Abstract:
A dispenser mechanism  1  for a foamed product comprises a liquid chamber  9  and air chamber  10 , each compressed by a common actuator mechanism  6   a,    6   b , wherein the liquid and air simultaneously enter a foaming chamber  15 . The liquid is forced through a diffuser  18   a  defining a plurality of distributed channels  18   e , each channel  18   e  having a predetermined cross section such that in use the liquid is forced through the channels and enters the foaming chamber as a plurality of jets. The dispenser mechanism  1  provides a particularly advantageous arrangement for producing foam and may be arranged to prevent the foam dripping from an outlet after the end of a dispensing cycle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a National Phase Application and claims the priority of International Application Number PCT/GB2007/050570 filed on Sep. 21, 2007. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a dispenser mechanism for foamed products and particularly, but not exclusively, relates to dispenser mechanisms for wall mounted soap dispensers. 
     2. Description of the Related Art 
     Wall mounted soap dispensers traditionally dispense a liquid soap. However, with liquid soap it is necessary for the viscosity to be high enough that it can be applied to the hands without running off, enabling the soap to cling to the hands while being conveyed from under the dispenser to over the sink. Two problems associated with the high viscosity of liquid soaps is that it is necessary to dispense a relatively large quantity to enable the user to easily spread the soap over the surface of his hands and also this high viscosity tends to result in a large quantity of the soap remaining in the outlet of the dispenser, which subsequently drips onto the surface or the floor below. 
     In an attempt to address the above problems, soap dispensers have been developed which produce foam by mixing air with the liquid soap as it is dispensed. The action of operating the dispenser causes a soap product to be sprayed into a jet of air to produce the foam. The advantage of this is that a large quantity of foam can be produced from a relatively small volume of liquid soap, reducing the amount of liquid a user requires to satisfactorily apply the soap over his hands. This reduces the cost of product required and also the frequency with which the dispenser needs to be refilled. Thus foam dispensers overcome one of the problems identified above associated with traditional liquid soap dispensers. However many foam dispensers still tend to drip as foam accumulated in the nozzles reverts to a liquid causing the nozzle to drip. 
     BRIEF SUMMARY OF THE INVENTION 
     It is desirable that the dispenser mechanism is compact and comprises a minimum of components so that it may be relatively inexpensive and therefore practical to produce a dispenser mechanism which can be sold as part of the refill pack for a dispenser, thus the parts likely to fail are part of the disposable refill and can thus, in the event of a failure, can simply be replaced by replacing the refill pack. 
     It is an object of the present invention to provide an improved dispenser mechanism for foam products. 
     According to a first aspect of the present invention a dispenser mechanism for a foamed product comprises: a liquid chamber arranged to receive a liquid product; an air chamber arranged to receive air; an actuator mechanism; and a foaming chamber, the actuator mechanism comprising a shaft, displacement of which simultaneously reduces the volume of both the liquid and air chambers and forces the air and liquid within the respective chambers to enter the foaming chamber, characterised in that the foaming chamber is formed integrally within the shaft and in that a diffuser is located in the shaft through which the liquid enters the foaming chamber, the diffuser defining a plurality of distributed channels, each channel having a predetermined cross section such that in use the liquid is forced through the channels and enters the foaming chamber as a plurality of jets. 
     The invention permits efficient mixing of the liquid and air in a very compact arrangement. 
     Preferably, the actuator mechanism comprises two pistons on a common shaft, each piston acting on respective one of the liquid and air chambers, for in this way it is possible to have a dispenser mechanism which employs only one single moving part, which reduces costs associated with manufacturer and thus is particularly beneficial if the dispensing mechanism is to be part of a disposable refill pack. 
     Advantageously, a first chamber is in the form of a cylinder in to which a first one of the pistons extends to pressurise the contents of the chamber and wherein the foaming chamber is formed in the shaft, as this can provide a very compact arrangement. 
     Preferably, the actuator mechanism is biased to a rest position where both pistons are withdrawn to their maximum extent from their respective chambers. When in the rest position, the liquid chamber can be sealed, preventing liquid seeping through the dispenser mechanism. 
     It is particularly advantageous if the action of the actuator mechanism returning to its rest position sucks air into the air chamber via an outlet of the dispenser mechanism, causing any foam remaining in the outlet to be sucked back into the air chamber and thus preventing the foam from reverting to a liquid in the outlet and dripping from the outlet. 
     Advantageously, the liquid chamber has a one way valve to permit liquid to enter the chamber when the piston is withdrawn from the chamber, wherein the dispenser mechanism includes a transport cap arranged to prevent accidental operation of the actuator mechanism in transit, the transport cap being arranged to keep the actuator mechanism in a fully depressed position where the piston of the liquid chamber is in contact with the one way valve and maintains it in a closed position. This may be particularly advantageous where the dispensing mechanism is to be sold as part of a disposable refill pack for assembly as a complete unit within a wall mounted housing. This can ensure that pressures applied to the walls of the liquid container, which is normally a non-vented collapsible container, will not cause the liquid within the container to leak out via the dispenser mechanism. 
     The diffuser may have a plurality of recesses about its outer periphery, which recesses define with the inner wall of the shaft said plurality of channels. The recesses can then be formed in the moulding of an upper component of the shaft, on which the diffuser is preferably integrally formed. Alternatively the periphery of the diffuser may be smooth with ridges or recesses formed on the inner wall of the shaft, such when the diffuser is located in the shaft, the diffuser and inner wall of the shaft together define said plurality of distributed channels. 
     As an alternative to the above described embodiments of the diffuser, the diffuser may instead comprise a rigid disc with a plurality of apertures extending there through. 
     Preferably the shaft comprises an upper component and a lower component, each moulded as a single piece, wherein the upper component includes a first piston and the diffuser, the lower component includes a second piston and an outlet passage of the mechanism. The upper component of the shaft may further comprise a retaining disc integrally moulded with the first component, wherein an edge of the retaining disc and an inner wall of the shaft are arranged to engage with each other to lock the upper and lower components together. This enables the shaft to comprise only two components that together form the two pistons, the mixing chamber and the diffuser, with the retainer enabling the two components to be assembled simply by snapping them together. 
     A dispenser mechanism in accordance with the invention is particularly advantageous in manually operated applications, such as soap dispensers. 
     Preferably, the dispenser mechanism further comprises a user interface for receiving a single stroke actuation by a user for dispensing a predetermined quantity of product to the user and a linkage mechanism for transferring, on a full stroke of the dispenser mechanism, any displacement of the user interface to the dispensing mechanism, wherein the linkage mechanism permits the user interface to be operated to the full extent permitted by the interface and transmit only as much of the operation of the interface to be transmitted to the dispenser mechanism as is required to permit the dispenser mechanism to dispense the predetermined amount of product. 
     This mechanism is particularly advantageous for it can be arranged to ensure that any reasonable exertion on the user interface causes the dispenser mechanism to operate fully and thus provide a desired volume of product, while ensuring that any excessive pressure applied to the user interface does not damage the dispenser mechanism. It can also permit a single dispenser case to be used with a range of products and product volumes without modification, or to allow a common dispenser mechanism to be adjusted to provide different product volumes by adjusting the dispenser mechanism stroke length. It also prevents damage to the dispenser mechanism that occurs when the pump mechanism controls the actuation stroke of the dispenser interface. 
     Advantageously, the linkage mechanism comprises a resilient device between the interface and dispenser mechanism, properties of the resilient device being sufficient to fully activate the dispenser mechanism when the interface is sufficiently operated, but which absorbs any further movement of the interface to prevent damage to the dispenser mechanism. 
     The invention is particularly applicable to soap dispensers arranged to permit single handed one stroke operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One embodiment of the present invention will now be described, by way of example only, with reference to the figures, in which like numerals are used throughout to indicate like parts, and in which: 
         FIG. 1  is a cross-section through a dispensing mechanism in accordance with the present invention, with a transport cap in place; 
         FIG. 2   a  is a corresponding cross-section to that of  FIG. 1  but with the transport cap removed; 
         FIG. 2   b  is an enlarged scale view of the section labelled ‘X’ of  FIG. 2 ; 
         FIG. 2   c  an enlarged scale section along the line A-A of  FIG. 2 ; 
         FIG. 2   d  an enlarged scale section along the line B-B of  FIG. 2 ; 
         FIG. 2   e  depicts an alternative embodiment of the invention; 
         FIGS. 3 to 5  are sectional views corresponding to that of  FIG. 2   a , but depicting the dispensing mechanism at various stages of operation; 
         FIG. 6   a  is a side elevation of the dispenser mechanism additionally illustrating a user interface for the dispenser mechanism described with reference to  FIGS. 1 to 8 ; 
         FIG. 6   b  is a front sectional view of the dispenser of  FIG. 6   a ; and 
         FIGS. 7   a ,  7   b ,  8   a ,  8   b ,  9   a ,  9   b ,  10   a  and  10   b , correspond to those of  FIGS. 6   a  and  6   b , but show the dispenser at various stages of operation in the dispensing cycle. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , there is illustrated a dispenser mechanism  1  in accordance with the present invention connected to a disposable collapsible container  2  filled with liquid soap  3 . The container  2  and dispenser mechanism  1  together form a disposable refill pack for wall mounted soap dispensers. 
     The dispenser mechanism of  FIG. 1  is transported attached to the filled container  2  and the dispenser mechanism comprises a transport cap  4 , secured to the housing  5  of the dispenser mechanism. This prevents accidental actuation of the dispenser mechanism prior to installation in a dispenser, or leakage due to compression of the collapsible container  2 . 
     The dispenser mechanism has a shaft  6  comprising an upper component  6   a  and a lower component  6   b , joined together such that in use there is no relative displacement between them. The upper component  6   a  defines a first piston  7  and the lower component  6   b  defines a second piston  8 . 
     The first piston  7 , together with the housing  5 , defines a first chamber  9 , with the second piston  8  defining with the housing  5  a second chamber  10 . 
     In the top of the first chamber  9  there is an opening, in which opening there is located a non-return valve  11 . When open, the non-return valve  11  permits liquid soap  3  to flow from the container  2  to the first chamber  9 . 
     When the transport cap is in place, as shown in  FIG. 1 , the shaft  6  and associated piston  7  and  8  are retained in a fully depressed, (raised), position whereby a pin  12 , extending from the centre of the first piston  7 , engages with the non-return valve  11  to keep it in a closed position, as shown. This ensures that during transit, fluid cannot leak from the container  3  through the dispenser mechanism  1 . 
     Referring now to  FIG. 2   a , a corresponding view to that of  FIG. 1  is shown but with the transport cap  4  removed. When the transport cap is removed and the dispenser mechanism installed in a dispenser (as described below with reference to  FIGS. 6   a  to  10   b ) the mechanism of the dispenser, not shown in  FIG. 2   a , biases flange  13  located towards the bottom of lower component  6   b  of the shaft  6  to the position shown in  FIG. 2   a . In this position rubber O-ring seal  14  seals with the first piston  7  preventing the liquid soap  3  passing between the outer wall of piston  7  and the inner wall of the housing  5 . The O-ring  14  is retained in place by end cap  14   a . Drawing the shaft  6  downwards causes liquid soap  3  to flow into the first chamber  9 . 
     As most clearly seen in  FIG. 2   b , the upper component  6   a  of shaft  6  and the lower component  6   b  of shaft  6  define, at the lowermost portion of the component  6   a , channels  22  between the components  6   a  and  6   b . When the shaft  6  is raised by means of flange  13 , air in the second chamber  10  is compressed and passes through apertures  24  and channels  22  in the lower component  6   b , in the direction of arrows  25 , to a mixing chamber  15 . 
     Referring again to  FIG. 2   a , the upper component  6   a  of the shaft  6  additionally comprises two disc like members  18   a  and  18   b . The upper disc like member  18   b  is a retainer and is shown in plan view in  FIG. 2   d , a section along the line A-A of  FIG. 2   a . The retainer  18   b , forming part of the upper component  6   a  of shaft  6 , has a narrow peripheral edge section which engages in a circumferential slot in the inner wall of the lower component  6   b  of the shaft  6 . This locks the two components  6   a  and  6   b  together. Apertures  18   d  in retainer  18   b  permit fluid to pass there through, as described below. 
     The lower disc like member  18   a , of  FIG. 2   a , is a diffuser and has an outer serrated edge  18   c . This edge together with the inner wall of the lower component  6   b  of shaft  6  defines a plurality of channels  18   e , each of a predetermined cross section, extending into a mixing chamber  15 , also defined by the upper component and the inner wall of the lower component  6   b  of the shaft  6 . 
     In the embodiment shown in  FIG. 2   a , the channels  18   e  are formed by the serrated edge  18   c  of the diffuser  18   a  engaging the inner wall of component  6   b . However in alternative arrangements, the channels could be formed as distributed apertures through the diffuser  18   a , or, as shown in  FIG. 2   e , the diffuser could have a smooth outer edge and the inner wall of component  6   b  could have vertical ridges  6   c  thereon, which would, in combination with the edge of the diffuser  18   a , define the channels. Each arrangement permits liquid soap to be injected into the mixing chamber  15  via a number of distributed channels, each of a predetermined cross section, which is not dependent on the pressure of the liquid soap passing there through, (represented by the arrows  3   b  of  FIG. 2   b  and  FIG. 3 ). 
     As seen from  FIG. 3 , when the shaft  6  is raised by the operation of the dispenser acting on flange  13  (relative to the position shown in  FIG. 2   a ), the upper component  6   a  of shaft  6  moves to a position where the piston  7  is no longer sealed by the O-ring  14 , permitting liquid soap  3 , displaced by the action of the piston  7  entering the first chamber  9 , to be forced down the side of the first piston  7  through apertures  18   d  of the retainer  18   b , and to enter into the channels  18   e  of the diffusers  18   a . The liquid  3  is sprayed under pressure as a plurality of jets from the channels into the mixing chamber  15 . Simultaneously, air is forced into the mixing chamber in the direction of arrows  25  causing the air and liquid to intermingle before exiting the mixing chamber  15  as a foam, via apertures  6   d  in the conical section  17  of the upper component  6   a  of shaft  6 , as shown in  FIG. 2   b.    
     As illustrated by  FIGS. 2   a  and  3 , the foam passes in the direction of arrows  27  down a central passage  19  formed by the lower component  6   b  of shaft  6  through a gauze  21 , which aggregates the foam bubble size, to outlet  20 . 
       FIG. 4  is a corresponding view to  FIG. 3  but shows the dispenser mechanism when the shaft  6  is fully depressed (raised) and reaches the limit of its travel. 
       FIG. 5  corresponds to  FIG. 4 , but shows the dispensing mechanism  1  midway through its return stroke, the dispensing mechanism being acted upon by the dispenser (not shown) drawing flange  13  in the direction of arrows  28  back to its rest position. During this part of the cycle, the expanding volume within the second chamber  10  draws air into the second chamber through the passage  19 , channels  22  and apertures  23 , as represented by arrows  29  and  30 . This draws any foam remaining in the passage  19  back into the bottom of the chamber  10 , from where it will be expelled back through the channels  22  to the mixing chamber  15  at the start of the next dispensing cycle. This ensures that at the end of the dispensing cycle passage  19  is free of foam and thus will not drip as the foam reverts back to liquid. With subsequent dispensing actions the volume of liquid soap  3  within the container  2  will be reduced and the container will collapse. 
       FIG. 6   a  is a side elevation of a wall mounted liquid soap dispenser  31  having an actuator handle  37  and  FIG. 6   b  is a front sectional view through the dispenser  31 . The dispenser  31  comprises a back plate  32  providing mounting for the dispenser mechanism  1  of  FIGS. 1 to 5 , shown here with an alternative type of collapsible container  2 . 
     The dispenser  31  has a main pillars  33  which are constrained and run in vertical bearing surfaces on the back plate  32 . The pillars  33 , located to either side of the dispenser, are attached to a main plate  34  as shown, with springs  35  acting between the main plate  33  and back plate  32  maintaining the main plate  34  in its lower position as shown. 
     Slots  36  in each of the main pillars  33  engage with pegs (not shown) of the actuator handle  37  of  FIG. 6   a , which handle provides a user interface by which a user may operate the dispenser. A user pressing the handle  37  causes the pegs of the handle to vertically raise the main pillars  33 . 
     A travelling plate  38  is attached by auxiliary pillars  39 , which auxiliary pillars  39  pass through holes in the main plate  33 , with springs  40  acting between a shoulder on the top of the auxiliary pillars  39  and the main plate  34  to retain the travelling plate in an upper position next to the main plate  34 , as shown. The travelling plate  38  is also attached to the flange  13  on the shaft  6  of the dispensing mechanism  1 , such that the shaft  6  moves with the travelling plate  38 . 
     Referring now to  FIGS. 7   a  and  7   b , these correspond to those of  FIGS. 6   a  and  6   b  but show the dispenser at full stroke, when the handle  37  has been fully depressed and is restrained by stops associated with the handle. The action of pressing the handle has raised the main pillars  33  to the position shown, whereby this in turn has raised the main plate  34 , travelling plate  38  and shaft  6  to its fully raised position, dispensing a predetermined quantity of foam. 
     Referring to  FIGS. 8   a  and  8   b , there is shown the same dispenser  31  fitted with an alternative dispensing mechanism  1   a  which has a reduced operating stroke. The dispensing mechanism  1   a  is fitted to the dispenser  31 , in the same manner as previously described with reference to  FIGS. 6   a  to  7   b . However, as shown in corresponding  FIGS. 9   a  to  9   b , partial depression of the handle  37  will complete a full stroke of the dispenser mechanism. If the handle  37  was directly linked to the dispenser mechanism  1   a , then further force depression of the handle  37 , which often occurs as a user will commonly “thump” the handle, would result in damage to the dispenser mechanism. However, as illustrated in  FIGS. 10   a  and  10   b , further depression of the handle  37 , to complete a full stroke of the handle, causes the travelling plate  38  to move away from the main plate  34  against the force exerted by springs  40 . Thus, the springs  40  act as a resilient means absorbing the extra displacement. This permits the dispenser  31  to be used with dispenser mechanisms having different full stroke lengths or may be arranged to permit the stroke length of the dispensing mechanism to be varied in order to control the quantity of foam, or other product to be dispensed. 
     The embodiment described above is given by way of example only and the scope of the invention is to be determined with reference to the appended claims.