WO2007125365A1

WO2007125365A1 - Dispenser mechanism for a foamed product

Info

Publication number: WO2007125365A1
Application number: PCT/GB2007/050214
Authority: WO
Inventors: Michael O'brien
Original assignee: Packaging Innovation Limited
Priority date: 2006-04-26
Filing date: 2007-04-25
Publication date: 2007-11-08

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 (6a, 6b), wherein the liquid and air are simultaneously forced into a foaming chamber (15, 22). The foaming chamber comprises at least one fin element (17) separating open portion (15) and closed portion (22) of the foaming chamber, with the liquid being forced from the closed portion (15) past the tip of the fin (17) into open portion (22) through which the air is flowing, where the liquid mixes with the air and forms a foam. 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

DISPENSER MECHANISM FOR A FOAMED PRODUCT

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.

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.

It is one object of a first aspect 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 arranged to simultaneously reduce the volume of both the liquid and air chambers; a foaming chamber; and at least one fin element separating an open portion of the foaming chamber from a closed portion of the foaming chamber, wherein the dispenser mechanism is arranged such that operation of the actuator mechanism causes the open portion to receive air from the air chamber and guide it to an outlet of the dispenser mechanism and the closed portion to simultaneously receive liquid from the liquid chamber, the at least one fin element being dimensioned such that liquid in the closed portion is forced past the tip of the fin element to the open portion where it is mixed with air flowing in the open portion to form a foamed product.

The invention permits efficient mixing of the liquid and air in a very compact arrangement/ space.

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 piston, as this can provide a very compact arrangement.

Preferably, the first piston has an inward facing surface of an outer wall and an outward facing surface of an inner wall or shaft, wherein the at least one fin element extends in a radial direction from the surface of one wall or shaft to separate the open and closed portions of the foaming chamber.

Preferably, said open portion is connected to an internal passage within the piston, through which foam products can be dispensed to the outlet of the dispenser mechanism. This is particularly advantageous where the shaft of the piston is arranged vertically with the first piston on the top of the shaft extending into the first chamber, the liquid chamber, with the shaft having a second piston arranged coaxially with the shaft below the first piston with the second piston acting on the air chamber located below the liquid chamber, wherein apertures located at the bottom of the first piston towards the second piston connect the air chamber to the open portion, which in turn is connected to the internal passage towards the top of the first piston and wherein a closed portion is connected to the liquid chamber via an aperture located towards the top of the first piston. - A -

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 then be arranged to 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, for 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.

Advantageously, the at least one fin element comprises a resilient material and distorts due to pressure differences between adjacent closed and open portions of the foaming chamber.

A dispenser mechanism in accordance with the invention is particularly advantageous in manually operated applications, such as soap dispensers.

The foaming chamber may comprise a plurality of fins extending from one surface towards another surface of the foaming chamber, each fin separating an open portion from a closed portion of the foaming chamber to define a plurality of open and closed channels, with liquid being forced in operation past the tip of each fin. This arrangement provides a plurality of open and closed channels extending in the axial direction of the actuator.

In an alternative arrangement, the at least one fin element is substantially planar and extends across the foaming chamber in a plane perpendicular to an axis of the actuator mechanism, with the tip of the fin element extending around the periphery of the fin. With this arrangement, the fin element can be in the form of a single, preferably circular, disc sealing at its tip around a peripheral edge with the inner surface of a cylinder defined by an inner facing wall of the foaming chamber.

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. T wo embodiments of the present invention will now be described, by way of example only, with reference to Figures 1 to 20, in which like numerals are used throughout to indicate like parts, and in which:

Figure 1 is a cross-section through a dispensing mechanism in accordance with a first embodiment of the present invention, with a transport cap in place;

Figure 2a is a corresponding cross-section to that of Figure 1 but with the transport cap removed;

Figure 2b is a section along the line II-II of Figure 2a, shown to an enlarged scale;

Figures 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a and 7b are sectional views respectively corresponding to those of Figures 2a and 2b, but depicting the various stages of operation of the dispensing mechanism;

Figure 8 depicts how the liquid container collapses as liquid is dispensed;

Figure 9a is a side elevation of the dispenser mechanism additionally illustrating a user interface for the dispenser mechanism described with reference to Figures 1 to 8;

Figure 9b is a front sectional view of the dispenser of Figure 9a;

Figures 10a, 10b, 11a, l ib, 12a, 12b, 13a and 13b corresponding to those of Figures 9a and 9b but depict the dispenser in various stages of operation;

Figure 14 is a cross-section through a dispensing mechanism in accordance with a second embodiment of the invention which has a modified foaming chamber to that of the embodiment illustrated in Figures 1 to 13. However, in all other respects the dispenser mechanism is identical and like numerals are used to indicate corresponding parts to those in Figures 1 to 13. Figures 15 to 20 are cross-sections and respective selectively enlarged cross- sections of the dispenser of Figure 14, illustrating different stages of operation of the dispenser mechanism.

Referring to Figure 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 are disposable, that is to say they are provided as a refill pack for a wall mounted soap dispenser.

In the embodiment illustrated in Figure 1 , because the dispenser mechanism is disposable and is transported attached to the filled container 2, the dispenser mechanism comprises a transport cap 4, secured to the housing 5 of the dispenser mechanism to prevent accidental actuation of the dispenser mechanism.

The dispenser mechanism comprises an inner shaft 6a and an outer shaft 6b (together hereinafter referred to as shaft 6), an upper portion of inner shaft 6a defines a first piston 7 and a lower portion of outer shaft 6b supporting a second piston 8, mounted coaxially on the outer shaft 6b.

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. This 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 Figure 1, the shaft 6 and associated piston 7 and 8 are retained in a fully depressed, 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 Figure 2a, a corresponding view to that of Figure 1 is shown but with the transport cap 4 removed. When the transport cap has been removed and the dispenser mechanism installed in a dispenser (as described below with reference to Figures 9a to 13b) the mechanism of the dispenser, not shown in Figure 2a, biases flange 13 located towards the bottom of outer shaft 6b to the position shown in Figure 2a. Here a rubber O- ring seal 14 seals with the first piston 7. The O-ring 14 is retained in place by end cap 14a. Drawing the shaft 6 downwards causes liquid soap 3 to flow into the first chamber 9.

As most clearly seen in Figure 2a, the inner shaft 6a and outer shaft 6b define channels which are sealed at the bottom portion, where the inner shaft 6a is joined to the outer shaft 6b and thus only have apertures 16 at the top thereof. These are hereinafter referred to as closed channels 15. As can be more clearly seen from Figure 2b, a cross-section through the plane II-II of Figure 2a, closed channels 15 are defined by the inner surface of outer shaft 6b and the outer surface of inner shaft 6a, with fins 17 extending from the outer surface of the inner shaft 6a towards the inner surface of the outer shaft 6b.

Figure 3a corresponds to Figure 2a and Figure 3b is a sectional view in the plane HI-III of Figure 3 a. In Figure 3 a the shaft 6 has been raised by the operation of the dispenser acting on flange 13, relative to the position shown in Figure 2a. In Figure 3a, the dispensing mechanism is partway through its dispensing cycle. The shaft 6 has moved to a position where the apertures 16 at the top of the closed channels 15 are 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 and to enter into the channels 15 via the apertures 16.

Because the closed channels 15 are sealed at the bottom, the now pressurised liquid soap 3 is forced past the tips of the radially extending fins 17, potentially distorting the fins if the dispenser is vigorously actuated causing liquid to be forced into adjacent channels (hereinafter referred to as open channels 22) as represented by arrows 18.

From Figures 3a and 3b, a central passage 19 is seen formed by the inner shaft 6a and outer shaft 6b. The lower end of passage 19 terminating at outlet 20. Located in the passage is a gauze 21. Referring now to Figure 4a and 4b, these are corresponding views to Figure 3a and 3b at the same stage of operation, but with the dispenser mechanism rotated through 90°.

In Figures 4a and 4b, the open channels 22 are seen to be connected by apertures 23 to the second chamber 10 and by apertures 24 to the inner passage 19, such that as the second piston 8 displaces air from the chamber 10, the air is forced through the open channels 22 in the direction of arrows 25 and 26. The air then passes up the open channels 22 (out of the paper as shown in Figure 4b) at the same time as the liquid soap 3 is forced past the tips of fins 17, as represented by the arrows 18 in Figure 4b, to form a foam which travels down passage 19 via the gauze 21, which aggregates the foam bubble size, in the direction of arrow 27 and out through the outlet 20.

Figure 5a and 5b are corresponding views to those of Figures 3a and 3b but show the dispenser mechanism when the shaft 6 is fully depressed and reaches the limit of its travel. Figures 6a and 6b are corresponding views to Figures 5a and 5b but show the dispenser mechanism rotated through 90°.

Figures 7a and 7b correspond to the set of Figures 4a and 4b, but show 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 and open channels 22, 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 open channels 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.

As shown in Figure 8, with subsequent dispensing actions the volume of liquid soap 3 within the container 2 will be reduced and the container will contract as shown.

Figure 9a is a side elevation of a wall mounted liquid soap dispenser 31 having an actuator handle 37 and Figure 9b is a front sectional view through the dispenser 31. The dispenser 31 comprises a back plate 32 providing mounting for the dispenser mechanism 1 and container 2 of Figures 1 to 8.

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 back 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 Figure 9a, 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 Figures 10a and 10b, these correspond to those of Figures 9a and 9b 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 Figures 11a and 1 Ib, there is shown the same dispenser 31 fitted with an alternative dispensing mechanism 1 a which has a reduced operating stroke. The dispensing mechanism Ia is fitted to the dispenser 31, in the same manner as previously described with reference to Figures 9a to 10b. However, as shown in corresponding Figures 12a to 12b, 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 Ia, 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 Figures 13a and 13b, 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.

Referring now to Figures 14 to 20, there is illustrated a second embodiment of the present invention shown in its different stages of operation. This embodiment differs only from that illustrated and described with reference to Figures 1 to 8 in that the inner shaft 6a has a different configuration. The dispenser mechanism of Figures 14 to 20 may be substituted for the corresponding section of the mechanism illustrated in Figures 9 to 13.

With the exception of the inner shaft 6a and the associated foaming chamber, the mechanism of Figures 14 to 20 functions in exactly the same manner as previously described with reference to Figures 1 to 13. For this reason, the following description of Figures 14 to 20, essentially describes only those aspects which differ from the embodiment previously described.

Referring to Figure 14, the dispenser mechanism of the second embodiment is shown with the transport cap 4 in place. At the commencement of operation, the transport cap is removed and downward action on the flange 13 causes it to adopt the position shown in Figure 15a and Figure 15b, Figure 15b being enlarged section showing the inner shaft 6a of Figure 16a.

The inner shaft 6a has a central wasted section which defines a foaming chamber having a closed portion 41 and an open portion 42. These sections are separated by a disc shaped fin element 47, integrally formed with the inner shaft 6a. The outer dimension of the fin element 47 corresponds to the inner diameter of the upper portion of the outer shaft 6b.

Below the waisted region 41, 42 the inner shaft has a plurality of axially extending grooves (not shown) in its outer surface defining channels 44 connecting the open portion 42 of the foaming chamber to the second chamber 10 via apertures 23.

In the conical section 48 of the inner shaft 6a, a plurality of apertures 45 are formed connecting the open portion 42 of the foaming chamber to the open outlet 19 of the dispenser mechanism.

Above the closed portion 41 of the foaming chamber, a plurality of grooves 46 are formed in the external surface of the inner shaft 6a forming apertures extending between the closed portion 41 and the based of piston 7.

The action of moving the shaft 6a, 6b down fills the first chamber 9 with fluid drawn into the chamber 9 via non-return valve 11 , as described with reference to the first embodiment. When in a "fully primed" state, as illustrated in Figure 15 a, the chamber 9 is sealed by piston 7 engaging with O-ring 14.

At commencement of the dispensing operation, the flange 13 is moved upwards to the position shown in Figure 16, where the outer shaft 6b seals with O-ring 14. Continued raising of the shaft 6a, 6b causes the non-return valve 11 to seal the first chamber 9, as illustrated in Figures 17a and 17b. Now the closed portion 41 of the foaming chamber, together with grooves 46, the gap around the piston 7 and first chamber 9, define a closed volume filled with a substantially incompressible liquid. This same movement of the shaft 6a, 6b causes second piston 8 to displace air from the second chamber 10 forcing air in the direction of broken arrows 48 of Figure 17b, into the open portion 42 of the foaming chamber. The air swirls about the open portion 42 of the chamber and exists via apertures 45 to the outlet passage 19. During this process, the liquid in the closed portion 41 of the foaming chamber is forced past the tip of the fin element 9, in the direction of arrows 49, mixing with the air, as indicated by arrows 50. This forms a foam which passes through the outlet passage in the direction of arrow 51.

The action described with reference to Figures 17a and 17b continues until the dispenser reaches the end of its stroke as illustrated in Figures 18a and 18b. At this point, the flange 13 is drawn downwards, increasing the volume of the second chamber 10 drawing foam in the outlet passage 19 back into the bottom of the second chamber 10, as represented by the arrows 52 of Figures 19a and 19b. At the same time, liquid is drawn into the first chamber 9 via non-return valve 11. This continues until piston 6 reaches the bottom of its stroke as illustrated in Figure 20 with the container 2 collapsing as liquid 3 is removed from the container 2. The mechanism is this returned to it's "primed state" awaiting the next dispensing cycle.

The two embodiments described above are given by way of example only and the scope of the invention is to be determined with reference to the appended claims.

Claims

1. 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 arranged to simultaneously reduce the volume of both the liquid and air chambers; a foaming chamber; and at least one fin element separating an open portion of the foaming chamber from a closed portion of the foaming chamber, wherein the dispenser mechanism is arranged such that operation of the actuator mechanism causes the open portion to receive air from the air chamber and guide it to an outlet of the dispenser mechanism and the closed portion to simultaneously receive liquid from the liquid chamber, the at least one fin element being dimensioned such that liquid in the closed portion is forced, past the tip of the fin element, to the open portion where it is mixed with air flowing in the open portion to form a foamed product.

2. A dispenser mechanism as claimed in Claim 1, wherein the actuator mechanism comprises a first and a second piston on a common shaft, each piston acting on a respective one of the liquid and air chambers.

3. A dispenser mechanism as claimed in Claim 2, wherein a first chamber is in the form of a cylinder into which the first piston extends to pressurise the contents of the chamber and wherein the foaming chamber is formed in the piston.

4. A dispenser mechanism as claimed in Claim 3, wherein the first piston has an inward facing surface of an outer wall and an outward facing surface of an inner wall or shaft, wherein the at least one fin extends in a radial direction from the surface of one wall or shaft to separate the open and closed portions.

5. A dispenser mechanism as claimed in Claim 4, wherein the open portion is connected to an internal passage within the piston through which the foamed product can pass to the outlet of the dispenser mechanism.

6. A dispenser mechanism as claimed in Claim 5, wherein the shaft is arranged vertically with the first piston on the top of shaft extending into the first, liquid, chamber, the shaft having a second piston arranged coaxially with the shaft below the first piston, with the second piston acting on the air chamber located below the liquid chamber, wherein apertures are located at the bottom of the first piston towards the second piston, which apertures connect the air chamber to the open portion which open portion is connected to the internal passage and wherein the closed portion is connected to the liquid chamber by at least one aperture located towards the top of the first piston.

7. A dispenser mechanism as claimed in any preceding claim, wherein the actuator mechanism is biased to a rest position where the pistons associated with each respective chamber are withdrawn to their maximum extent from their respective chambers.

8. A dispenser mechanism as claimed in Claim 7, wherein in the rest position the liquid chamber is sealed by its associated piston.

9. A dispenser mechanism as claimed in Claim 7 or 8, wherein 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.

10. A dispenser mechanism as claimed in any preceding claim, wherein the liquid chamber has a piston and 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 and 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 the valve in a closed position.

11. A dispenser mechanism as claimed in any preceding claim, wherein the at least one fin element is resilient and distorts due to pressure differences between adjacent closed and open portions of the foaming chamber.

12. A dispenser mechanism as claimed in any preceding claim, wherein the foaming chamber comprises two surfaces and a plurality of fins extend from one surface towards said other surface of the foaming chamber, each fin separating an open portion from a closed portion of the foaming chamber to define a plurality of open and closed channels with liquid being forced in operation past the tip of each fin from a closed channel to an open channel.

13. A dispenser mechanism as claimed in Claim 12, wherein the open and closed channels extend in an axial direction of the actuator mechanism.

14. A dispenser mechanism as claimed in any one of Claims 1 to 11, wherein the at least one fin element is substantially planar and extends across the foaming chamber in a plane perpendicular to an axis of the actuator mechanism with the tip of the fin element extending around a periphery of the fin.

15. A dispenser mechanism as claimed in any preceding claim, arranged to be manually operated.

16. A dispenser mechanism as claimed in any preceding claim, further comprising a user interface for receiving a single stroke actuation by a user, for dispensing a predetermined quantity of product to the user on a full stroke of the dispenser mechanism and a linkage mechanism for transferring 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 to the dispenser mechanism only as much of the operation of the interface as is required to permit the dispenser mechanism to dispense the predetermined amount of product.

17. A dispenser mechanism as claimed in Claim 16, wherein the linkage mechanism comprises a resilient device arranged between the interface and the dispenser mechanism, the properties of the resilient device being such as to fully actuate the dispenser mechanism on operation of the interface but which resilient device absorbs any excess movement of the interface to prevent damage to the dispenser mechanism.

18. A dispenser mechanism as claimed in Claim 17, wherein the linkage mechanism comprises a first plate connected to the user interface and arranged to move with the user interface, a second plate connected to the dispenser mechanism, and at least one resilient member arranged to act between the first plate and the second plate, the resilient member being selected such that it will cause the two plates to be displaced together in response to any movement of the user interface to cause the dispenser mechanism to be operated but which, when the dispenser mechanism reaches the end of its travel, permits the first plate to continue to be displaced whilst the second plate remains substantially stationary.

19. A dispenser mechanism as claimed in any one of Claims 16 to 18 for dispensing soap and arranged to be wall mounted and permit single handed one stroke operation.

20. A dispenser mechanism as claimed in any preceding claim, wherein reducing the volume of both the liquid and air chambers pressurises the contents of the chambers and the closed portion receives pressurised liquid from the liquid chamber and wherein the liquid is forced under pressure past the tip of the fin element.