GB2212222A

GB2212222A - Dispensing apparatus

Info

Publication number: GB2212222A
Application number: GB8726282A
Authority: GB
Inventors: David John Howlett
Original assignee: Bespak PLC
Current assignee: Consort Medical PLC
Priority date: 1987-11-10
Filing date: 1987-11-10
Publication date: 1989-07-19
Also published as: GB8726282D0

Abstract

Dispensing apparatus (1) comprises a valve (2) defining a chamber (8) and having an inlet duct (15) communicating with the chamber, a tube (3) having an end portion (19) mating with the inlet duct for the delivery of a first fluid to the chamber, and tap means (23) for admitting a second fluid to the chamber wherein the outer surface of the end portion and the inner surface of the duct cooperate to define at least one passageway (23) through the inlet duct facilitating the flow of the second fluid to thereby constitute the tap means. A vapour tap is thereby formed with minimal complexity to the valve moulding operation. <IMAGE>

Description

DISPENSING APPARATUS This invention relates to dispensing apparatus particularly but not exclusively for use in pressurised dispensing containers.

It is known for dispensing apparatus for pressurised dispensing containers to comprise a valve defining a chamber with an inlet duct communicating with the chamber. The valve is generally located in the head space of such a container and the container is filled such that a liquid to be dispensed occupies the lower part of the container whilst the upper part of the container defines a head space occupied by propellant vapour or gas.

It is also known to provide a tap often referred to as a vapour tap which admits a quantity of propellant fluid from the head space into the chamber during a dispensing operation such that a mixture of propellant and the product liquid is dispensed so as to provide an improved quality of aerosol spray when dispensed through a suitable nozzle.

A problem with such vapour taps is that in providing one or more passageway constituting the vapour tap the moulding operation is increased in complexity with subsequent increase in cost.

According to the present invention there is disclosed dispensing apparatus comprising a valve defining a chamber and having an inlet duct communicating with the chamber, a tube having and end portion mating with the inlet duct for the delivery of a first fluid to the chamber, and tap means for admitting a second fluid to the chamber wherein the outer surface of the end portion and the inner surface of the duct cooperate to define at least one passageway through the inlet duct facilitating the flow of the second fluid to thereby constitute the tap means.

Preferably the duct surface includes at least one groove extending longitudinally with respect to the duct along at least that portion of the duct surface contacted by the end portion to thereby form a corresponding number of the passageways.

An advantage of such an arrangement is that minimal moulding complexity is associated with the provision of grooves in the duct surface.

Preferably the duct includes gripping means for~ resisting withdrawal of the tube.

Conveniently the gripping means comprises an annular barb projecting radially inwardly of the duct surface so as to indent and grip the tube.

Advantageously the duct includes a frusto conically tapering throat portion which tapers in a direction towards the chamber to a cross section less than the undeformed cross section of the tube and the duct further includes a cylindical portion of greater cross section than the undeformed cross section of the tube, the cross section of the duct being radially stepped at the interface between the tapered and the cylindical portions to thereby constitute the barb.

Conveniently the or at least one of the grooves is of rectangular cross section and is of uniform radial extent as viewed in axial projection with respect to the duct axis.

An advantage of such an arrangement is that the grooves can therefore be formed by an axially directed moulding tool.

Preferably the valve is a dispensing valve for a pressured dispensing container of the type containing a liquid product located in a-lower part of the container and constituting the first fluid and a propellant vapour or gas constituting the second fluid and located in an upper part of the container and wherein the tube is a dip tube having a lower end normally immersed in the liquid product, the valve being located in the upper part of the container such that in use the passageways admit propellant vapour or gas to the flow of liquid dispensed.

A particular embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings of which Figure 1 is a sectional elevation of a pressurised dispensing container including a valve and dip tube in accordance with the present invention, Figure 2 is a plan view of the valve of Figure 1, Figure 3 is a sectional elevation of the body of the valve of Figure 2 and Figure 4 is an end view of the inlet duct of the valve of Figure 3.

In Figure 1 dispensing apparatus 1 comprises a valve 2 and a tube 3.

The valve 2 is mounted on a pressurised dispensing container 4 and is held in place by a crimped cup 5 such that a dispensing valve stem 6 projects through an aperture in the cup.

The valve stem 6 cooperates with an elastomeric seal 7 to provide valve action for discharging fluid from a chamber 8 of square internal cross section defined within the valve 2 in a conventional manner, the stem being spring biased into a closed position of the valve by means of a coil spring 9 located within the chamber.

The container 4 is shown in its normal orientation for dispensing use in which the valve 2 is uppermost and is located within a head space 10 occupied by propellant vapour. A lower part 11 of the container 4 is occupied by a product liquid 12. The dip tube 3 has a lower end 13 immersed in the liquid and an upper end 14 received in mating engagement within an inlet duct 15 of the valve 2. The inlet duct 15 extends downwardly in communication with the chamber 4 at the opposite end of the chamber from the projecting valve stem 6.

The inlet duct 15 has a conically tapered lower portion 16 and a generally cylindrical upper portion 17 which are joined at a step 18 which is in the form of a barb since the upper portion is of greater diameter than the lower portion at the interface between the upper and lower portions.

The upper portion 17 is not truly cylindrical but has a slight taper in an upward direction as a means of aiding mould release during the process of moulding the valve 2. The tube 3 is formed of plastics material (plasticised polypropylene) and as shown in Figure 1 has an upper end portion 19 which is received within the inlet duct 15 such that the upper end portion extends above the barb defined by the step 18, the upper end portion being indented by the barb at this point and gripped against withdrawal from the inlet duct.

Three grooves 20 are formed in the lower portion 16 of the duct 15 and extend axially from the mouth 21 of the inlet duct to the step 18. The grooves 20 are circumferentially spaced as seen in Figure 4 and are of rectangular cross section, each groove having a bottom surface 22 which extends at a constant radius-with- respect to the duct axis. This is a convenient shape to mould since it can be formed by axial movement of a mould tool. Three passageways 23 are defined by the groove surfaces and the tube 3 to thereby provide communication between the headspace and the chamber via the inlet duct 15, a path for vapour or gas thereby being provided outside of the tubes but within the duct 15.

In use to dispense the product liquid the valve stem 6 is depressed so as to move downwardly into the chamber 8 to an extent which is sufficient to operate the valve 2 thereby discharging pressurised fluid from within the chamber so as to be discharged through the stem 6.

As fluid is dispensed from the chamber a pressure difference is established between the chamber and the interior of the container 4 which is pressurised by action of the propellant vapour in the head space 10. A flow of liquid is then forced to flow from the lower part 11 of the container through the dip tube 3, through the inlet duct 15 and into the chamber 8 from which it is dispensed through the valve stem 6.

At the same time propellant vapour is forced to flow through the passageways 23 from the head space 10 into the chamber 8 such that propellant vapour is mixed with the flow of product liquid.

The passageways 23 thereby constitute a vapour tap allowing improved quality of aerosol dispensing of the product liquid.

Alternative embodiments of the invention are envisaged in which an inlet duct having no grooves cooperates with a grooved dip tube to define passageways. The invention may also have application in pump dispensers where vapour/air and liquid are drawn by suction into the chamber rather than by positive pressure applied by propellant vapour/air.

The invention may also have application in metering valve dispensers where a more complex valve arrangement is included but nevertheless liquid enters the chamber through a dip tube and inlet duct arrangement.

Claims

1. Dispensing apparatus comprising a valve defining a chamber and having an inlet duct communicating with the chamber, a tube having and end portion mating with the inlet duct for the delivery of a first fluid to the chamber, and tap means for admitting a second fluid to the chamber wherein the outer surface of the end portion and the inner surface of the duct cooperate to define at least one passageway through the inlet duct facilitating the flow of the second fluid to thereby constitute the tap means.

2. Dispensing apparatus as claimed in claim 1 wherein the duct surface includes at least one groove extending longitidinally with respect to the duct along at least that portion of the duct surface contacted by the end portion to thereby form a corresponding number of the passageways.

3. Dispensing apparatus as claimed in either of claims 1 and 2 wherein the duct includes gripping means for resisting withdrawal of the tube.

4. Dispensing apparatus as claimed in claim 3 wherein the gripping means comprises an annular barb projecting radially inwardly of the duct surface so as to indent and grip the tube.

5. Dispensing apparatus as claimed in claim 4 wherein the duct includes a frusto conically tapering throat portion which tapers in a direction towards the chamber to a cross section less than the undeformed cross section of the tube and the duct further includes a cylindical portion of greater cross section than the undeformed cross section of the tube, the cross section of the duct being radially stepped at the interface between the tapered and the cylindical portions to thereby constitute the barb.

6. Dispensing apparatus as claimed in any of claims 2 to 5 wherein the or at least one of the grooves is of rectangular cross section and is of uniform radial extent as viewed in axial projection with respect to the duct axis.

7. Dispensing apparatus as claimed in any preceeding claim wherein the valve is a dispensing valve for a pressurised dispensing container of the type containing a liquid product located in a lower part of the container and constituting the first fluid and a propellant vapour or gas constituting the second fluid and located in an upper part of the container and wherein the tube is a dip tube having a lower end normally immersed in the liquid porduct, the valve being located in the upper part of the container such that in use the passageways admit propellant vapour or gas to the flow of liquid dispensed.

8. Dispensing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.