WO2018210434A1

WO2018210434A1 - A dispensing system for a pressurized fluid medium, a valve cup assembly and a method of assembling such a system

Info

Publication number: WO2018210434A1
Application number: PCT/EP2017/062144
Authority: WO
Inventors: Adalberto Geier; Valentino STENGHEL
Original assignee: Coster Tecnologie Speciali S.P.A.
Priority date: 2017-05-19
Filing date: 2017-05-19
Publication date: 2018-11-22

Abstract

The present invention provides a fluid medium dispensing system (1) for dispensing a fluid medium stored under pressure. The system comprises a container (5) for storing the fluid medium under pressure, the container having a neck (10) that defines an opening (11). A valve cup (2) closes the opening (11) of the container (1) and supports a valve (6) for dispensing its contents. The valve cup (2) comprises a first part (14) that is located in the opening (11) and a second part (15) that covers a rim (12) of the neck (10). A locking ring (4) is secured to the valve cup (2) to retain it in position in the neck (10) of the container (5). During assembly of the system (1) the locking ring (4) is initially secured to the valve cup (3) in a first position wherein it surrounds the second part (15) of the valve cup (3). Thereafter, the locking ring (4) is movable from the first position into a second position wherein it is made fast to the valve cup (2) to retain the valve cup (2) in position during use of the system (1). Advantageously, the locking ring (4) is secured to the valve cup (2) in both its first and its second positions. Preferably also, the second part (15) of the valve cup (3) snap-fits around the rim (12) of the neck (10) of the container (5). Also provided do a valve cup assembly (2) comprise the valve cup (3) and the locking ring (4) and a method of assembling the fluid dispensing system (1).

Description

A Dispensing System for a Pressurized Fluid Medium,

a Valve Cup Assembly and a Method of Assembling such a System

Description

The present invention relates to a system for dispensing a pressurized fluid medium that incorporates a valve cup assembly and to a method of assembling such a system. Specifically the invention relates to the valve cup assembly and the manner in which it is attached to the body of a container to form a pressurized fluid dispending system.

Background

Systems for dispensing a fluid medium stored under pressure are well-known and typically include a container, a valve and a valve cup, wherein the valve cup supports the valve, usually centrally, and also closes off an opening of the container. The inner volume of the container is pressurized and maintained in such a state by the valve and seals between the valve cup and valve, and the valve cup and the container opening. When the valve is actuated, the pressure difference between the inner volume of the container and the outside environment causes the fluid medium to be expelled from the container. Some systems employ a two-stage container having an inner and outer container, one of which contains the propellant gas, whereas others may employ a single container with the fluid medium also acting as the propellant.

Traditionally, the containers are made from metal, usually thin aluminium and the valve cup and valve are primarily made of plastics materials. It will be appreciated that it is important that the dispensing system is stable with the seals between the various components of the system being able to withstand the internal pressures of the container. European safety standards require appropriate sealing performance at temperatures in excess of 50°C.

However, because of the ubiquitous nature of systems for dispensing pressurized fluid media, it is important that the cost of the components making up the system and of the assembly process itself are kept low so that the cost of the finished product is commensurate with the cost of the fluid media. Hence it is important that the components of a dispensing system can be manufactured economically and the system easily assembled, particularly as it is often the case that the components are manufactured by one company and the dispensing system itself is assembled and filled by another company.

The object of the present invention is to provide a fluid medium dispensing system, a valve cup assembly and a method of assembling such a system that address these issues and enable the components of the valve cup assembly manufactured economically and efficiently and in a manner that simplifies the method of assembling the system.

Summary

According to a first aspect of the present invention there is provided a fluid medium dispensing system comprising:

a container for storing a fluid medium under pressure, the container comprising a neck defining an opening;

a valve;

a valve cup adapted to support the valve and to close the opening of the container, a first part of the valve cup locating in the opening and a second part of the valve cup covering a rim of the neck defining the opening; and

a locking ring that is secured to the valve cup to retain the valve cup in position in the neck of the container;

characterized in that during assembly of the system the locking ring is initially secured to the valve cup in a first position wherein it surrounds the second part of the valve cup and in that the locking ring is movable from the first position into a second position wherein it is made fast to the valve cup to retain the valve cup in position during use of the system.

According to a second aspect of the present invention there is provided a valve cup assembly comprising a valve cup and a locking ring for a fluid medium dispensing system, the valve cup comprising a first part adapted to support a valve and to locate in an opening defined by a neck of a container and a second part adapted to cover a rim of the neck defining the opening; and

the locking ring adapted to be secured to the valve cup;

characterized in that the locking ring is secured to the valve cup in a first position surrounding the second part of the valve cup and is movable from the first position into a second position wherein it is made fast to the valve cup.

According to a third aspect of the present invention, there is provided a method of assembling a fluid dispensing system for dispensing a fluid medium stored under pressure, the method including:

providing a container, the container being suitable for storing a fluid medium under pressure and comprising a neck that defines an opening; providing a valve cup comprising a first part adapted to support a valve and to locate in the opening of the container and a second part adapted to cover a rim of the neck; providing a locking ring adapted to be secured to the valve cup in a first position surrounding the second part of the valve cup and that is capable of movement relative to the valve cup from the first position into a second position wherein it is made fast to the valve cup;

securing the locking ring to the valve cup such that it is in its first position; providing a valve with a valve housing and securing the valve housing to the first part of the valve cup;

positioning the valve cup at the opening of the container and push-fitting it in the opening so that the first part is located in the opening and the second part covers the rim;

moving the locking ring from its first position into its second position wherein it is made fast with the valve cup; and

charging the internal volume of the container.

Preferably, wherein the locking ring moves axially in a direction parallel to its longitudinal axis when moving from its first position into its second position. Advantageously, the locking ring is secured to the valve cup in its first position by snap-fitment; the locking ring is made fast to the valve cup in its second position by snap-fitment; and the second part of the valve cup snap-fits around the rim of the neck of the container.

Other preferred additional features of the various aspects of the present invention are described in the dependent claims appended hereto.

Description of the Drawings

Fig. 1 is a plan view of a valve cup assembly in accordance with the second aspect of the present invention with a locking ring thereof is in its second position;

Fig. 2 is a sectional view along the line II-II in Fig. 1 showing the valve cup assembly inserted into a neck of a container to provide a fluid medium dispensing system in accordance with the first aspect of the present invention;

Fig. 3 is a scrap view from above of a valve cup of the valve cup

assembly;

Figs. 4 and 5 are respectively sectional views along the lines IV-IV and V-V of

Fig. 3;

Figs. 6 and 7 are respectively isometric views from above and from below of the valve cup shown in Figs. 4 and 5;

Fig. 8 is a scrap view from above of a locking ring of the valve cup assembly;

Figs. 9 and 10 are respectively sectional views along the lines IX-IX and X-X of

Fig. 8; Figs. 11 and 12 are respectively isometric views from above and from below of the locking ring shown in Figs. 9 and 10;

Fig. 13 is a plan view of the valve cup assembly when the locking ring is in its first position;

Fig. 14 is a sectional view along the line XIV-XIV in Fig. 13;

Fig. 15 is a view similar to Fig. 14 but showing a valve comprising a

valve housing secured to the valve cup assembly;

Fig. 16 is a sectional view similar to Fig.2 but with a valve actuator and a protective cap fitted thereto, the longitudinal cross-section being along a straight diametric line through the valve cup assembly shown in Fig. 1; and

Fig. 17 is a view to an enlarged scale of part of the view shown in Fig.

16 as indicated by arrow XVII.

Detailed Description

The drawings and following description relate to embodiments of the various aspects of the present invention by way of example only.

The drawings show an example of a fluid medium dispensing system 1 that includes a valve cup assembly 2 comprising a valve cup 3 and a locking ring 4. The assembly 1 also includes a container 5, and a valve 6 with a valve housing 7. Additional components of the system 1 include a valve actuator 8 and protective cap 9, as shown in Figs. 16 and 17. Typically, in use the inner region of the container 5 is pressurized to a pressure greater than atmospheric pressure. When a fluid medium is stored within the container 5 this pressure is typically around 7 bar, although the pressure is not limited to this value and may take any desired value limited only by regional or governmental restrictions. The valve 6 controls the egress of the fluid medium from the container 5 and is generally held in a fixed central position by the valve cup 3 such that when a force is applied to the valve 6 from a user via depression of the actuator 8, the valve 6 is opened. In this position, the pressure difference between the interior and the exterior of the container 5 causes the fluid medium to be distributed from the container 5 via the valve 6. The valve cup 3 is secured to the container 5 and retained in position by the locking ring 4 in a manner that resists the outward pressure exerted by the container's contents as is described in further detail below. To assist securement of the valve cup, the container 5 comprises a neck 10 defining an opening 11 in which the valve cup 3 is inserted. The neck 10 also includes a rim 12 that defines an annular lip 13.

In most cases, the valve cup 2 and the locking ring 3 will be formed from plastics materials so that they can be snap-fitted together and so that the valve cup 2 can be snap-fitted to the container 5, as is described in more detail below. Such plastics materials may be or include parts made from polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). The container 5 may be made from similar plastics materials but may also be made wholly or in part from aluminium. For example, in the illustrated embodiment at least the neck 10 of the container 5 is comprised of aluminium.

The valve cup 3 comprises a first part 14 that is located in the opening 11 of the container 4 and a second part 15 that covers the rim 12. Preferably, the first part 14 is a push-fit into the opening 11 and the second part 15 is formed with an inverted U-shaped profile in which the rim 12 of the neck 10 of the container 4 locates. Advantageously, the U-shaped second part 15 comprises at least one first protrusion 16 that extends radially inwards facing the neck 10 from the outer wall 17 of the second part 15. This protrusion 16 snap-fits over and beneath the lip 13 of the rim 12 of the neck 10. Preferably, however, a plurality of first protrusions 16 is spaced around the wall 17 and adjacent protrusions 16 are separated by axially extending slots 18 in the wall 17. The slots 18 split the wall 17 into a series of sections 19 and allow the second part 15 to flex radially outwards as it passes over the lip 13 during the snap-fitment of the valve cup 2 to the rim 12 of the neck 10. A seal 20 is provided between the valve cup 3 and the neck 10 of the container 5 (see Fig. 17). This preferably takes the form of a sealing ring or gasket 20 made from an elastomeric material such as, for example, rubber or silicone rubber. The seal 20 is located in the base of the inverted U-shaped second part 15 so that it covers the rim 12 of the container 5. The shape of the second part 15, the location of the sealing ring 20 and the snap-fitment of the valve cup 3 over the rim 12 ensures that a good seal is formed between the container 5 and the valve cup 3 that will enable the contents of the container 5 to remain pressurized. This is assisted by locking ring 4, which is provided to ensure that valve cup 3 remains in position. The locking ring 4 surrounds the second part 15 of the valve cup 3 around the neck 10 of the container 5 and is secured thereto as will now be described.

The locking ring 4 comprises an annulus that is initially secured to the valve cup 4 in a first position, as shown in Figs. 13 to 15, wherein it surrounds the outer wall 17 of the second part 15 of the valve cup 3. The locking ring 4 is located in this position during assembly of the fluid dispensing system 1 and is only moved to a second position, as shown in Figs 1, 2, 16 and 17 wherein it is made fast with the valve cup 3, when it is desired to lock the valve cup 3 to the container 5 during the final stages of the assembly. The locking ring 4 moves axially in a direction parallel to its longitudinal axis when moving from its first position into its second position and in both positions is snap-fitted to the valve cup 3, the snap-fitment in the second position being such that it is then difficult to separate it from the valve cup 3.

To enable the locking ring 4 to be secured to the valve cup 3 in its first position, the axial slots of the latter are bridged by portions of the wall 17 that define a series of second protrusions 21 that extend radially outwards. These protrusions 21 are engaged, preferably in a snap-fit manner, by at least one third protrusion 22 that extends radially inwards from the locking ring 4. The protrusion 22 may comprise an inwardly projecting, annular ring or, as shown in Figs. 9 to 12 a plurality of protrusions that are spaced around the interior of the locking ring 4. During assembly of the fluid dispensing system, the locking ring 4 is attached to the valve cup 3 by snap-fitment of the protrusion 22 or series of protrusions 22 on the locking ring 4 over the protrusions 21 on the valve cup 3. The locking ring 4 is then in a first position in relation to the valve cup 3, as shown in Figs. 14 and 15.

It will be appreciated from Figs. 14 and 15 that when the locking ring 4 is in its first position, it is capable of movement axially downwards relative to the valve cup 3 into a position shown in Figs 2, 16 and 17. The locking ring 4 is made fast to the valve cup 3 in this position by a snap-fitment. To this end, the wall 17 of the second part 15 of the valve cup 3 defines a plurality of undercuts 23. The undercuts 23 are spaced around the periphery of the wall 17 and separated by the axially extending slots 18.The undercuts 23 are also spaced axially from the second protrusions 21. When the locking ring 4 is moved axially downwards over the valve cup 3, the third protrusion or protrusions 22 on the locking ring 4 snap-fit into these said undercuts 23 and make the locking ring 4 fast to the valve cup 2.

The valve cup 3 and the locking ring 4 are preferably also provided with other complementary features that assist in securing the valve cup 3 to the container 5 to ensure a good sealing relationship between them. These features are now described.

First, the second part 15 of the valve cup 3 defines a series of recesses 24 that are spaced around its periphery between adjacent second protrusions 21. Preferably there are at least three and advantageously six such recesses that are evenly spaced around the periphery of the valve cup 3. The locking ring 4 defines a series of inwardly extending projections 25 that have a profile complimentary to that of the recesses 24 and that are adapted to locate within the recesses 24 when the locking ring 4 is in its second position. In addition, each of the projections 25 comprises a pair of nodules 26 that bear against an adjacent flat surface 27 defining its associated recess 24 of the valve cup 3. The nodules 26 therefore bear down on the second part 15 of the valve cup 3 so that the latter is gripped between the nodules 26 and the projections 22. The flat surfaces 27 are preferably arranged at right angles to the longitudinal axis of the valve cup 3 and locking ring 4. Also, the flat surfaces 27 comprise part of said first protrusions 16 that bear against the rim 12 of the container. This gives an exact flat surface contact for the lip 13 of the opening 11 to ensure a good seal between the valve cup 3 and the container 5.

The valve cup 3 and the locking ring 4 are preferably manufactured by injection moulding and their respective shapes have also been designed to make their production simple, economical and capable of "one-shot" moulding. In particular their shapes have been designed so that only top and bottom mould parts are needed with no radially moving mould components being required. To this end, in the valve cup 3 the first and second protrusions 16 and 21 respectively do not overlap one another in an axial direction parallel to a longitudinal axis of the valve cup. Similarly, in the case where a plurality of third protrusions 22 is provided on the locking ring 4, these also are arranged so that they do not overlap axially with the projections 25. This enables the protrusions 22 to jut out further than a single annular protrusion 22 would and therefore increases the securement of the locking ring 4 to the valve cup 3 especially when the former is in its second position. Also, all radially extending surfaces defining the protrusions 16, 21 and 22 the projections 25 also extend in an axial direction that is parallel to the longitudinal axis of the valve cup assembly comprising the connected valve cup 3 and locking ring 4. All of the foregoing features simplify the moulding process for manufacture of the valve cup 3 and the locking ring 4, which are therefore economical to produce

In use, the valve cup 3 is used to support and mount the valve 6 to the container 5 and the locking ring 4 is used to mount the valve actuator 8 for the valve 6. Both the valve cup 3 and the locking ring 4 have therefore also been designed for this purpose. The valve 6 is essentially of conventional construction and is mounted on the first part of the valve cup 14, which comprises a dome 28 with an interior recess 29 in which an enlarged diameter end portion 30 of the valve housing 7 is snap-fitted. Within the end portion 30 is a spring-loaded valve member 31 that is integrally formed with an outlet tube 32 for the contents of the container 5. The other end of the valve housing comprises an integrally-formed inlet tube 33 that projects downwards into the container 5. The outlet tube 32 passes through an annular sealing disc 34 and through an aperture 35 in the dome so that it projects from the first part 14 of the valve cup 3 where, after assembly of the dispensing system 1 it is engaged by the end of an outlet channel 36 in the valve actuator 8. The sealing disc 34 is preferably comprised of an elastomeric material and is retained at the mouth of the end portion 30 of the valve housing 7 in contact with the interior surface of the dome 28 by a moulded-in annular ridge 37 in the valve housing 5. In addition, the sealing disc 33 is clamped against the dome 28 by the spring-loaded valve member 31. When the valve member 31 is depressed against its spring loading 38, the pressurized contents of the container 5 are forced into the inlet tube 33, through the valve housing 7 and into the outlet tube 32 through two or more radial apertures 39 in the outlet tube 32. These apertures 39 are closed-off by the inner periphery of the sealing disc 34 when the valve member 31 is in contact with the sealing disc 34 but when the outlet tube 33 is depressed, the apertures 38 are also moved further into the body of the valve housing 7 away from the sealing disc 34 so that the pressurized contents of the valve housing 7 can penetrate through them into the outlet tube 32 and thence out of the valve 6, through the actuator 8 to the exterior of the system 1.

Although not a requirement of the invention, in most embodiments a bag 40 is attached to the inlet tube 33 of the valve 6 such that when the valve 6 is actuated the interior of the valve housing 7 is in fluid communication with the interior of the bag 40. The bag 40 may be secured to the inlet tube 33 by any suitable means such as adhesive, welding, or clamping. The combination of bag 40 and valve 6 in a fixed arrangement is generally referred to as a 'bag on valve' (BoV) construction. The bag 40 is preferably liquid, gas, or fluid impermeable. In use, the fluid to be dispensed by the system 1 is stored in the bag and a propellant is stored in the container to the exterior of the bag 40 so that the two fluids cannot mix. The container 5 is therefore filled with these fluids separately. The fluid to be dispensed from the bag 40 is inserted therein in an opposite direction to the path it will take on egressing from the container. However, the propellant must be inserted into the container 5 in a different manner. To enable this to take place, the area 41 of the dome 28 adjacent the aperture 35 is dished and the outlet tube 32 has an end portion or tip 42 that has an exterior diameter that is smaller than its diameter adjacent the radial apertures 39. Hence, if the valve 6 is opened to its widest extent by pushing the outlet tube 32 inwardly of the valve housing 7 to a maximum or near maximum extent, which typically requires a force greater than normal finger pressure on the outlet tube 32, then the end portion 42 of the tube 32 penetrates the aperture 35 opening up a passageway around it into the dome 28 through which a propellant may be pumped.

The locking ring 4 is adapted to mount the valve actuator 8 by provision of a series of outward projections 43 adjacent the projections 25. The outer surfaces of the projections 43 define an annulus over which a depending annular flange 44 of the actuator 8 may be either push-fitted or snap-fitted.

The assembly and filling of the fluid dispensing system will now be described.

The fluid dispensing system 1 is assembled in a series of stages that in practice are usually conducted by different manufacturers. In particular, a first company that makes the valve cup 3, locking ring 4 and valve 6 will combine these to make a valve cup assembly that is then transported to a second manufacturer that makes the fluid to be dispensed from the container 5. This second manufacturer will complete the manufacturing process by combining the valve cup assembly 2 with the container 5 and by filling the container.

In a first stage of assembly, a valve cup assembly 2 is formed by snap-fitting the locking ring 4 to the valve cup 3 such that the former is in its first position as described above. The valve 6 is then snap-fitted to the valve cup, having been pre- assembled to form a unit, as is conventional. During this pre-assembly process a bag 40 may be secured to the inlet tube 33.

In a second stage of assembly, the valve cup assembly 2 incorporating the valve 2 is secured to the container 5. This is accomplished by folding the bag 40 to reduce its footprint to less than the diameter of the opening 11 in the container 5 in order that the bag 40 and valve parts projecting from the valve cup assembly 3 may be inserted into the opening 11. The valve cup 3 is then positioned directly over the opening 11 and its first part 14 is push-fitted in the opening so that its second part 15 snap-fits over the lip 13 of the rim 12, as described above. Preferably, the dimensions of the first part 14 of the valve cup 3 relative to the size of the opening 11 are such that a force of around 196 N is required to push-fit the valve cup 3 into the neck 10 of the container 5. Once the valve cup 3 has been snap-fitted to the container 5 it is then secured in position by moving the locking ring 4 axially downwards into its second position wherein it is made fast with the valve cup 3, as also described above, the two snap-fitting together. The dispensing system 1 is now assembled and ready for filling.

Filling of the container is a two-stage process. First, the bag 40 is filled with the fluid to be dispensed by the system 1. Thereafter, the volume of the container between the outer surface of the bag 40 and the inner wall of the container is filled with a propellant. These stages are accomplished as follows. First, in known manner the outlet tube 32 is depressed to open the valve and thereby open the radial apertures 39. The fluid to be dispensed is then pumped down the outlet tube 32, through the apertures 39 into the valve housing 7 and thence into the bag 40 in an opposite direction to the path it will follow when egressing from the container 5. When the bag 40 is filled with an appropriate quantity of fluid, the valve 6 is allowed to close. In a separate operation, the valve 6 is opened to its greatest extent so that the end portion 42 of the tube 32 penetrates the aperture 35 and a propellant is then pumped into the container 5 around the outside of the bag 40 through the passage opened up through the dome 28 around the exterior of the outlet tube 32. Opening of the valve 6 also has the effect of reducing the pressure on the sealing disc 34. This enables the sealing disc 34 to flex and allow passage of the pressurized propellant through a gap between the disc 34 and the adjacent surface of the dome 28 and thence around the outside of the end portion 30 of the valve housing 7 and into the container 5. It will be appreciated that in normal operation of the valve 6 to dispense the contents of the bag 4, the sealing disc 34 does not flex away from the dome 38 because the interior pressure exerted on it by the fluid within the valve housing 7 presses it against the dome 28 even when the valve member 31 is open. During the filling operation, the pressure exerted on the sealing disc 34 from the exterior of the container 5 is greater than that exerted from the interior of the valve housing 7 so that the aforesaid gap can be created.

Once the container 5 has been charged with its contents, a final assembly stage can be carried out which involves the attachment of the actuator 8 to the locking ring 4 and the cap 9 to the actuator 8. The dispensing system 1 is then ready for sale. The actuator 8 is of conventional construction and will not be described in any detail but it will be appreciated that it comprises a movable press-button 45 on the top that pushes the outlet channel 36 downwards when depressed in order to actuate the valve 6.

It will be appreciated that the present invention provides a fluid medium dispensing system 1 comprising a valve cup assembly 2 with components that can be manufactured economically and efficiently and in a manner that simplifies the method of assembling the system 1 over conventional systems.

Claims

1. A fluid medium dispensing system comprising:

a valve;

2. A fluid medium dispensing system as claimed in Claim 1, wherein the locking ring moves axially in a direction parallel to its longitudinal axis when moving from its first position into its second position.

3. A fluid medium dispensing system as claimed in Claim 1 or Claim 2, wherein the second part of the valve cup is formed in an inverted U-shape in which the rim of the neck of the container is located.

4. A fluid medium dispensing system as claimed in Claim 3, wherein a seal is located in the base of the inverted U-shape between the valve cup and the rim of the neck.

5. A fluid medium dispensing system as claimed in any of Claims 1 to 4, wherein the locking ring is made fast to the valve cup in the second position by snap-fitment.

6. A fluid medium dispensing system as claimed in any of Claims 1 to 5, wherein the locking ring is secured to the valve cup in the first position by snap-fitment.

7. A fluid medium dispensing system as claimed in any of Claims 1 to 6, wherein the second part of the valve cup comprises at least one first protrusion that extends radially inwards on a first surface facing the neck of the container, which protrusion is snap-fitted over the rim of the neck.

8. A fluid medium dispensing system as claimed in Claims 7, wherein said first protrusion is snap-fitted over a lip defined by the rim of the neck.

9. A fluid medium dispensing system as claimed in Claim 7 or Claim 8, wherein a plurality of first protrusions is spaced around the second part of the valve cup, adjacent protrusions being separated by axially extending slots in the second part of the valve cup, which slots allow the second part to flex during the snap-fitment of the valve cup over the rim of the neck.

10. A fluid medium dispensing system as claimed in 9, wherein said axial slots are bridged by portions of the second part of the valve cup that define a series of second protrusions which extend radially outwards from the second part of the valve cup and which are engaged by at least one third protrusion that extends radially inwards from the locking ring.

11. A fluid medium dispensing system as claimed in Claim 10, wherein a plurality of third protrusions is provided that are spaced around the interior of the locking ring.

12. A fluid medium dispensing system as claimed in Claim 10, wherein said at least one third protrusion comprises an inwardly projecting, annular ring.

13. A fluid medium dispensing system as claimed in any of Claims 10 to 12, wherein the first protrusions and the second protrusions do not overlap one another in an axial direction parallel to a longitudinal axis of the valve cup.

14. A fluid medium dispensing system as claimed in any of Claims 10 to 13, wherein said at least one third protrusion of the locking ring is snap-fitted over the second protrusions of the valve cup to secure the locking ring to the valve cup in its first position.

15. A fluid medium dispensing system as claimed in Claim 14, wherein an outer wall of the second part of the valve cup defines a plurality of undercuts that are spaced around its periphery and separated by the axially extending slots, and that are spaced axially from the second protrusions, said at least one third protrusion of the locking ring snap-fitting into said undercuts to make the locking ring fast to the valve cup in its second position.

16. A fluid medium dispensing system as claimed in any of Claims 10 to 15. wherein the second part of the valve cup defines a series of recesses spaced around its periphery between adjacent second protrusions.

17. A fluid medium dispensing system as claimed in Claim 16, wherein the series of recesses comprises at least three and preferably six recesses evenly spaced around the periphery of the valve cup.

18. A fluid medium dispensing system as claimed in Claim 16 or Claim 17, wherein the locking ring defines a series of inwardly extending projections that are adapted to locate within the recesses defined by the valve cup when the locking ring is in its second position.

19. A fluid medium dispensing system as claimed in Claim 18, wherein the inwardly extending projections each define a flat surface that bears against an adjacent flat surface defining its associated recess of the valve cup.

20. A fluid medium dispensing system as claimed in Claim 19, wherein said adjacent flat surfaces defining said recesses comprise part of said first protrusions that bear against the rim of the neck of the container.

21. A fluid medium dispensing system as claimed in any of Claims 8 to 20, wherein all radially extending surfaces defining said protrusions and said projections also extend in an axial direction that is parallel to a longitudinal axis of a valve cup assembly comprising the connected valve cup and locking ring.

22. A fluid medium dispensing system as claimed in any of Claims 1 to 21, wherein the first part of the valve cup is push-fitted into the neck of the container.

23 A fluid medium dispensing system as claimed in any of Claims 1 to 22, wherein the valve comprises a valve housing that is snap-fitted into the first part of the valve cup.

24. A fluid medium dispensing system as claimed in any of Claims 1 to 23, wherein the locking ring is adapted for securement to an actuator for the valve.

25. A fluid medium dispensing system as claimed in any of Claims 1 to 24, wherein the valve cup and the locking ring are formed from plastics material, preferably polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

26. A fluid medium dispensing system as claimed in any of Claims 1 to 25, wherein at least the neck of the container is comprised of aluminium.

27. A valve cup assembly comprising a valve cup and a locking ring for a fluid medium dispensing system, the valve cup comprising a first part adapted to support a valve and to locate in an opening defined by a neck of a container and a second part adapted to cover a rim of the neck defining the opening; and

the locking ring adapted to be secured to the valve cup; characterized in that the locking ring is secured to the valve cup in a first position surrounding the second part of the valve cup and is movable from the first position into a second position wherein it is made fast to the valve cup.

28. A valve cup assembly as claimed in Claim 27, wherein the locking ring moves axially in a direction parallel to its longitudinal axis when moving from its first position into its second position.

29. A valve cup assembly as claimed in Claim 27 or Claim 28, comprising a valve with a valve housing that is snap-fitted to the first part of the valve cup.

30. A valve cup assembly as claimed in any of Claims 27 to 29, wherein the second part of the valve cup is formed in an inverted U-shape in which a seal is located.

31. A method of assembling a fluid dispensing system for dispensing a fluid medium stored under pressure, the method including:

providing a container, the container being suitable for storing a fluid medium under pressure and comprising a neck that defines an opening; providing a valve cup comprising a first part adapted to support a valve and to locate in the opening of the container and a second part adapted to cover a rim of the neck;

providing a locking ring adapted to be secured to the valve cup in a first position surrounding the second part of the valve cup and that is capable of movement relative to the valve cup from the first position into a second position wherein it is made fast to the valve cup;

positioning the valve cup at the opening of the container and push- fitting it in the opening so that the first part is located in the opening and the second part covers the rim;

charging the internal volume of the container.

32. A method as claimed in Claim 31, wherein prior to securing the valve housing to the first part of the valve cup, the method comprises the additional steps of providing a bag, attaching the valve to an opening of the bag, and fluidly sealing the bag to the valve, the bag being subsequently inserted into the container immediately prior to the valve cup being push- fitted in the opening of the container.

33. A method as claimed in Claim 32, wherein the internal volume of the container is pressurized with a propellant and the bag is filled with the fluid medium to be dispensed after the locking ring has been moved into its second position.

34. A method as claimed in Claim 31, wherein the internal volume of the container is charged with the fluid medium to be dispensed and a propellant is added to the contents of the container after the locking ring has been moved into its second position.

35. A method as claimed in any of Claims 31 to 34, wherein the valve cup is push-fitted into the neck of the container with a force of around 196 N.

36. A method as claimed in any of Claims 31 to 35, wherein prior to push- fitment of the valve cup into the neck of the container, a seal is provided and located in the second part of the valve cup such that after push-fitment of the valve cup in the neck of the container it is located between the second part of the valve cup and the rim of the neck.

37. A fluid medium dispensing system as claimed in any of Claims 31 to 36, wherein the locking ring is secured to the valve cup in its first position by snap-fitment.

38. A method as claimed in any of Claims 31 to 37, wherein the locking ring is made fast to the valve cup in its second position by snap-fitment.

39. A method as claimed in any of Claims 31 to 38, wherein the second part of the valve cup snap-fits over a lip defined by the rim of the neck of the container when the valve cup is push-fitted into the neck.

40. A method as claimed in any of Claims 31 to 39, wherein after charging of the internal volume of the container with the fluid medium to be dispensed, a valve actuator is secured to the locking ring.