WO1991010607A1

WO1991010607A1 - Atomising valve assemblies

Info

Publication number: WO1991010607A1
Application number: PCT/GB1991/000086
Authority: WO
Inventors: Stephen T. Dunne; Terence E. Weston; Douglas A. Emmott; Anthony W. King
Original assignee: Dunne Miller Weston Limited
Priority date: 1990-01-20
Filing date: 1991-01-18
Publication date: 1991-07-25
Also published as: AU7221291A; GB9001348D0

Abstract

In an aerosol dispenser, a valve assembly comprises a generally conventional arrangement of a valve body (1) in a cup (4), a valve stem (9) in the valve body (1), and an actuator body (20) for depressing the valve stem (9) against a spring (10) to release atomised liquid through an outlet passage (21) and an atomising orifice (26). In addition to such conventional parts, a variable volume expansion chamber (30) is provided in the actuator body (20), and this communicates with the outlet passage (21). Upon shut-off, at the end of a dispensing operation, the volume of the expansion chamber (30) expands, to allow the expansion of foam (liquid/gas mixture) trapped at least in the outlet passage (21). Since the foam is allowed to expand in this controlled manner, spitting of liquid droplets at shut-off is prevented or inhibited.

Description

ATOMISING VALVE ASSEMBLIES

This invention relates to atomising valve assemblies.

Atomising valve assemblies are widely used - for example, in aerosol dispensers. Many aerosol dispensers suffer from product spitting at valve shut-off. A reason for this is that un-expanded foam (liquid/gas mixture) trapped between a valve and an atomising orifice or insert expands slowly down to atmospheric pressure at too low a velocity to cause proper atomization. The foam is at a pressure above atmospheric because the size of the actuator orifice or insert is relatively small, which leads to a relatively high pressure behind it to achieve the desired product flow rate.

With liquefied gas propellants, such spitting can occur when relatively low quantities of propellant are used. When high quantities are used, such as in most hair-spray and deodorants, any trapped foam usually has enough latent energy of evaporation for expansion to lead to proper atomization.

The problem of spitting at shut-off tends to be more pronounced with certain permanent gas propellants, and in particular with CO₂, which is dissolved in the liquid product but does not expand violently enough to cause proper atomization of the trapped foam. The same problem can occur with nitrogen powered aerosols when used with microtap valves.

Preferred embodiments of the present invention aim to provide atomising valve assemblies which prevent or minimise spitting at shut-off. According to a first aspect of the present invention, there is provided an atomising valve assembly comprising:

an outlet passage for the flow therethrough of a liquid/gas mixture to be atomised;

atomising means located in or adjacent said outlet passage, to atomise liquid/gas mixture flowing through the outlet passage;

valve means arranged selectively to connect and disconnect the outlet passage to and from a supply of liquid/gas mixture to be atomised;

an expansion chamber arranged to communicate with the outlet passage, at least when the valve assembly is in a non-dispensing condition; and

means for increasing the volume of the expansion chamber upon the valve means disconnecting the outlet passage from a supply of liquid/gas mixture to be atomised.

Preferably, said expansion chamber and means for increasing the volume thereof comprise an interengaging piston and cylinder arranged for relative sliding movement.

Preferably, resilient bias means is provided for urging the means for increasing the volume of the expansion chamber into a position in which the volume of the expansion chamber is a maximum. Preferably, said resilient bias means comprises a spring.

There may be provided an inlet passage to receive a liquid/gas mixture to be atomised from a supply of the liquid/gas mixture, and means connecting said inlet passage with said outlet passage.

The expansion chamber may be disposed between said inlet passage and said outlet passage.

Said valve means may be disposed between said inlet passage and said outlet passage.

Such an assembly may include a further valve means disposed between said inlet passage and a supply chamber or reservoir of liquid/gas mixture to be atomised.

Alternatively, the first-mentioned valve means may be disposed between said inlet passage and a supply chamber or reservoir of liquid/gas mixture to be atomised.

Said inlet passage may be formed in the stem of a valve member which forms part of said valve means or further valve means.

When an atomising valve assembly as above includes resilient bias means for urging the means for increasing the volume of the expansion chamber into a position in which the volume of the expansion chamber is a maximum, said valve means and/or said further valve means may be resiliently biassed into a closed position, and the relative timing of the opening of the or each such valve means and the increase in volume of the expansion chamber may be determined by the relative values of the respective resilient biasses.

The atomising valve assembly may be adapted for use in a vertically actuating aerosol dispenser.

The invention extends to an atomising device provided with an atomising valve assembly as above, in accordance with the first aspect of the invention.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:

Figures la and lb are partial sectional views of one example of an aerosol dispenser provided with an example of an atomising valve assembly which embodies the invention, Figure la showing a valve and actuator in a closed position and Figure lb showing the valve and actuator in an open position;

Figures 2a and 2b show a device similar to that of Figures la and lb, but with an actuator spring located in an alternative position;

Figures 3a and 3b show a device similar to that of Figures 1 and 2 but with an extra seal forming a shut-off valve in the actuator; Figures 4a and 4b show a device similar to that of Figure 3 but with seals located alternatively; and

Figure 5 shows a device similar to that of Figure 4 but with a conventional aerosol valve eliminated.

In the figures, like reference numerals denote like or corresponding parts.

Figures la and lb show a convention aerosol valve modified as a microtap type valve, with a conventional actuator being replaced by an alternative actuator to form an embodiment of the invention. Apart from this modification, the valve shown is generally of the type described in our Published Patent Application No WO 90/05580, to which the reader's attention is directed.

A valve body 1 is connected to a dip tube 2 and mounted in a conventional 25mm cup 4, with the interposition of a seal 3. A valve stem

9 and spring 10 are held in position by the cup 4 and body 1. A gas bleed 5, a liquid restrictor 6 and two foaming chokes 7 and 8 are sized and positioned relative to one another for optimum operation of the valve.

Normally, an actuator comprising a body 20, outlet passage 21, swirl chamber 25 and insert 26 would sit on the valve stem 9. The valve would be operated by pressing the actuator body 20 down to connect a cross-hole 11 in the stem 9 with a chamber 12 which is full of a mixture of liquid and gas. This mixture is then forced up the stem 9 as a foam and out through the insert 26, where it is atomised. The illustrated embodiment of the invention comprises, in addition to conventional actuator components of body 20, outlet passage 21, swirl chamber 25 and insert 26, extra parts of a spring 23, an expansion cavity or chamber 30, a seal 24 and a stop 31. The actuator body 20 is allowed to move on the valve stem 9 and is biased into the closed position of Figure la by the spring 23 against a stop (not shown). The seal 24 seals the expansion chamber 30 from the atmosphere.

When the actuator body 20 is depressed by finger pressure, the body 20 travels downwards until the stop 31 comes up against the valve stem 9 and reduces the expansion chamber 30 to its smallest volume. Further pressure pushes the stem 9 downwards so that the stem cross-hole 11 is released from the seal 3 and opened to the pressurised container, thereby filling the stem 9, cavity 21 and swirl chamber 25 with a foam of the liquid/gas mixture at a higher pressure than atmospheric, due to the restrictive nature of the spray insert 26. Figure lb shows the valve in the ON position.

When finger pressure is rapidly released, the valve closes as the cross- hole 11 is closed by the seal 3, and immediately after this, the expansion chamber 30 increases in volume due to the actuator body 20 being urged upwardly by the spring 23. This absorbs the expansion of the foam trapped in the stem 9, outlet passage 21 and swirl chamber 25. The seal 24 could be alternatively located in an annular recess formed on the stem 9, rather than in the illustrated annular recess located in the body 20.

If the expansion chamber 30 were not provided, the foam which is trapped in between the valve stem cross-hole 11 and the actuator insert 26 upon shut-off would tend to cause spitting. This foam can be divided into two separate components: that in the stem 9 cavity and that in the outlet passage 21. The stem 9 cavity is usually the larger of the two.

In the embodiment of Figures la and lb, both foam components are allowed to expand into the enlarged cavity 30 formed when the actuator is released. In this embodiment, the actuator is mounted on the valve stem 9 as in conventional systems but allowed to slide relative to the stem 9 to increase the volume available for foam expansion at shut-off. The spring 23 ensures that the actuator returns to the off position and the seal 24 prevents leakage down the stem.

It will be appreciated that the top of the valve stem 9 and the actuator body 20 effectively provide an interengaging piston and cylinder, to vary the volume of the expansion chamber 30.

Figures 2a and 2b show an alternative arrangement where the spring 23 is now mounted within the expansion cavity 30. In this arrangement, the spring 23 is preferably weaker than the valve spring 10, to ensure that the expansion cavity 30 closes before the valve is opened. Otherwise, the embodiment of Figures 2a and 2b functions in a manner similar to that of Figures la and lb.

In another embodiment (not shown), an expansion chamber may be effectively provided by an increased volume formed by a bellows arrangement formed as part of the stem 9. When finger pressure is released from the actuator, the bellows expands, creating sufficient volume for the foam to expand into. Figures 3a and 3b show an alternative embodiment where at shut-off only the foam in the outlet passage 21 and so-called swirl chamber 25 can expand through the insert 26, and hence only foam trapped here and not in the stem 9 needs to be sucked into the expansion cavity 30, to avoid spitting.

A second seal 35 isolates the stem 9 from the oudet passage 21. In this way, the expansion cavity 30 need only accommodate the foam trapped in the outlet passage 21 and the swirl chamber 25. A spring locator 36 is used to increase the expansion ratio of the expansion cavity 30 by minimising its volume when the valve is in the ON position as shown in Figure 3b. Depression of the actuator 20 connects a cross-hole 38 and annular distribution groove 39 to the oudet passage 21. The spring 10 should be weaker than spring 23 in order that the valve closes after the anti-spit device and not before, as otherwise misuse could lead to the device not functioning. It is also preferable that the spring 23 is pre-compressed.

The embodiment of Figures 3a and 3b functions in a generally similar manner to that of Figures la and lb, apart from the difference mentioned above. The expansion chamber 30 communicates permanently with the outlet passage 21 via the annular space between the valve stem 9 and the cylinder in which it engages - there being no seals above the seal 35. The annular distribution groove 39 ensures communication between the outlet passage 21 and cavity within the valve stem 9, irrespective of the angular orientation of the valve stem 9.

Figures 4a and 4b show an embodiment very similar to that of Figures 3a and 3b, but with the seals 24 and 35 located in annular grooves on the stem 9 instead of in the body 20. The seals 24 and 35 could also be moulded as part of the stem 9.

Figure 5 shows an arrangement where the conventional valve has been eliminated with the valve stem 9 and its respective valve body 1 being replaced by a fixed stem 40. The stem 40 is sealingly held by a cup 41 and seal 42. All other components are as shown in Figures 3a and 3b. Since this embodiment has in effect an open/shut valve formed by the seal 35, stem 40 and actuator body 20, there is no need for an additional conventional valve. To prevent the actuator 20 being pushed off the stem 40, the stem 40 has an undercut 46 in which a pin 45 is located. This arrangement also allows the spring 23 to be pre-compressed and an arrangement such as the undercut 46, pin 45 and pre-compressed spring 23 are all applicable to the previous embodiments described above.

All of the above described and illustrated embodiments are of a vertically actuating aerosol dispenser - that is, an aerosol dispenser in which a liquid to be dispensed is held within a container together with a propellant gas (optionally liquified), and in which the dispenser is usually held upright and actuated by a downward finger pressure on an actuator body such as 20, in order to open the relevant valve(s) and allow the liquid to be dispensed in atomised form.

However, it is to be understood that the invention may be applied to all other suitable types of atomising devices.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiments). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. An atomising valve assembly comprising:

2. An atomising valve assembly according to claim 1, wherein said expansion chamber and means for increasing the volume thereof comprise an interengaging piston and cylinder arranged for relative sliding movement.

3. An atomising valve assembly according to claim 1 or 2, wherein resilient bias means is provided for urging the means for increasing the volume of the expansion chamber into a position in which the volume of the expansion chamber is a maximum.

4. An atomising valve assembly according to claim 3, wherein said resilient bias means comprises a spring.

5. An atomising valve assembly according to any of the preceding claims, wherein there is further provided an inlet passage to receive a liquid/gas mixture to be atomised from a supply of the liquid/gas mixture, and means connecting said inlet passage with said outlet passage.

6. An atomising valve assembly according to claim 5, wherein the expansion chamber is disposed between said inlet passage and said outlet passage.

7. An atomising valve assembly according to claim 5 or 6, wherein said valve means is disposed between said inlet passage and said outlet passage.

8. An atomising valve assembly according to claim 7, including a further valve means disposed between said inlet passage and a supply chamber or reservoir of liquid/gas mixture to be atomised.

9. An atomising valve assembly according to claim 5 or 6, wherein said valve means is disposed between said inlet passage and a supply chamber or reservoir of liquid/gas mixture to be atomised.

10. An atomising valve assembly according to any of claims 5 to 9, wherein said inlet passage is formed in the stem of a valve member which forms part of said valve means or further valve means.

11. An atomising valve assembly according to claim 3 or to any of claims 4 to 10 as appendant thereto, wherein said valve means and/or said further valve means is/are resiliently biassed into a closed position, and the relative timing of the opening of the or each such valve means and the increase in volume of the expansion chamber is determined by the relative values of the respective resilient biasses.

12. An atomising valve assembly according to any of the preceding claims, being adapted for use in a vertically actuating aerosol dispenser.

13. An atomising device provided with an atomising valve assembly according to any of the preceding claims.