welded or otherwise mounted to the dispenser main body or to the trigger or cap or other actuator. In the latter case, a hole or tube is provided in the actuator which connects with a corresponding hole or tube on the dispenser main body to form a fluid connection between the second pump chamber and the outlet valve means and the outlet passage. 
     In the embodiments described herein, the first pump chamber is defined in part by means of a movable pump member in the form of a dome-like flexible pump member. However, the first pump chamber may be defined by any suitable movable pump member. For example the first pump chamber could be defined by means of a piston which is movably mounted in a cylinder in the dispenser main body so that the piston can be moved to reduce the volume of the first chamber. The piston may be moved as a result of the pressure in the second chamber acting on the piston or as a result of a projection on the actuator contacting the piston when the actuator is moved towards the dispenser main body. In this arrangement, a resilient means will be required to restore the piston to the rest position after each actuation. 
     References to a “rigid plastic material” or “rigid polymeric material” are used herein to refer to a plastic or polymeric material that possesses a high degree of rigidity and strength once moulded into the desired form, but which can also be rendered more flexible or resiliently deformable in portions by reducing the thickness of the plastic. Thus, a thinned section of plastic can be provided to form the deformable wall portions that define at least part of the chambers. 
     References to “flexible plastic materials” or “flexible polymeric materials” include plastics or polymeric materials which are inherently flexible/resiliently deformable so as to enable the displacement of at least a portion of the dispenser to facilitate the compression of the chambers. The extent of the flexibility of the plastic may be dependent on the thickness of the plastic in any given area or region. Such “flexible plastic” materials are used, for example, in the preparation of shampoo bottles or shower gel containers. In the fabrication of a dispenser in accordance with the present invention, portions of the dispenser may be formed from thicker sections of plastic to provide the required rigidity to the structure, whereas other portions may be composed of thinner sections of plastic to provide the necessary deformability characteristics. If necessary, a framework of thicker sections, generally known as support ribs, may be present if extra rigidity is required in certain areas. 
     Whereas the invention has been described in relation to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed arrangements but rather is intended to cover various modifications and equivalent constructions included within the spirit and scope of the invention. For example, whilst the preferred embodiments described above are all dispensers in which one chamber is arranged to dispense liquor and the other air, the invention can be equally applied where the dispenser is adapted to dispense two liquors, two gases or a liquor and a gas or mixture of gases other than air. Furthermore, there may be more than one first pump chamber for liquids in the dispenser main body with one or more air chambers provided above the liquid pump chambers so that the dispenser can be adapted to dispense two or more liquids mixed with air, either as a foam or a spray. For example, there may be two first pump chambers in the dispenser main body for pumping two different liquids and a common air chamber above the liquid chambers, with the outlets from all three pump chambers converging in the outlet passage or in a common outlet valve.