Valves for packaging containers

Details Valves for packaging containers Valves for packaging containers

2000-02-22

2001-08-14

Shaver, Kevin (Department: 3754)

Dispensing

Outlet element operated by pressure of contents

Spring form, resilient or compressible flow controller or...

Reexamination Certificate

active

06273305

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to self-closing valves for packaging containers, that is to say, valves which open in response to an elevated pressure of the liquid product in a packaging container, and which close again automatically and in a self-sealing manner when the pressure has subsequently been reduced to below ambient pressure.
Self-closing valves are well known in the patent literature, and examples of them are disclosed in published patent specifications EP 0545678, EP 0395380, FR 996998, U.S. Pat. No. 2,758,755, U.S. Pat. No. 2,175,052 and WO 97/05055 amongst many others. Self-closing valves have been proposed for use with a wide variety of liquid foods e.g. ketchups, and household products e.g. washing-up liquids.
The requirements of a self-closing valve to dispense product in a controlled manner when required and to automatically reseal after dispensing tend to conflict with one another insofar as the configuration of the valve is concerned. Amongst the other requirements which may impose further restraints on the valve design are the need for the valve head to adopt an advanced position for the dispensing operation, and for the valve to be capable of being readily sealed, against inadvertent operation or dribbling, by a travel head with which it is engaged up to the point of use. In addition, for cleanliness of operation it may be preferred for the valve head at all times to stand proud of the closure in which the valve is mounted.
A further desirable characteristic of a self-closing valve is that it is capable of venting the container headspace in response to small negative pressures which are generated there after dispensing. This is of particular concern where the containers are plastics squeeze bottles which for economy have a reduced wall thickness, e.g. 0.4 mm, and a correspondingly reduced ability to resile when they are allowed to relax. Without the ability of the valve to vent, such a container may be subject to unsightly inward panelling and crumpling of its body wall. Satisfactory venting and reclosure of a self-closing valve in response to negative pressures of 1 kPa or less is therefore desirable.
In attempting to meet the various requirements imposed upon them known self-closing valves have been made from a substance having advanced physical properties, in particular of flexibility and resilience. Liquid silicon such as is marketed by Bayer under the trade name Silopren has been particularly preferred for this purpose, although thermoplastic elastomers have also been contemplated.
These materials are expensive in comparison with the thermoplastic resin materials usually used for packaging, and for cost savings it is therefore desirable, as a further objective, to minimise the material weight of the valve.
SUMMARY OF THE INVENTION
The present invention seeks to provide a self-closing valve which satisfies the above requirements to at least a substantial degree. In accordance with the invention from one aspect thereof a self-closing valve for a packaging container comprises (a) a marginal region by which the valve may be peripherally secured to a housing so as to close an opening in the same, (b) a valve head having an openable dispensing aperture and movable axially in relation to the marginal region between an advanced, dispensing position in which the aperture is open and product may be dispensed under pressure and a retracted, inoperative position in which the aperture is closed and the valve head forms a seal and (c) a connecting wall which is imperforate and flexible and comprises first and second portions serially arranged between the marginal region and the valve head and joined together at a V-form elbow, the first portion extending inwardly from the marginal region to the elbow, the second portion extending generally axially from the elbow to peripheral attachment with the valve head, and the connecting wall being of increased wall thickness at the elbow whereby during operation of the valve the elbow may keep its identity and act resiliently as a spring for returning the valve head to its retracted position.
The first portion of the connecting wall may be substantially frustoconical when the valve head is in each of its retracted and advanced positions, extending inwardly and downwardly away from the valve head in its retracted position, and extending inwardly and upwardly towards the valve head in its advanced position. In this way the connecting wall may be arranged to give a bistable operating characteristic to the valve at a positive pressure of typically 3 to 5 kPa.
As an alternative to providing bistable operation for the valve, the first portion of the connecting wall may be arranged to move from a substantially frustoconical, inwardly and downwardly extending unstressed position to a substantially plane, metastable position as the valve head moves between its retracted and advanced positions. In this way it may be arranged to provide substantial assistance to the elbow to return the valve head resiliently to its retracted position. DE 196 13 130 discloses a self-closing valve in accordance with the precharacterising part of claim 1. The valve has a thickened portion of its connecting wall designed for variously acting as a passive abutment with the closure structure and with a further part of the connecting wall. In particular, the connecting wall of the valve of DE 196 13 130 has no V-form elbow capable of acting as a spring to return the valve head to its retracted position.
In accordance with a second aspect thereof a self-closing valve for a packaging container comprises (a) a marginal region by which the valve may be peripherally secured to a housing so as to close an opening in the same, (b) a valve head having a dispensing aperture formed in a central part thereof and openable to allow product to be dispensed under pressure, the valve head being self-closable to form a seal when the product pressure subsequently abates and (c). a connecting wall which is imperforate and flexible and connects the marginal region with the valve head, characterised in that the connecting wall has a substantially cylindrical first part and an inturned, substantially radially extending second part by which the first part is attached to the valve head periphery, the thickness of the valve head reducing from the valve head periphery inwardly towards the dispensing aperture, and the second part of the connecting wall having a thickness which is at most one third of the thickness of the valve head periphery and such that during operation of the valve the second part may act as a living hinge, with substantially no flexural stiffness.
Preferably, the at-rest position of the valve in use is the same as the position in which it is manufactured.
In conjunction with the substantial lack of flexural stiffness of the second part of the connecting wall, this feature assists venting.
In order that the invention may be more fully understood, self-closing valves embodying the invention will now be described, by way of example, with reference to the accompanying drawings. Of the drawings:


REFERENCES:
patent: 5213236 (1993-05-01), Brown et al.
patent: 5339995 (1994-08-01), Brown et al.
patent: 5377877 (1995-01-01), Brown et al.
patent: 5409144 (1995-04-01), Brown
patent: 5439143 (1995-08-01), Brown et al.
patent: 5839614 (1998-11-01), Brown

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