Abstract:
A drinking vessel comprises a generally cylindrical container ( 10 ) for containing liquid, and a lid ( 20 ). The lid comprises a generally cylindrical inner member ( 21 ) and a generally cylindrical sealing element ( 30 ) which surrounds the inner member ( 21 ). The container  10  further comprises a rim ( 14 ) and an inner circumferential sealing surface ( 15 ). The lid ( 20 ) is fixedly insertable into the container  10  in order, when the lid ( 20 ) is inserted, to cause the sealing element ( 30 ) to lie against the sealing surface so as normally to form a seal with the sealing surface ( 15 ). The seal is deformable by suction at the rim ( 14 ) such that under the action of the suction liquid within the container ( 10 ) is caused to flow from a chamber ( 13 ) inside the container out past the rim ( 14 ).

Description:
FIELD OF THE INVENTION 
     This invention relates to a drinking vessel of the type that, for example, comprises a generally cylindrical seal that lies against a generally cylindrical sealing surface in order to enable a user to draw liquid from a rim of the drinking vessel. 
     BACKGROUND OF THE INVENTION 
     Trainer cups that comprise a container for liquid and a lid including a mouthpiece, usually in the form of a spout, are well known for use at an intermediate stage in a child&#39;s development as the child moves from drinking from a feeding bottle or the breast to drinking from a conventional cup or glass. 
     However, at that stage, the child will not have learned that if cups are knocked over or shaken, the liquid inside will be spilt. Accordingly, there is a need for the development of trainer cups which are adapted not to spill their contents when shaken or upturned. 
     United Kingdom Patent Specification GB-A-2 266 045 describes such a cup in which a one-way valve is provided within the spout of the lid of a trainer cup. The valve is formed by a slit formed in an externally convex portion of a sheet of flexible material such as latex or silicone rubber. The valve opens in response to suction on the spout by the child, thereby allowing egress of fluid from the cup. The convexity of the valve provides the one-way characteristic of the valve. A second one-way valve is provided to allow ingress of air into the cup to prevent the build-up of a vacuum. 
     However, at some stage in a child&#39;s development, it will need to learn the skills involved in drinking from the rim of an ordinary cup as opposed to the intermediate type of vessel having a spout. Typically, this is done by wholly removing the lid from the trainer cup to prevent use of the spout. However, in doing so, the spill-resistance advantages are completely lost. The object of the present invention is to provide an improved drinking vessel which can be used as a trainer cup without employing a spout. 
     As well as being used by children, non-spill and shock resistant drinking vessels can be found useful by a range of other users. For example, the elderly, infirm, the disabled, and those returning from injury would also require such a drinking vessel, as there is an increased chance that the drinking vessel will be dropped on the floor or knocked over. A runner would also require a shock resistant drinking vessel, which would need to be designed to withstand shocks of a different nature to those of other end users. For example, the shock to a drinking vessel when it is dropped affects the fluids dynamics inside the vessel differently than if the vessel is subjected to repeated movements when being held by a runner. As such, a drinking vessel may be required to exhibit different and/or additional shock resistance characteristics depending on the nature of the end use of the drinking vessel. 
     United Kingdom patent specification no. GB-B-2 401 857 relates to an alternative cup that comprises a cylindrical container and a lid, the lid having a cylindrical outer element that provides a sealing surface, an annular seal and an inner element that serves to trap the seal between an inner surface of the outer element and an outer surface of the inner element. The annular seal and the sealing surface therefore form an annular valve. In use, a user sucks from the rim of the lid, causing a portion of the annular seal of the valve to rise from the sealing surface, thereby allowing liquid contained within the container to flow through the lid to the mouth of the user trying to drink from the cup via the opened portion of the valve. However, the alternative cup of this type employing the annular valve in the lid does not provide an optimum seal to prevent egress of liquid from the container, particularly when the cup is exposed to so-called “shock” movements, for example when the cup is suddenly shaken. Furthermore, it is also desirable to reduce the number of piece parts used to make the cup. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, there is provided a drinking vessel comprising a generally cylindrical container for containing liquid and a lid, the lid comprising a generally cylindrical inner member and a generally cylindrical sealing element surrounding the inner member, wherein the container further comprises a rim and an inner circumferential sealing surface, the lid being fixedly insertable into the container in order, when the lid is inserted, to cause the sealing element to lie against the sealing surface so as normally to form a seal with the sealing surface, the seal being deformable by suction at the rim such that under the action of the suction liquid within the container is caused to flow from a chamber inside the container out past the rim. 
     According to a second aspect of the invention, there is provided a drinking vessel comprising a generally cylindrical container for containing liquid, a generally cylindrical lid arranged to close the container, the lid comprising a generally cylindrical outer member having a rim and an inner circumferential sealing surface, a generally cylindrical inner member, a generally cylindrical sealing element surrounding the inner member and insertable within the outer member so as to bring the sealing element into abutment with the sealing surface, wherein the sealing element lies against the sealing surface so as normally to form a seal with the sealing surface, the seal being deformable by suction at the rim such that under the action of the suction liquid within the container is caused to flow from the chamber inside the container out past the rim. 
     So that liquid may efficiently pass through the seal when suction has been applied to the rim, the sealing member and the sealing surface may cooperate to define a plurality of circumferential channels. The plurality of channels may extend from the rim towards the base of the container, for example downwardly, and/or extend substantially in parallel from the end of the seal adjacent the rim down to or at a point near the base of the seal. The channels could extend in respective axes substantially parallel with a central axis of the seal and, when assembled, a longitudinal axis of the vessel. The channels could be capillaries or alternatively be formed from grooves in the outer surface of the sealing element. 
     The channels may contain a kink therein. This feature is provided in order to mitigate leakage from the seal formed between the sealing element and the sealing surface in the event of a so-called “shock condition” when the drinking vessel is shaken, possibly violently. This kink is provided in both the sealing element and the inner surface of the container or outer member (if present) in order to contribute to a labyrinthine path for liquid to follow to exit the vessel. Consequently, the inner surface of the container or outer member would mirror or follow this formation of the sealing element so as to provide a circumferential shoulder as part of the sealing surface. Where channels are provided, the portions of the sealing element and the sealing surface supporting the channels are in abutment when the drinking vessel is not being used. 
     These labyrinthine channels in certain instances will be spaced between about 0.4 mm to about 6 mm apart, but this range should not be understood as limiting. Spacing is configured dependent on drink flow rate requirements to suit the target user. If a higher drinking flow rate is required, closer labyrinthine channel spacing can be used to ensure a greater number of channels fit inside the user&#39;s lips when applied to the seal. The labyrinthine channels up the side of the seal may have a nominal cross sectional area typically between about 0.8 mm 2  and about 3.5 mm 2 , and a total length typically from about 5 mm to about 30 mm, depending upon application of the drinking vessel. This length range can include changes in direction of the labyrinthine path of the channels. It should be understood that the length and cross section of each labyrinthine channel is configured to possess suitable dimensions so that fluid striking an “entrance” of a labyrinthine channel is restricted and damped in its flow along the channel so that there is not enough inertia in the liquid to lift the seal at the end of the labyrinthine channel near the rim. The damping and restriction on the fluid is achieved due to boundary layer and turbulent flow effects on the fluid as it passes though the labyrinthine channels, which are configured to a suitable size based upon the required sealing performance of the drinking vessel, for example an adult runner would require higher seal shock load performance than a drinking vessel only tailored to resist spilling when knocked over, such as on a desk. 
     The proportions of the labyrinthine channel configuration can be tailored to generate higher flow but reduced sealing range and vice versa. The labyrinth system can be reduced in cross sectional area and increased in length to improve shock loading performance, but this also reduces drinking flow rate for the user of the drinking vessel. 
     The channels may deviate from a linear path and be generally V- or chevron shaped, or alternatively, the channels may zigzag between the upper and lower edges of the sealing element. By deviating the path of the channels, their overall length will increase relative to a linear channel, thus increasing the shock loading performance. 
     An inlet may be disposed in the sealing element at the entrance to the channels, with the inlet being in fluid communication with two or more channels, so that the liquid may enter the two or more channels through a common inlet. By reducing the total number of inlets, or in effect increasing the number of channels per inlet, the fluid resistance and therefore the shock loading performance of the vessel will be increased. The performance improvement will in part be due to the enlarged volume into which the fluid can flow, the increase in space available to the liquid being, in this example, as the inlet splits into two or more channels. 
     Different types of shock, for example shock caused by the swinging of a vessel as opposed to dropping it, affects the liquid in the vessel differently. Increasing the number of channels per inlet or increasing the length of the channels by introducing a kink or change of direction, will affect the liquid dynamics depending on the shock applied thereto. Therefore, these strategies of providing non-linear channels and multiple channels per inlet may be combined, or these strategies may be provided separately in different drinking vessels, depending on the performance required. 
     Hence, it can be seen that the sealing element cooperates with the sealing surface in order to provide a plurality of labyrinthine or non-straight channels or paths as a nexus between an internal volume of a drinking vessel and a rim of the drinking vessel. 
     According to the first aspect of the invention, the container may carry an internal thread at an upper end thereof below the rim, with the inner member having a counterpart external thread for engaging the container using the internal thread of the container. In order to prevent over-insertion and therefore application of excessive force on the sealing surface by the sealing element, a stop may be provided at a suitable position along the internal thread. It should nevertheless be appreciated that other techniques can be employed in order to maintain the lid in the container, for example a releasable snap fit. 
     It should also be appreciated that although the container according to the second aspect of the invention does not comprise a lid that screws into the container, such a lid can be provided based upon the above described principle. In this respect, the lid further comprises an outer member into which the above-mentioned inner member and sealing element screws. In such an example, the vessel carries an outer thread below a rim of the container for engagement with a counterpart inwardly-facing thread carried by the outer member. The outer member comprises a rim and an internal surface constituting a sealing surface. In order to prevent over-insertion and therefore application of excessive force on the sealing surface by the cylindrical seal, a stop may also be provided at a suitable position along the internal thread. Of course, as mentioned above, other techniques can be employed in order to maintain the lid in the outer member, for example a releasable snap fit. 
     In relation to the above embodiments, in order to facilitate the insertion of the inner member into the vessel or the outer member (depending upon implementation), the inner member further includes a grip that extends diametrically across the inner member. 
     In order to relieve pressure build-up in the vessel, the sealing element may include one or more air valves which equalise the pressure in the vessel after liquid has been withdrawn therefrom following or during a sucking action with respect to the seal. The air valves control the level of vacuum inside the cup. To increase cup sealing performance, the internal vacuum can be increased, which increases cup sealing performance as the outer edge seal at the rim is sucked closed by the internal vacuum. 
     Although, in the above examples, reference is made to a cylindrical sealing element that can be formed as a single piece part, for example an elastomeric seal formed over a polypropylene inner member, the sealing element can be an annular seal that can be, for example, removably pulled over the inner member. The sealing element is deformable so that it can move away from the sealing surface under suction to permit egress of fluid, but also so that the sealing element returns to its original position forming a seal. 
     Regarding the second aspect of the present invention, the outer member may be releasably detachable from the container. This may be done by way of cooperating screw threads on the outer element and container, by way of a releasable snap fit attachment mechanism, or any other suitable alternative. One advantage of the second aspect of the present invention is that the lid may be removed to refill the container without the sealing element being removed from against the sealing surface. 
     It is thus possible to provide a drinking vessel that has a better seal than provided by other non-spill drinking vessels where the user drinks from the rim of the cup. In this respect, egress of liquid from the cup is reduced further under shock force conditions. Furthermore, the drinking vessel can be constructed from fewer parts, and so is easier for a user to assemble, and fewer parts need to be cleaned, thereby improving manual cleaning time. Additionally, the need for fewer parts reduces manufacturing burden in respect of the vessel, which has both environmental and financial benefits. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       At least one embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is an exploded view of a drinking vessel constituting a first embodiment of the present invention; 
         FIG. 2  is an isometric view of a drinking vessel of  FIG. 1 ; 
         FIG. 3  is a schematic diagram in plan view of the drinking vessel of  FIG. 1 ; 
         FIG. 4  is a side view of the drinking vessel of  FIG. 1 ; 
         FIG. 5  is a cross-sectional view of the drinking vessel of  FIG. 4  along the line A-A; 
         FIG. 6  is another side view of the drinking vessel of  FIG. 1 ; 
         FIG. 7  is a cross-sectional view of the drinking vessel of  FIG. 6  along the line B-B; 
         FIG. 8  is a cross-sectional view of the drinking vessel of  FIG. 7  along the line D-D; 
         FIG. 9  is a cross-sectional view of the drinking vessel of  FIG. 7  along the line E-E; 
         FIG. 10  is a further side view of the drinking vessel of  FIG. 1 ; 
         FIG. 11  is a cross-sectional view of the drinking vessel of  FIG. 10  along the line C-C; 
         FIG. 12  is a schematic diagram of a pressure relief valve; 
         FIG. 13  is a schematic diagram of the pressure relief valve of  FIG. 12  in greater detail; 
         FIG. 14  is an exploded view of a drinking vessel constituting a second embodiment of the present invention; 
         FIG. 15  is a side view of the elastomeric seal of the second embodiment; 
         FIG. 16  is a perspective view of the elastomeric seal of the second embodiment from below said seal; 
         FIG. 17  is a perspective view of the elastomeric seal of the second embodiment from above said seal; 
         FIG. 18  is a close up of the channels of the elastomeric seal of the second embodiment; 
         FIG. 19  is a cross-sectional view of a drinking vessel including the elastomeric seal of the second embodiment; 
         FIG. 20  is an exploded view of a drinking vessel constituting a third embodiment of the present invention; and 
         FIG. 21  is a cross-sectional view of the third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Throughout the following description, identical reference numerals will be used to identify like parts. 
     With reference to  FIGS. 1 to 14 , and in particular  FIGS. 1 and 5 , a first embodiment of drinking vessel is shown comprising a container, generally indicated  10 , and a lid generally indicated  20 . The container  10  comprises a base  11  and an upstanding circumferential side wall  12 , defining therein a chamber  13  in which liquid is held during use. An upper edge of the side wall  12  defines a rim  14  from which a user drinks. Disposed within the container is an internal screw thread  16 , and positioned above the internal screw thread  16  is a circumferential shoulder  17 . Both the internal screw thread  16  and the circumferential shoulder  17  are adapted to engage with the lid  20 . An inner sealing surface  15  is defined on the inside of the chamber  13  between an upper edge of the rim  14  and the circumferential shoulder  17 . 
     The lid  20  is releasably attachable to the container  10  and comprises an inner member, generally indicated  21 , a sealing element, generally indicated  30 , and optionally a cap, generally indicated  40 . The inner member  21  comprises a cylindrical inner portion  22  and a coaxial outer portion  23 . The outer portion  23  is connected to the inner portion  22  by a series of radial extensions  24 , which define a series of apertures  25  therebetween through which liquid can pass. The outer portion  23  has an outer surface that includes an external screw thread  26  arranged to cooperate with the internal screw thread  16  of the container  10 , and also an outwardly extending lip  29  disposed above the screw thread  26  which abuts the circumferential shoulder  17  of the container  10  when the lid  20  is attached. The circumferential shoulder  17  acts as a stop which engages with the lip  29  to prevent the lid  20  from being screwed too far into the container  10 . Within the cylindrical inner portion  22  is a diametrically disposed upstanding grip  27  which is provided so that the inner member  21  can easily be manually screwed into the container  10 . Disposed around the upper edge of the cylindrical inner portion  22  is a first flange  28  which abuts the sealing element  30  to ensure a tight engagement therewith. 
     The sealing element  30  is made from an elastomeric material and comprises an annular body section  31  having a second flange  32  extending from the upper edge thereof. An annular shoulder  33  is provided at the inner surface of the body section  31 . When assembled, it is the shoulder  33  of the sealing element  30  that abuts the first flange  28  disposed around the upper edge of the cylindrical inner portion  22 . Further, the body section  31  has a base which abuts the radial extensions  24  between the inner portion  22  and the coaxial outer portion  23  of the inner member  21 . The body section  31  of the sealing element  30  creates a fluid-tight seal with the inner portion  22  of the inner member  21 . The second flange  32  on the sealing element  30  abuts the rim  14  of the container  10  and creates a fluid-tight seal therewith, the second flange  32  and the rim  14  combining to form a surface from which a user draws liquids during use. 
     Positioned around an inner surface of the body section  31  are a series of air valves, generally indicated  34 , which comprise notches  35  and outwardly extending flaps  36  ( FIGS. 7 and 11 ). The air valves  34  act to equalise pressure in the drinking vessel that accrues after liquid has been withdrawn from the chamber  13  during use. The air valves  34  control the level of vacuum inside the cup. At rest the flaps  36  abut the flange  28  and create a fluid-tight seal to prevent liquid from leaving the container  10  through the air valves  34 . The flaps  36  are deformable away from the flange  28  to allow air to enter the container  10  when the air pressure inside the chamber  13  is less than the air pressure on the outside of the chamber  13 , and air then enters to equalise the pressure. 
     Referring to  FIGS. 1 and 8 , disposed around and extending the length of the outer surface of the body section  31  of the sealing element  30  are a series of parallel projections  37 , defining therebetween a series of channels  38 . The channels  38  are in fluid communication with the apertures  25  between the radial extensions  24  on the inner member  21  of the lid  20 , and also between the lip  14  and the second flange  32 . The channels  38  can be spaced apart between 0.4 mm and 6 mm and between 5 mm and 30 mm long, depending on the required application. The channels  38  form part of a labyrinthine flow system, discussed below, to prevent unintentional egress of liquid from the container  10  when it is subjected to shock conditions such as being shaken. 
     The cap  40  is generally circular and comprises a cap rim  41 , a recessed central portion  42  and an opening flap  43 . The recessed central portion  42  locates over the inner portion  22  of the inner member  21 , and the cap rim  41  surrounds the rim  14  of the container and the second flange  32  of the sealing element  30  to close the drinking vessel and to prevent completely any liquid therein from leaking. The opening flap  43  is disposed at the periphery of the rim  41  and provides a user with a suitable surface to remove the cap  40 . It is intended that the cap  40  be attached to the container  10  when not in use, and it can easily be removed when the drinking vessel is used. 
     The drinking vessel further comprises a removable grip  44 , comprising an annular joining section  45  that engages with the side wall  12  of the container  10 , and two handles  46  projecting therefrom. The grip  44  can be attached to the container  10 , by inserting the base  13  of the container  10  into the joining section  45  and then sliding the joining section  45  up over the side wall  12  of the container. As shown in  FIG. 1  in particular, the circumference of the side wall  12  increases from the base  13  towards the rim  14  of the container  10 . The joining section  45  engages with the side wall  12  once the circumference of the joining section  45  equals that of the side wall  12  to form a snug fit. 
     As is more clearly shown in  FIG. 11 , the second flange  32  is manufactured to form as tight a seal as possible with the rim  14 . The angle of the second flange  32  when the sealing element  30  is not assembled is nearer to a horizontal plane than when the sealing element  30  is engaged with the inner portion  22 , so that when assembled the second flange  32  is pulled down onto the rim  14  to produce a firm seal. 
     As is more clearly shown in  FIG. 13 , there are two distinct fluid flow systems, one for liquid and one for air, which enable optimum functional characteristics. A liquid flow system extends from the chamber  13  and incorporates the apertures  25  between the radial extensions  24 , and the channels  38  provided between the parallel projections  37  and the inner sealing surface  15 . As shown in  FIG. 13 , the liquid flow system is kinked between the channels  38  and the apertures  25 . This kink is provided in order to mitigate leakage from the seal formed between the sealing element  30  and the sealing surface  15  in the event of a so-called “shock condition” when the drinking vessel is shaken, possibly violently. This kink contributes to a labyrinthine flow system for liquid to follow to exit the vessel. The liquid flow system then extends between the rim  14  and the flange  32 . An air flow system extends through the air valves  34  and the apertures  25  between the radial extensions  24 . The air and the liquid flow systems exist so that as liquid is drawn from the chamber  13 , air can enter the chamber  13  to equalise the pressure created by the egress of liquid. 
     In use, the lid  20  is releasable from the container  10  by unscrewing the inner member  21  from the container  10 . The chamber  13  in the container  10  can then be filled with liquid, and the lid  20  can then be reattached by screwing the inner member  21  back into the container  10 . To drink from the drinking vessel, a user lifts the container to their lips, and attempts to draw liquid from the chamber  13  by sucking from the rim  14  and the sealing element  30 . The sucking action creates a pressure differential between the inside of the chamber  13  and the mouth of the user, thereby causing liquid to be drawn from the chamber  13  and out past the rim  14  and into the mouth of the user. The liquid flows through the liquid flow system, i.e. from the chamber  13 , and past the apertures  25  in between the outer portion  23  and the cylindrical inner portion  22  of the inner member  21 . The liquid then then flows into the channels  38  between the parallel projections  37  on the outer surface of the sealing element  30  in the region where the mouth of the user engages the rim  14 . The liquid then exits the vessel between the flange  32  of the sealing element  30  and the rim  14  of the container  10 . 
     So that the air pressure inside the chamber is equalised, air is then drawn back inside the chamber  13  through the air valve  34 , as a result of a negative pressure formed in the chamber  13  when the liquid exited the chamber  13 , causing the outwardly extending flaps  36  to flex away from the first flange  28 . Once the air is equalised, the flaps  36  return to the rest position abutting the first flange  28  on the inner portion  22  to prevent any leakage of liquid therethrough. 
     Referring to  FIGS. 14 to 19 , there is shown an alternative embodiment of sealing element  50  in use with a container  10  and inner member  21  as previously described. 
     The sealing element  50  is made from an elastomeric material and comprises an annular body section  51  having a second flange  52  extending from an upper edge thereof. An annular shoulder  53  is provided at the inner surface of the body section  51 . Equivalently to the first embodiment of sealing member  30 , when assembled, it is the shoulder  53  of the sealing element  50  that abuts the first flange  28  disposed around the upper edge of the cylindrical inner portion  22 . Further, the body section  51  has a base which abuts the radial extensions  24  between the inner portion  22  and the coaxial outer portion  23  of the inner member  21 . The body section  51  of the sealing element  50  creates a fluid-tight seal with the inner portion  22  of the inner member  21 . The second flange  52  on the sealing element  50  abuts the rim  14  of the container  10  and creates a fluid-tight seal therewith, the second flange  52  and the rim  14  combining to form a surface from which a user draws liquid during use. 
     As most clearly shown in  FIG. 17 , positioned around an inner surface of the body section  201  are a series of air valves, generally indicated  54 , which comprise notches  55  and outwardly extending flaps  56  ( FIG. 19 ). As previously described, the air valves  54  act to equalise pressure in the drinking vessel that accrues after liquid has been withdrawn from the chamber  13  during use. The flaps  56  are deformable away from the flange  28  to allow air to enter the container  10  when the air pressure inside the chamber  13  is less than the air pressure on the outside of the chamber  13 , and air then enters to equalise the pressure. 
     Referring to  FIGS. 14 to 18 , disposed around and extending the length of the outer surface of the body section  51  of the sealing element  50  are a series of parallel projections  57 , defining therebetween a series of channels  58 . The channels  58  are in fluid communication with the apertures  25  between the radial extensions  24  on the inner member  21  of the lid  20 , and also between the lip  14  and the second flange  52 . The channels  58  can be spaced apart between 0.4 mm and 6 mm and between 5 mm and 30 mm long, depending on the required application. The channels  58  in this embodiment of sealing element  50  are generally V- or chevron shaped in order to extend their length relative to the linear channels  38  as shown in the first embodiment of sealing element  30 . The increased length of the channels  58  increases the resistance and damping of liquid in the channels  58 , and as such further helps to mitigate leakage from the drinking vessel during shock conditions. 
     As shown most clearly in  FIG. 17 , the channels  58  include inlets  59  disposed at the lower edge of the sealing element  50 . Each inlet  59  includes a bifurcation  60 , making the inlet  59  generally T-shaped. As a result of the bifurcation  60 , each inlet  59  supplies two channels  58 , which extend one from each branch of the bifurcation  60 . By having one inlet  59  per two channels  58  further increases the resistance and damping of the liquid, thus also mitigating the leakage of liquid from the drinking vessel during shock conditions. Although not shown here, one inlet  59  could be in fluid communication with three, four or even more channels  58  to further increase the liquid resistance, should this be required for particular uses of drinking vessel. For example, cups to be used by runners may benefit from increased liquid resistance because the cup will be subject to greater and more frequent shocks than a drinking vessel that will be used in the home or at work. Therefore, depending on use, a balance can be achieved between the ease of drawing liquid from the vessel against the need to increase shock performance. 
     As more clearly shown in  FIGS. 20 and 21 , according to a second aspect of the present invention there is shown an alternative drinking vessel, comprising a container  70 , and a lid, generally indicated  75 . The container  70  comprises a base  71  and an upstanding circumferential side wall  72 , defining therein a chamber  73  in which liquid is held during use. An upper edge of the side wall  72  defines an external screw thread  74  to which the lid  75  can be releasably attached in order to fill the vessel with liquid. 
     The lid  75  comprises an inner member, generally indicated  80 , a sealing element, generally indicated  90 , and an outer member, generally indicated  100 . 
     The inner member  80  comprises an upper annular portion  81  and a lower annular portion  82 , with a groove  83  therebetween. The upper annular portion  81  includes an overhang which cooperates with the sealing element  90  when combined. The outer member  100  comprises a cylindrical inner portion  101  and a coaxial outer portion  102 . The outer portion  102  is connected to the inner portion  101  by a series of radial extensions  103 , which define a series of apertures  104  therebetween through which liquid can pass. The outer portion  102  has a collar  108  including an internal screw thread  105  arranged to cooperate with the external screw thread  74  of the container  70 , and also an outwardly extending rim  106  disposed above the screw thread  105 . Within the cylindrical inner portion  101  is a series of flexible teeth  107  which permit a snap fit engagement with the inner member  80 , as more clearly shown in  FIG. 21 . 
     The sealing element  90  is made from an elastomeric material and comprises an annular body section  91  having an inner flange  92  and an outer flange  93 , with a groove therebetween in which overhang  85  fits when the lid  75  is assembled. When assembled, the inner flange  92  fits within the groove  83  of the inner member  80 . The body section  91  of the sealing element  90  creates a fluid-tight seal with the inner member  80 . The outer flange  93  on the sealing element  93  abuts the rim  106  of the outer member  100  and creates a fluid-tight seal therewith, the outer flange  93  and the rim  106  combining to form a surface from which a user draws liquids during use. The sealing element  90  has a series of channels  94 , which cooperate with the apertures  104  in the outer member  100  in an equivalent manner as described in relation to the first and embodiment, so this will not be repeated. However, the alternative channel arrangements described above could also apply to the sealing element  90  of this embodiment. 
     The entire lid  75  can be removed from the container  70  to fill the container  70  before use by unscrewing the cooperating screw threads  74 , 105  between said lid  75  and said container  70 .