GB2541711A

GB2541711A - Receptacle and closure system

Info

Publication number: GB2541711A
Application number: GB1515251.5A
Authority: GB
Inventors: Zanatta Omar; Richardson Joanne
Original assignee: Liquid Div Ltd
Current assignee: Liquid Div Ltd
Priority date: 2015-08-27
Filing date: 2015-08-27
Publication date: 2017-03-01
Also published as: WO2017032965A1; US20180229904A1; BR112018003924A2; ZA201801985B; EP3341301A1; CL2018000518A1; GB201515251D0; CN108137190A; AU2016310593A1

Abstract

A lid 6 with an external screw thread is suitable to close a cup 3 with a screw thread on its internal surface adjacent its rim. Alternative fasteners to screw threads could be used. The lid can have a vent in its upper wall selectively closable by a movable element such as a lever, a plug or a cap. A vent could alternatively be opened by a ring pull or breaking foil. The closure may be entirely covered by removable or breakable foil adhered to the rim of the cub above the closure. The screw threads may each be a broken helix. The closure can include a handle and a resilient seal. A stem 5 to support the cup could collapse into a sleeve 10 within the cups interior. An alternative cup has a sleeve extending inwards; a stem collapsible into the sleeve or extendable out from it; an elongate groove in the sleeve joined to transverse side grooves; and projections from the stem engaging with the grooves to secure the stem in extended and collapsed positions.

Description

Receptacle and Closure System

Field of the Invention

This invention relates to a receptacle, a receptacle system and closure system.

Background of the Invention

Drinks receptacles come in many different shapes, sizes and styles .

In terms of drinking wine, cocktails or champagne, the receptacle comprises a bowl standing on a stem above a base. The general term 'stemware' is sometimes used. This allows the beverage to be held without being warmed by the drinker's hands. The receptacle can be of any shape, although the term 'bowl' is used throughout and is intended to cover goblet, cocktail and flute shapes also The receptacle can be of any material, but is typically glass, crystal glass or plastics material.

In certain situations, for example on aircraft or trains, the motion of travel can cause the beverage to be knocked-over or spilled. In aircraft, in particular, turbulence is a common cause of drinks being spilled over passengers.

For stemmed glasses, such as wine or champagne glasses the higher centre of gravity can be a problem insofar as toppling of the glass is more likely.

It is possible to buy a drinks receptacle, typically in the form of a plastic wine glass, which has wine already in the bowl and sealed within the bowl by a foil wrap extending over the top of the the bowl. The receptacle Is purchased after which the foil lid is peeled off to access the wine. The receptacle is usually thrown away after use. Whilst such receptacles are suitable for non gaseous liquids, such as wine and water, they are not suitable for carrying gaseous drinks such as sparkling wine or Prosecco™.

Suimnary of the Invention A first aspect of the invention provides a liquid receptacle system comprising: a receptacle comprising a bowl having an upper opening surrounded by a rim, wherein a screw thread is provided on the interior surface of the bowl, substantially adjacent said rim; and a removable closure for sealing the bowl, the closure having a corresponding external screw thread which in use engages with the interior screw thread of the bowl to enclose contents within the bowl.

The closure may comprise a wall having upper and lower surfaces, and wherein a means of pressure-release is provided in or on the closure wall.

The pressure-release means may comprise an aperture passing through the closure wall, and a movable part accessible on or from the upper surface to enable a user, in use, to open the aperture .

The movable part may be further configured to be able to reseal the aperture after opening.

The pressure release means may be a pivotable flap or door located within or over the aperture and arranged to be moved by user force to open the aperture.

The movable part may be initially joined with the closure wall with a region or weakness around at least part of its perimeter to permit its disjoining due to user force.

The pressure-release means may be a plug that Is supported above the aperture and is movable up and down to open and close the aperture respectively.

The pressure-release means may be a stopper that fits over the aperture in a press-snap or threaded manner.

The pressure release means may comprise a ring-pull -type element provided within the closure wall, operation of which is effective to open an aperture.

The pressure release means may comprise a lever, button or switch exposed on the upper wall of the closure wall, and movable within a slot, effective to open and close an aperture located elsewhere In the closure wall.

The pressure release means may comprise an aperture within the closure wall which is sealed with a film or foil, breakable by user action. A lever or similar tool may be attached to the closure wall's upper surface, adjacent the aperture, and is movable to effect breaking of said film or foil.

The closure may be entirely covered by a removable or breakable film or foil.

The film or foil may be adhered or otherwise fixed to the rim of the receptacle, above the closure.

The system may further comprise reinforcing elements on, above or below the film or foil.

The screw threads of the system may be helical, either continuous or broken.

The system may further comprise a resilient pressure seal located around the interface between the receptacle and closure .

The closure may comprise a handle on its upper surface.

The receptacle bowl may be supported by a stem that is movable in relation to the bowl between first and second configurations .

The bowl may comprise a sleeve extending inwardly from the bowl's lower external surface within which the stem is connected and movable selectively between an extended configuration and a collapsed configuration. A second aspect of the invention provides a drinks receptacle apparatus, comprising: - a drinking glass or cup comprised of a bowl having an internal engagement portion substantially adjacent its upper rim on the internal bowl surface, the opposite, external bowl surface being smooth; and - a lid having a downwardly extending portion carrying an exterior engagement portion shaped and dimensioned to cooperate with the internal engagement portion of the glass or cup to provide a sealed cover, the lid further having a user-operable pressure release means. A third aspect of the invention provides a liquid receptacle comprising a bowl connected to a stem, wherein the stem is arranged to be movable relative to the bowl between extended and collapsed configurations, wherein the bowl comprises a sleeve extending inwards from the bowl's lower surface within which sleeve the stem is connected and movable selectively between the configurations, the Interior of the sleeve having a groove which comprises an elongate groove having opposite first and second ends, and transverse side grooves at, or in the region of, said first and second ends of the elongate groove providing respective locking positions, the stem comprising a protrusion on its outer surface which is located within the groove and which in use is movable from one of the side grooves into the elongate groove by relative rotation of the bowl to the stem, along the elongate groove, and into the other side groove by relative rotation.

Brief Description of the Drawings

The invention will now be described, by way of non-limiting example, to accompanying drawings, in which:

Figures 1(a)-1(d) are front and sectional views of a first embodiment drinking receptacle system In the form of a wine glass with telescopic stem arrangement and lid;

Figures 2(a)-2(e) are perspective views of a section of the Figure 1 wine glass;

Figure 3 is a perspective view of a second embodiment receptacle system in the form of a tumbler and lid;

Figures 4 (a) and 4 (b) are sectional and close-up views of the second embodiment receptacle system;

Figure 5 is a perspective view of the Figure 3 tumbler;

Figures 6(a) and 6(b) are upper and lower views of the Figure 3 tumbler lid;

Figures 7(a) and 7(b) are sectional and side views of an alternative lid that can be employed in either embodiment;

Figures 8(a)-8(d) are perspective, top, sectional and side views of an alternative lid that can be employed in either embodiment;

Figure 9 is a perspective view of an alternative lid that can be employed in either embodiment;

Figure 10 is a perspective view of an alternative lid that can be employed in either embodiment;

Figures 11(a)-11(c) are perspective views of alternative lids that can be employed in either embodiment;

Figures 12(a)-12(e) are perspective views of an alternative lid that can be employed in either embodiment;

Figure 13 shows perspective views of an alternative lid that can be employed in either embodiment;

Figures 14(a)-14(c) are perspective views of an alternative lid that can be employed in either embodiment;

Figures 15(a)-15(d) are perspective views of an alternative lid that can be employed in either embodiment;

Figures 16(a) and 16(b) are perspective views of an alternative lid that can be employed in either embodiment; Figure 17 is a perspective view of the Figure 3 system, employing also a sealing ring;

Figures 18 (a) and 18 (b) are side and perspective views of an alternative receptacle system, with broken threads;

Figures 19(a) and 19(b) are side and perspective views of an alternative receptacle system, with broken threads;

Figures 20(a) to 20(d) are perspective views showing a film or foil seal located over a lid;

Figures 21 (a) to 21 (c) are perspective views showing multi film or foil layer embodiments; and

Figures 22(a) to 22(f) are perspective views showing film or foil seal layers with reinforcement elements.

Detailed Description of Preferred Embodiments

Embodiments herein describe drinks receptacles having a closure lid to prevent the spillage of liquid held within the bowl of the receptacle. The lid is removable, and in some embodiments is secured to the receptacle by means of a helical screw thread arrangement, with the screw threads being respectively on an outer surface of the lid and the interior surface of the receptacle. This allows the lid to be gradually unscrewed by a user to reduce the chances of liquid being spilled and also to allow the gradual and controlled release of gas, e.g. in the case of carbonated or sparkling drinks. The fact that the engagement means, i.e. the screw threads, are internal to the bowl avoids contact with a user's mouth which might otherwise cause irritation or skin damage. The outer surface of the bowl can therefore be smooth. The closure systems described herein are also found to maintain pressure within the receptacle at altitude, e.g. to keep champagne or other carbonated beverages sparkling.

Referring to Figure 1(a), an item of stemware according to a first embodiment is provided in the form of a wine or champagne glass 1, although it can take any form and can be made of any material or combination thereof. For ease of explanation, the term 'wine glass' will be used throughout.

The wine glass 1 comprises a bowl 3 having an opening 4 at the top into which liquid can be poured and drunk from. From a distal end of the bowl 3 protrudes an elongate stem 5 which can be of any cross-sectional shape. A removable lid 6 is connected to the upper rim of the bowl 3 and closes the opening 4. At the distal end of the stem 5 is a base 7 which is horizontal relative to the stem and is used to support the wine glass 1 on a flat surface.

The stem 5 and bowl 3 may be formed from the same material or may be different materials. For example the bowl 3 may be made from plastic and the stem from aluminium.

The wine glass 1 shown in Figure 1 (a) is configured to be collapsible from the shown configuration into the configuration shown in Figure 1 (b) . This is by means of the stem 5 being arranged to telescopically locate within an inner sleeve that extends upwardly within the bowl 3. As shown in Figure 1 (b), this telescopic stem 5 arrangement allows the bowl 3 to be movable downwards towards the base 7 which lowers the centre of gravity and makes spillage, e.g. due to aircraft, train or car motion, less likely. It also permits easy storage. For the avoidance of doubt, note that the shape or capacity or integrity of the bowl 3 does not change.

Referring to Figure 1 (c), the profile of the bowl 3 includes an inner sleeve 9 that extends vertically upwards towards the opening 4. The sleeve 9 is hollow and its interior channel 10 is sealed from the bowl's interior so that no liquid can pass from the bowl into the channel.

The stem 5 and channel 10 are dimensioned such that the stem can move up and down in the manner of a piston-and-cylinder, thereby providing the extended and collapsed configurations of Figures 1 (a) and 1 (b) . The cross-sectional shape of the channel 10 and stem 5 are the same or similar to ensure a reasonably tight fit, and in this case are circular but can be of any shape. As Figure 1(b) shows, the lengths of the stem 5 and channel 10 are dimensioned so that the stem is almost entirely within the sleeve when collapsed. Figure 1 (d) shows the collapsed configuration in cross section with liquid present within the bowl 3.

Referring to Figures 2(a) to 2 (e), a locking system is arranged for selectively and temporarily locking the relative position of the stem 5 within the channel 10 in the extended and collapsed configurations. This system will now be described, although it will be appreciated that alternatives are possible. In overview, the outer surface of the stem 5 comprises an external protrusion, or slider 27, that locates within a U-shaped channel 21 provided in a sleeve internally located within the channel 10. The U-shaped channel 21 has an elongate vertical slot between two transverse locking slots 23, 25 at the top and bottom respectively. As will be seen in Figure 2(a) in the extended configuration the slider 27 locates within the top slot 23. Figure 2(b) shows the slider 27 located within the bottom slot 25, representing the collapsed configuration. Figures 2(c) to 2(e) show intermediate positions of the slider 27 as the user returns the glass 1 to the extended configuration.

The removable closure system, or lid system, will now be described in greater detail, with the above embodiment wine glass 1 being useful for context in relation to the lid 6. Also, Figure 3 shows an alternative form of drinking glass system 30, which also employs the same lid system 6 on a tumbler 40. The manner in which the lids 6 of each connect to either glass 1, 40 is the same.

Referring to Figures 3 and 4, the lid 6 comprises in this case a circular piece of material having an outer ring 31 with an external, circumferential lip 32 that in use locates over the rim 15, 39 (see also Figure 2(a)) of the glass 1, 40. A central section 33 extends from a sloping section 37 to complete the lid 6. A cross-shaped handle or grip 35 is provided over the central section 33, and enables easy rotation of the lid 6 relative to the glass 1, 40. The lid 6 can be formed of a single piece of plastics or other material, e.g. all sections formed integrally.

Figure 4 (b) shows a close-up section of the lid 6 as it locates over the rim 15, 39 of the glass 1, 40. The internal wall of the glass 1, 40 has, adjacent the rim 15, 39 a helical threaded portion 41 thereby leaving the opposite, external wall, smooth. The underside of the lid 6 has a downwardly extending collar 42 which defines between it and the lip 32 a gap closely corresponding to the wall thickness of the glass 1, 40. The outer, circumferential wall of the collar 42 carries a corresponding threaded portion 43 to enable, in use, the lid 6 to be screwed onto the glass 1, 40 to provide the connection shown in Figure 4(b) which is watertight.

In addition, the rim 15, 39 and the corresponding underside of the ring 31 are shaped so as to provide further sealing. In this example, the ring underside carries a protrusion 44 that locates within a correspondingly-positioned and shaped indentation.

Figure 5 shows the glass 40 with the lid 6 removed, to indicate the internal threaded portion 41. Figures 6(a) and 6 (b) show the lid 6 from the upper and lower sides, in which the various above-described features are shown, including the threaded portion 43. An indication of opening and closing direction is embossed or printed on the lid 6 upper surface.

As will be appreciated, the above-described lid 6 and the associated internal threading on the receptacle provides a closure system that avoids sharp or jagged edges on the exterior of the drinking surface and therefore avoids damage or irritation to the user. This is particularly important if the glass 1, 40 is used in a transport setting, such as on an aircraft or train, where movement is unpredictable. In addition, its combination with the first embodiment, collapsible glass, provides a compact and more stable product.

The threading also permits a gradual, user-controllable opening motion avoiding spillage and allowing gradual release of carbonating gas in such beverages.

Referring now to Figures 7(a) and 7(b) a further embodiment is shown, which is an alternative form of lid 50. It comprises a slightly different form of handle 51, but otherwise works along the same lines as the previous embodiment in that it has a downwardly projecting collar which carries a helical threaded portion 53 for screw-like connection to the interior threading of a glass 1, 40.

Figures 8 (a)-(d) show a still further embodiment lid 55, as another alternative. It comprises a plurality of blades 57, in this case eight, on the upper side which act as handles. Otherwise, it works along the same lines as the previous embodiment in that it has a downwardly projecting collar which carries a helical threaded portion 59 for screw-like connection to the interior threading of a glass 1, 40.

Figure 9 shows a further embodiment lid 60. It comprises a main section which connects to the glass 1, 40 in the same way as previous embodiments, using corresponding threaded portions 62. An outer ring part 61 is connected to a sloping wall 63 which extends to a lower, central portion 65. A handle 67 is provided by a separate member, bowl-like in shape, with a central handle blade. The handle 67 is supported on a plurality of posts 69 connected between its base wall and the top of the main section. The handle 67 may move up and down relative to the main section, as shown.

Figure 10 shows a further embodiment lid 70. It comprises a main section, substantially similar to that of Figure 9, which connects to the glass 1, 40 in the same way as previous embodiments, using corresponding threaded portions 71. A handle 73 is provided by an upstanding blade. At the end of the blade 73 is a separate opener section 75 which covers an aperture 77 which extends through the lid 70. The opener 75 is connected over the aperture 77 in such a way that user force in the direction shown breaks what is otherwise an airtight seal. In this way, carbonated gases, for example, can be released whilst the lid 70 remains screwed to the glass 1, 30.

Figures 11 (a)-(c) show a further embodiment lid 80, also suitable for releasing gas pressure as for the previous embodiment. In this case, the main section is largely the same, although a hatch 81 is provided within the main surface with at least a partially weakened perimeter to permit fracture and therefore opening. Figure 11(b) shows the lid 80 in which the user has pushed the hatch 81 down by exerting appropriate pressure. Figure 11(c) shows an alternative in which a hatch 82 is pivoted about its centre to release pressure .

Figures 12(a)-(e) show further embodiment lids 90, also suitable for releasing gas pressure as for the previous two embodiments. The main section is the same, but various different types of openings are employed which the user can operate to vent gas from the glass 1, 40 underneath. Figure 12(a) shows the lid 90 with a snap-close lid 91. Figures 12(b) and 12(c) shows the lid 90 with different screw-top lids 92, 93. Figure 12(d) shows the lid 90 with a flap-type opener 94 which carries a plurality of smaller stoppers which engage within corresponding holes in the main section. Figure 12(e) shows the lid 90 with a snap-top opener 95 which is hinged with respect to the main section.

Figures 13(a) and 13(b) show a further embodiment lid 100, also suitable for releasing gas pressure. The main section is the same as previous ones, although there is provided a mechanism in which a lever or switch 101 is provided at a different part of the lid 100 as a corresponding opening 102 which it controls. As shown, movement of the lever or switch 101 along a constrained path is effective to open and close the opening 102.

Figures 14(a)-14(c) show further embodiment lids 110, each employing a respective different form of mechanical stopper 111, 112, 113 to permit user opening and closing, e.g. for drinking or pressure release.

Figures 15(a)-15(d) show further embodiment lids 120, each employing a respective different form of ring-pull 121, 122, 123, 124 to permit user opening (in the manner of a conventional ring-pull on a can) for drinking or the release of pressure.

Figures 16(a) and 16(b) show further embodiment lids 130, in which an aperture is covered or filled with a pierce-able film or foil 131. In the case of Figure 16(a) the foil 131 can be broken by the user's finger or using a tool, e.g. an item of cutlery. In the case of Figure 16(b) a lever or similar tool 133 is provided adjacent the foil 131 to effect piercing. Piercing is provided to permit pressure release.

Figure 17 shows any one of the above-described lids when connected by the threading arrangement to the glass 40. In this case, one or more sealing rings 140 are provided around the interface between the lid and glass 40 to provide a pressure seal.

Figures 18(a) and 18(b) show any one of the above-described lids when connected by the threading arrangement to the glass 40. In the case of Figure 18(a) it will be seen that the threads 136 follow a helical path but are discontinuous, and employ a fillet seal to provide additional tightness. In the case of Figure 18 (b) the threads 137 are partial and spaced apart, to reduce aesthetic impact. Similarly, Figures 19(a) and 19(b) show any one of the above-described lids when connected by the threading arrangement to the glass 40. In the case of Figure 19(a) it will be seen that the threads 138 also follow a helical path but are discontinuous, and employ a fillet seal to provide additional tightness. In the case of Figure 19(b) the threads 139 are partial and spaced apart, to reduce aesthetic impact. There are a greater number of threads compared with the Figure 18(b) version.

In addition to the use of any one of the above-described lids, there can be provided a removable seal which is initially adhered to the rim, either above or below the lid. The seal can be formed of aluminium foil, or similar material.

For example. Figures 20(a)-20(d) show alternative arrangements whereby a foil or film layer 140 is adhered to the glass 1, 40, over any of the lids previously described. A tab 141 at one side permits a user to peel-off the layer 140, or alternatively, it can be peeled, to reveal the lid beneath, which can then be operated or opened as previously described. In this case, ring-pull type lids, are indicated.

Figures 21(a)-21(c) show alternative arrangements of a film or foil system in which there is at least an upper layer 160 of film or foil, and optionally, an internal layer 161, and the possibility of one or more stiffening elements 162 in-between.

In terms of stiffening elements. Figures 22 (a)-22(f) show different arrangement of such elements, which can be provided on top of, or below, either or both of the upper and/or internal film or foil layer(s) to maintain strength.

In overview, a drinks receptacle and associated closure system(s) have been described, which are found particularly useful for transport applications, e.g. on an aircraft, boat or train. The receptacle may be stemware or a tumbler or indeed it may be of any shape and side. It may comprise a collapsible stem, to aid storage and stability. The closure system is typically a removable lid or cap, having an external threading, arranged in use to mate with internal threading on the glass so that the surface is smooth. Further, pressure release means (both one-time-use, and re-usable) have been described in relation to the lid or cap, to further avoid spillage. Various types of sealing system have been described, and whilst a continuous thread on the lid is preferred, it can be partial or broken, and/or used in association with fillet seals to improve tightness. Additionally, a removable film or foil can be used to further improve sealing.

It will be appreciated that the above described embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present application.

Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and/or combination of such features.

Claims

1. A liquid receptacle system comprising: a receptacle comprising a bowl having an upper opening surrounded by a rim, wherein a screw thread is provided on the interior surface of the bowl, substantially adjacent said rim; and a removable closure for sealing the bowl, the closure having a corresponding external screw thread which in use engages with the interior screw thread of the bowl to enclose contents within the bowl.

2. A system according to claim 1, wherein the closure comprises a wall having upper and lower surfaces, and wherein a means of pressure-release is provided in or on the closure wall.

3. A system according to claim 2, wherein the pressure-release means comprises an aperture passing through the closure wall, and a movable part accessible on or from the upper surface to enable a user, in use, to open the aperture.

4. A system according to claim 3, wherein the movable part is further configured to be able to re-seal the aperture after opening.

5. A system according to claim 3 or claim 4, wherein the pressure release means is a pivotable flap or door located within or over the aperture and arranged to be moved by user force to open the aperture.

6. A system according to claim 5, wherein the movable part is initially joined with the closure wall with a region or weakness around at least part of its perimeter to permit its disjoining due to user force.

7. A system according to claim 3 or claim 4, wherein the pressure-release means is a plug that is supported above the aperture and is movable up and down to open and close the aperture respectively.

8. A system according to claim 3 or claim 4, wherein the pressure-release means is a stopper that fits over the aperture in a press-snap or threaded manner.

9. A system according to claim 2, wherein the pressure release means comprises a ring-pull -type element provided within the closure wall, operation of which is effective to open an aperture.

10. A system according to claim 2, wherein the pressure release means comprises a lever, button or switch exposed on the upper wall of the closure wall, and movable within a slot, effective to open and close an aperture located elsewhere in the closure wall.

11. A system according to claim 2, wherein the pressure release means comprises an aperture within the closure wall which is sealed with a film or foil, breakable by user action.

12. A system according to claim 11, wherein a lever or similar tool is attached to the closure wall's upper surface, adjacent the aperture, and Is movable to effect breaking of said film or foil.

13. A system according to any preceding claim, wherein the closure Is entirely covered by a removable or breakable film or foil.

14. A system according to claim 13, wherein the film or foil is adhered or otherwise fixed to the rim of the receptacle, above the closure.

15. A system according to claim 14, further comprising reinforcing elements on, above or below the film or foil.

16. A system according to any preceding claim, wherein the screw threads are helical.

17. A system according to claim 16, wherein one or both screw threads are broken, with gaps in between.

18. A system according to any preceding claim, further comprising a resilient pressure seal located around the interface between the receptacle and closure.

19. A system according to any preceding claim, wherein the closure comprises a handle on its upper surface.

20. A system according to any preceding claim, wherein the receptacle bowl is supported by a stem that is movable in relation to the bowl between first and second configurations.

21. A system according to claim 20, wherein the bowl comprises a sleeve extending inwardly from the bowl's lower external surface within which the stem is connected and movable selectively between an extended configuration and a collapsed configuration.

22. A closure arranged for use in the liquid receptacle system according to any preceding claim.

23. A drinks receptacle arranged for use in the liquid receptacle system according to any preceding claim.

24. A drinks receptacle apparatus, comprising: - a drinking glass or cup comprised of a bowl having an internal engagement portion substantially adjacent its upper rim on the internal bowl surface, the opposite, external bowl surface being smooth; and - a lid having a downwardly extending portion carrying an exterior engagement portion shaped and dimensioned to cooperate with the internal engagement portion of the glass or cup to provide a sealed cover, the lid further having a user-operable pressure release means.

25. A liquid receptacle comprising a bowl connected to a stem, wherein the stem is arranged to be movable relative to the bowl between extended and collapsed configurations, wherein the bowl comprises a sleeve extending Inwards from the bowl's lower surface within which sleeve the stem is connected and movable selectively between the configurations, the interior of the sleeve having a groove which comprises an elongate groove having opposite first and second ends, and transverse side grooves at, or in the region of, said first and second ends of the elongate groove providing respective locking positions, the stem comprising a protrusion on its outer surface which is located within the groove and which in use is movable from one of the side grooves into the elongate groove by relative rotation of the bowl to the stem, along the elongate groove, and Into the other side groove by relative rotation.