Liquid dispensing apparatus

1. A discharge assembly for discharging a metered volume of a liquid held in a pressurised or pressurisable container, said assembly comprising:

(i) an elongate tubular housing having a liquid inlet at a first end thereof,

(ii) a valve stem having a body locating within said housing and having a portion projecting from the second end of said housing, said valve stem being axially moveable relative to the housing between a first limit portion at which the assembly is closed to liquid discharge and a second limit position for discharge of the metered volume,

(iii) a chamber provided within the body of the valve stem and having a liquid inlet at a first end of the chamber adjacent said first end of the housing and a first fluid transfer passageway towards the opposite, second end of the chamber, said first fluid transfer passageway providing communication between the chamber and the exterior of the valve stem, and

(iv) a liquid discharge element moveable along said chamber from a liquid primed position to a liquid discharged position to effect discharge of the metered volume of liquid,

wherein

(a) the exterior of the body of the valve stem and the interior of the housing are configured such that in the first position of the valve stem there is second fluid transfer passageway along the outside of the valve stem between the inlet of the housing and a head portion of said valve stem, and

(b) a seal is provided for relative sliding movement onto an annular step as the valve stem moves from its first to second position to close said second fluid transfer passageway to fluid flow,

wherein the liquid discharge element is spherical;

wherein the liquid discharge element is free from physical contact with a return spring.

2. A discharge assembly as claimed in claim 1 wherein the seal is provided on the exterior of the body of the valve stem and the annular step is provided on the interior surface of the housing.

3. A discharge assembly as claimed in claim 2 wherein the seal is an O-ring.

4. A discharge assembly as claimed in claim 2 wherein the seat is downwardly inclined away from the second end of the housing.

5. A discharge assembly as claimed in claim 1 wherein the liquid discharge element is moveable by a returning force from its liquid discharged position to its liquid primed position.

6. A discharge assembly as claimed in claim 5 wherein the liquid discharge element is negatively buoyant in the liquid to be dispensed so as to provide at least a part of said returning force.

7. A discharge assembly as claimed in claim 1 wherein the head portion is moveable within an annular seal provided at the second end of the housing and said head portion has an open-topped conduit communicating with an outlet of the head portion, said open-topped conduit being external of the housing in the first position of the valve stem and within the housing in the second position thereof.

8. A discharge assembly as claimed in claim 1 wherein the inlet to the housing is coaxial with said chamber.

9. A discharge assembly as claimed in claim 8 which is such that with the valve stem in its second limit position and the discharge element at its liquid primed position there is a refill flow passageway arrangement between the liquid inlet of the housing and the chamber provided within the body of the valve stem to permit re-filling of a container on which the discharge assembly is mounted in use, and wherein

(a) a tubular spigot is provided within the elongate tubular housing around the liquid inlet thereof, and

(b) said refill passageway arrangement is provided by at least one cut away portion of said tubular spigot and at least one slot of the chamber accessible to fluid when the discharge element is at its liquid primed position.

10. A discharge assembly as claimed in claim 1 which is such that with the valve stem in its second limit position and the discharge element at its liquid primed position there is a refill flow passageway arrangement between the liquid inlet of the housing and the chamber provided within the body of the valve stem to permit re-filling of a container on which the discharge assembly is mounted in use.

11. A liquid dispensing apparatus provided with a discharge assembly as claimed in claim 1 for discharging the metered volume of a liquid held in a pressurised or pressurisable container of the apparatus.

12. A liquid dispensing apparatus as claimed in claim 11 wherein the container is pressurised with nitrogen, air, liquefied natural gas, liquefied hydrocarbon gas or carbon dioxide.

13. A liquid dispensing apparatus as claimed in claim 11 which is an aerosol spraying device.

14. A liquid dispensing apparatus as claimed in claim 11 which contains a material selected from the group consisting of pharmaceutical, agrochemical, fragrance, air freshener, odour neutraliser, sanitizing agent, polish, insecticide, depilatory chemical (such as calcium thioglycolate), epilatory chemical, cosmetic agent, deodorant, anti-perspirant, anti-bacterial agents, anti-allergenic compounds, and mixtures of two or more thereof.

15. A liquid dispensing apparatus as claimed in claim 11 which contains a foamable composition.

16. A liquid dispensing apparatus with a discharge assembly for discharging a metered volume of a liquid held in a pressurised container of the apparatus wherein the apparatus has a metering chamber incorporating a liquid discharge element which is moveable by fluid pressure from the container from a liquid primed position to a liquid discharged position to effect discharge of said metered volume of liquid and is moveable by a returning force from its liquid discharged position to its liquid primed position wherein the discharge assembly is as claimed in claim 1 .

17. A liquid dispensing apparatus with a discharge assembly for discharging a metered volume of a liquid held in a pressurised container of the apparatus wherein the apparatus has a metering chamber incorporating a liquid discharge element which is moveable by fluid pressure from the container from a liquid primed position to a liquid discharged position to effect discharge of said metered volume of liquid and is moveable by a returning force from its liquid discharged position to its liquid primed position,

wherein the liquid discharge element is spherical;

wherein the liquid discharge element is free from physical contact with a return spring.

18. Apparatus as claimed in claim 17 which comprises:

(i) an actuator assembly incorporating a valve stem adapted for movement from a first limit position to a second limit position, said valve stem having a discharge conduit arrangement with an inlet through which liquid is introduced into the discharge conduit arrangement and an outlet from which liquid is discharged from the apparatus, and

(ii) a valving arrangement such that when the valve stem is in its first limit position liquid may not flow out of the metering chamber through the inlet/outlet arrangement into the discharge conduit and when the valve stem is in its second limit position liquid may flow out of the metering chamber through the inlet/outlet arrangement into the discharge conduit.

19. Apparatus as claimed in claim 18 wherein the discharge assembly comprises a housing and wherein

(i) an annular space is provided between the inner surface of the housing and the outer surface of the valve stem,

(ii) the metering chamber comprising the liquid discharge element is provided internally to the valve stem.

20. A liquid dispensing apparatus as claimed in claim 19 wherein

(i) the housing is an elongate tubular housing having a liquid inlet at a first end thereof,

(ii) the valve stem has a body located within said housing and having a portion projecting from the second end of said housing,

(iii) the metering chamber has a liquid inlet at a first end of the chamber adjacent said first end of the housing and a first fluid transfer passageway towards the opposite, second end of the chamber, said first fluid transfer passageway providing communication between the chamber and the exterior of the valve stem,

(iv) the exterior of the body of the valve stem and the interior of the housing are configured such that in the first position of the valve stem there is second fluid transfer passageway along the outside of the valve stem between the inlet of the housing and a head portion of said valve stem, and

(v) the valving arrangement comprises a seal provided for relative sliding movement onto a seat as the valve stem moves from its first to second position to close said second fluid transfer passageway to fluid flow.