The present invention relates to liquid dispensers. In particular the present invention relates to liquid {especially soap) dispensers thai may dispense either foamed or unfoamed liquid.

Liquid dispensers may be used to dispense various liquids including soap, Liquid dispensers (especially soap dispensers) are known in which the liquid is mixed with air (or other gas) prior to being dispensed in order to form a foam. Advantages of foam soap dispensers are that relatively less soap is used and also the look and feel of the foam soap are considered, by users, to be better. Additionally, foam soap is considered to lather and mix better with water leading to a perception of improved cleaning.

EP-A-1 974 840 relates to a foam soap dispenser for producing foamed soap using a stationary dispensing tube.

There is however, a need for, in some circumstances, unfoamed (i.e. more concentrated) soap and other liquids.

It is an aim of the present invention to address this problem and to provide dispensers which may dispense either foamed or unfoamed liquids.

The present invention accordingly provides a liquid dispenser comprising, an outlet for dispensing liquid, mixing means for mixing liquid and gas, liquid supply means, and gas supply means, wherein the outlet, mixing means, liquid supply means and/or gas supply means are so arranged that in a first condition liquid and gas may be supplied by the liquid supply means and gas supply means respectively through the mixing means to the outlet thereby dispensing foamed liquid from the outlet, or in a second condition liquid may be supplied to the outlet, thereby dispensing unfoamed liquid from the outlet.

This is beneficial because the dispenser may be used to dispense either foamed or unfoamed liquid at the choice of the user and/or installer of the liquid dispenser. Preferably, in the second condition, liquid is supplied through the mixing means to the outlet This is advantageous because the same genera! path may be used for the liquid in both foam and non-foam conditions, simplifying construction. Usually, the liquid will be soap. Alternatively, the liquid may be lotion, cream or another cleaning or personal care liquid.

Usually the gas will be air.

in a preferred embodiment, the gas supply means is so arranged that it may be put in a first condition for supplying gas to the mixing means thereby providing foamed liquid, or in a second condition where gas is not supplied to the mixing means thereby providing unfoamed liquid.

Thus preferably, in a second embodiment of the present invention, there is provided a liquid dispenser, comprising an outlet for dispensing liquid, mixing means for mixing liquid and gas, liquid supply means for supplying liquid to the mixing means, and gas supply means which may be put in a first condition for supplying gas to the mixing means to form a foam liquid and in a second condition where gas is not supplied to the mixing means thereby providing unfoamed liquid.

Generally, the way in which the gas/air supply is changed from supply to not being supplied to the mixing means may be achieved in various ways, for example, by disconnecting the air supply either at the nozzle or at the pump which supplies the air and liquid or, alternatively, by diverting (via for example, a dsverter valve) the air supply to atmosphere. In a preferred embodiment of the present invention, however, the liquid continues to pass through the mixing means whether or not air/gas is supplied to the mixing means and whether or not the device dispenses foamed or unfoamed liquid,

In an alternative embodiment, the liquid may be diverted around the mixing means to a secondary outlet of the nozzle in order to provide unfoamed soap, passing through the mixing means together with the gas supply in order to produce foamed soap.

Preferably the mixing means is a passive {i.e. with no moving parts) mixing means. Generally the mixing means will comprise one or more shear regions. The nature of the shear regions will depend upon other aspects of the design of the nozzle (and the rest of the dispenser). Examples of suitable shear regions include passageways (preferably with relatively sharp changes of direction) other types of mixing manifold, baffles, gauzes and/or meshes. Orifices providing relatively high shear at the edges may be used.

Preferabiy, the dispenser further comprises a check valve to prevent liquid being pumped info the gas supply means.

Preferably the dispenser further comprises a return valve so arranged as to reduce drips after liquid is dispensed from the outlet.

Thus, in a third embodiment the present invention provides a liquid dispenser comprising an outlet for dispensing liquid, liquid supply means and a return valve for reducing liquid drips after liquid is dispensed from the outlet, Preferabiy, the return valve comprises a poppet valve, more preferably a sprung poppet value which is assisted to return by a spring (preferabiy a relatively low rate spring). Preferably, when the poppet valve closes (after the liquid has been dispended) the volume displaced by this action will tend to draw excess liquid into the nozzle, thereby preventing or reducing liquid drips.

Supply of soap and/or gas in the dispenser may be achieved in various ways, in particular, a liquid/gas pump may be used, preferabiy a pump which provides both liquid and gas at the same time. The liquid/gas pump may be either mechanically driven (e.g. eiectromechamcal!y driven) or manually driven depending on the use to which the dispenser is to be put.

An embodiment of the invention will now be described, by way of example, with reference to the attached drawings in which

Figure 1 is an exploded view of a nozzle/liquid dispenser according to the present invention and

Figure 2 is a vertical .section through the liquid dispenser.

Figures 1 and 2 illustrate a liquid dispenser 14 consisting of a nozzle. Nozzle 14 comprises an inlet 10 for a liquid (preferabiy a soap) from a soap pump and an inlet 12 for air from an air pump. The soap and/or air pump can be of various sorts including (and preferabiy) a combined soap and air pump (not shown). When soap is to be dispensed from the liquid dispenser, soap is pumped from the soap pump and enters the soap inlet 10 and passes through a passageway in the soap inlet cap 2 to poppet valve 6. The poppet valve 6 opens within the nozzle body 3 allowing passage of the soap through a narrow soap entry passageway 22 (shown in Fig 2). At the same time air passes from the air pump into air inlet 12 and through a convoluted passageway within nozzle body 3 (where it undergoes mixing under shear with the soap). If it is intended not to dispense foam soap then the air inlet is disconnected (or diverted) away from the passageway by a diverter vaive (not shown) or a gas disconnector (not shown) which results in soap not mixing with air and thereby not forming a foam.

The foam soap passes through mesh member 1 where there is further mixing between air (if pumped in) and soap and the foam soap is dispersed from the outlet 16 in outlet member 7. Once the soap has been dispensed the poppet valve 6 closes by action of low rate return spring 8. The volume displaced by this return of the poppet valve 6 within the body of the nozzle 14 draws any excess soap back into the nozzle body 3 or outlet member 7 thereby preventing soap drips. A check valve (not shown) is situated in the air supply line leading to the air iniet 12 so arranged that if the air supply is removed (for example when unfoamed soap is to be dispensed or otherwise) no soap can be pumped up the air hose.

Figure 2 illustrates a section through the assembled nozzle 14. Figure 2 shows that soap inlet 10 is connected to soap entry passageway 22 sealed by the poppet valve 6 after and before soap is dispensed. When soap is pumped through the soap inlet 10 into the soap entry passageway 22 the poppet valve 6 opens (compressing low rate return spring 8) and soap passes through first part 18 of the mixing passageway through the second part 20 of mixing passageway. At the same time (when foam soap is to be dispensed) air is pumped info air iniet 12 and mixes at least at second part 20 of mixing passageway with the soap under shear thereby forming a foam soap. The foam soap passes through orifice 24 (ensuring further mixing) and into mesh tube 1 where still further mixing takes place. Foam soap is dispensed through dispensing outlet 16,

If it is not desired to produce foam soap then the air supply is disconnected so no air enters the air inlet 12 or, alternatively^ diverted away to atmosphere,