GB2051017A - Stopper for a container - Google Patents

Abstract

A stopper adapted to allow gases to enter and leave a container whilst preventing liquid escaping from the container, comprises an axial opening in which is received an element (8) which defines a sinuous fluid path closed intermediate its end by a membrane (13) permeable to gas but impermeable to liquid. The membrane is clamped between two parts (9a, 9b) hinged together, Fig. 3 (not shown), to form the element, holes (12a, 12b) in these parts being arranged so that liquid drains naturally from the membrane and the membrane is not directly accessible from the outside of the stopper. <IMAGE>

Description

SPECIFICATION Stopper for a container The present invention relates to a stopper for a container.

There are numerous cases in which it is necessary for the interior volume of a package, such as a can, box or other container, needs to communicate with the surrounding atmosphere without any liquid contained in the container being able to escape.

This problem arises especially in the case of containers containing liquid capable of giving offvapours which must be released into the atmosphere so as to prevent excess pressure in the interior of the container, or again in respect of containers containing a liquid and a certain volume of air or other gas which must be capable of freely expanding or contracting with the liquid contents of the container.

Numerous valve, diaphragm or other systems have been used to resolve this problem but they have not given satisfaction as they permit liquids to escape.

More recently, the properties of a known product have been used for resolving this problem, the product being a semi-permeable membrane of a material inert to numerous chemical constituents and the structure of which is such that it is permeable to gas whilst completely retaining liquids.

This membrane has been used upto now in stoppers for containers which comprise a hole arranged in a plane perpendicular to the axis ofthe stopper, the membrane being fixed in a fluid tight manner whilst closing the hole.

Thus, the gases contained in the interior of the container may escape from the latter into the atmosphere without the liquid being able to flow to the outside. Nevertheless, the devices have not yet given satisfaction in the sense that the membrane is either exposed to shocks outside the container which are capable of damaging it and consequently then permitting the liquid to flow to the outside, or are recessed with respect to the outer surface of the stopper or of the container, but in this case a drop of the liquid present in the container can remain on the lower horizontal flat portion of the membrane whilst, in that case also, the membrane forms a depression in which water, such as rain water, may be trapped, the said water closing the pores of the membrane and depriving it of its properties of permeability to gases.

The aim of the invention is to overcome these disadvantages by producing a stopper of the type referred to in which the membrane permeable to the gases and impermeable to liquid is protected from external shocks as well as from any attack by rain water or other liquid arriving from the inside or from the outside.

To this end, the invention provides a stopper for closing a container, comprising an opening therethrough, means in the opening defining a tortuous fluid passage through the stopper, and a membrane permeable to gas but impermeable to liquid closing the passage at a position intermediate inner and outer ends thereof, the membrane being so arranged that it is not directly accessible through the outer end of said passage and in a normal orientation of the stopper liquid will drain naturally from the membrane surfaces.

In a preferred embodiment the said means defining the passage comprises an element inserted in the stopper opening and having an outer shape complementary to that of the opening.

The element can be formed of two substantially identical parts each of semi-cylindrical cross-section and closed at one end, their flat side walls being placed face to face with the membrane clamped between them, and the closed ends of the two parts facing in opposite directions.

Other preferred features of the invention will become apparent from the following description which is given with reference to the accompanying drawings; Figure 1 is a view in axial section of a stopper according to a preferred embodiment of the invention; Figure 2 is a sectional view on the line ll-ll in Figure 1; Figure 3 is a perspective view of the element detachably arranged in the axial passage of the stopper before the membrane is in place.

With reference to the drawing, Figures 1 and 2 show a stopper 1 comprising, in the usual manner, a cylindrical body 2 comprising an outer screw thread 3, a radial collar 4 on the upper part of its periphery and an annular fluid-tight packing 5 arranged beneath the said collar between the latter and the screw thread 3.

The stopper 1 comprises an annular skirt 6 provided in the normal manner so as to confer a sufficient rigidity on the stopper and it also comprises an axial cylindrical passage bounded by a cylindrical wall 7 co-axial with the skirt 6 and integral with the body 2 of the stopper.

An inserted element designated in its entirety by the reference 8 (Figure 3) is arranged in the axial passage 7. This inserted element is formed by two semi-cylindrical parts 9A, 9B each closed respectively, on the one hand, at one end by a wall 1 or, lOB and on the other hand along their diameter by a wall 11A, 11 B which extends between two diametrically opposed generatrices and each pierced by a substantially central hole 12A, 12B. These two parts 9A, 9B are arranged face to face in an inverse sense, that is to say in such a manner that the closed end of the part 9A is arranged opposite to the closed end lOB of the part 9B.

A membrane 13 of the known type available commercially is arranged between the two parts 9A, 9B and has the property of being permeable to gases whilst being completely impermeable with respect to liquids and inert with respect to numerous chemical products.

In advantageous manner, the walls 11A, 11 B each comprising around their central opening, complementary retension means which may be constituted for example by a circular groove i4 and a circular rib 15 adapted to coincide and clamp the membrane 13 between them.

In a manner which is also advaneageous, each part of the inserted element 8 comprises a projecting rib around its periphery which is adapted to cooperate with a groove provide in the inner surface of the wall 7 of the axial passage. Instead of such a "snap" system as indicated, a narow flange 16 on the element 8may be welded to the lower portion 17 of the part 7 of the element.

In considering Figure 1 it will be seen that the two parts 9A, 9B of the inserted element 8 arranged in opposite senses, define a sinuous path indicated by the arrows in Figure 1 comprising an intermediate portion formed by their central openings 12A, 12B which are closed by the membrane 13 which is arranged parallel to the wall of the axial passage 7, facing each of the semi-cylindrical walls of the two parts of the element 8, the sinuous passage leading, on the one hand, to the outside of the container and on the other hand, to the inside thereof and the wall of the element 8 preventing any direct axis to the membrane 13 from the outside or from the inside of the container.

Likewise it will be seen that, in the case where the container is inclined or inverted, and its liquid content wets the membrane 13, this liquid can drain away immediately when the container is returned to its initial position thus providing the membrane with its permeability to gases.

Moreover, if it happens that splashes of water or of some other liquid penetrate in to that portion of the sinuous path leading towards the outside, this liquid is accumulated againstthe lower wall 1 OA and may flow towards the outside if the container is suitably inclined.

It is understood that the membrane permeable to gases is thus completely protected from any mechanical damage and can be drained if it has been wetted thus always preserving its properties.

According to the Example shown in Figure 3, the inserted element 8 is produced by moulding in plastics material, the two parts 9A, 9B being produced from material by moulding and attached by a relativelythin portion of material forming a hinge and permitting the two parts of the element 8 to be closed whilst clamping the membrane 13 between them.

In an advantageous manner, the inserted element 8 may likewise be either force fitted or welded to the wall 7 of the axial passage in the stopper.

Claims (11)

1. A stopper for closing a container, comprising an opening therethrough, means in the opening defining a tortuous fluid passage through the stopper, and a membrane permeable to gas but impermeable to liquid closing the passage at a position intermediate inner and outer ends thereof, the membrane being so arranged that it is not directly accessible through the outer end of said passage and in a normal orientation of the stopper liquid will drain naturally from the membrane surfaces.

2. A stopper according to claim 1, wherein said passage includes a hole through a wall member generally parallel to the stopper axis, and the membrane is disposed adjacent said wall member and protected thereby against direct accesss through the outer end of the passage.

3. A stopper according to claim 1 or2,wherein s2id means comprise an element inserted in the said opening and having an eternal shape complementary to that of the said opening.

4. A stopper according to claim 3, wherein said element is formed of two parts having the same general shape and disposed with corresponding side surfaces and corresponding ends directed oppositely.

5. A stopper according to claim 4, wherein the said parts are moulded from plastics material and are hinged to one another.

6. A stopper according to claims 4 or 5 wherein said side surfaces are provided by walls, therebeing an opening through the walls forming a portion of said tortuous passage, and the walls clamping the said membrane between them.

7. A stopper according to claims 4, 5 or 6 wherein each part is semi-cylindrical in cross section and closed by an end wall at one of its ends.

8. A stopper according to claims 6 or 7, the parts comprise complementary locating means on the said facing walls for fixing the membrane in position.

9. A stopper according to any one of claims 3 to 8 wherein the said element comprises locating means adapted to co-operate with complementary means provided in the wall of the said stopper opening.

10. A stopper according to claim 9, wherein the said element is a force fit andlorwelded in the said opening.

11. A stopper substantially as herein described with reference to the accompanying drawings.