FIELD AND BACKGROUND OF THE INVENTION

The invention relates to an anti-spill cup according to the introductory portion of claim 1 and to a valve assembly for use in such an anti- spill cup. Such an anti-spill cup is known from international patent application WO 93/19718. In general, anti-spill cups are provided with a lid which forms a sealing at the topside of the cup, while a drinking passage extends through the lid. As the lid seals off the cup, the risk of spilling is considerably reduced while the drinking passage allows drinking from the cup without taking off the lid. This further reduces the risk of spilling. Anti-spill cups intended to be used by children as a transition between the nursing bottle and drinking from normal cups and glasses are, generally, further provided with a valve which seals off the drinking passage. In use, the valve opens in response to a suction force exerted by the child, producing a pressure drop across the valve. Due to the presence of such a valve, no or very little beverage leaks from the cup when the cup is held upside down, falls over or even when it is shaken. As, when drinking from such cups, a reduced pressure would occur in the cup, complicating further drinking, the lid in many anti-spill cups is also provided with a vent passage, via which vent passage ambient air can enter into the inside space of the cup in which the beverage is present. In order to also prevent spilling via the vent passage, this too is often provided with a valve, such as a one-way valve that only opens at a pressure drop from outside towards the inside space of the cup. With the cup according to the international patent application WO 93/19718 mentioned, the valve membrane plate, of which the valve membranes in the drinking passage and the vent passage form part, is designed as a disc-shaped element from, for instance, latex or silicon rubber with dome-shaped valve membranes, of which convex sides are turned in the respective flow direction when drinking and aerating and in which self-closing cuts are provided. A drawback of such self-closing slits is that either they do not seal off sufficiently firmly, or that, in open condition, they cause too much resistance. Further drawbacks are susceptibility to damage, wide range in closing and passage properties and complicated cleaning of the surfaces in the slits which, in a condition of rest, abut against each other. In the field of anti-spill cups, also, other membrane valves are used, such as for instance valves with a ring membrane which, in a condition of rest, seals off an opening of a passage. Such valves are for instance known from Dutch patent 1010555 and US patent application 2001/035420. Cleaning such valves is difficult too, and, in disassembled condition, the ring membranes can easily get lost.

SUMMARY OF THE INVENTION

It is an object of the invention to improve the cleanability of, in particular, the valve in the drinking channel of an anti-spill cup and, in addition, combine, in use, a limited resistance of the flow of beverage through the drinking passage with reliable sealing of the drinking passage. This object is achieved according to the present invention through the provision of an anti-spill cup according to claim 1. The invention can also be embodied in a valve assembly according to claim 13, which is specifically designed to be used as a part of such an anti-spill cup, integrated in a lid or as separate part which can be attached to a lid. Here, the confinement of the valve membrane plate between the form-retaining surfaces provides a bias at which, in a condition of rest, a valve membrane part of the valve membrane plate abuts in a reliably sealing manner around an opening of the drinking passage, against a valve seat remote from the cavity in flow direction. On an opposite side of the valve membrane remote from the valve seat, a free valve membrane lifting space is left clear, in which, in response to a pressure drop outwards across the valve membrane, the valve membrane is lifted for allowing the passage of beverage. The valve can be cleaned easily, in that in detached condition all surfaces of the valve membrane are freely accessible and in that surfaces of the Hd and of the valve membrane sealingly abutting against each other in the condition of use, are easily accessible when the fixation of the supporting surfaces is released. Special design aspects of the invention are laid down in the dependent claims. Further aspects, effects and details of the invention are elucidated on the basis of an exemplary embodiment with reference to the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a side view of an example of a cup according to the invention; Fig. 2 shows a perspective front view of a the cup of Fig. 1; Fig. 3 shows a side view in cross-section along the line IH-III in Fig. 4 of a top part of the cup according to Figs. 1 and 2; Fig. 4 shows a bottom view of a lid of the cup according to Figs. 1 - 3; Fig. 5 shows a perspective view of a bottom side of a holder of a valve assembly of the cup according to Figs. 1 — 4; Fig. 6 shows a view in conformity with Fig. 5, where valve membrane plate is placed and a closing plate is an a different, open position; Fig. 7 shows a view in conformity with Fig. 6, where closing plate is in a closed position; and Fig. 8 shows a perspective view of an example of a drinking cup according to the invention where the lid is replaced with a drinking ring. DETAILED DESCRIPTION

In Figs. 1 and 2 is represented in whole an example of an anti-spill cup 1 according to the invention. The cup 1 according to this example is composed of a holder 2 which bounds a cavity 3 for receiving a beverage 4 and has an open topside 5 (see Fig. 3). The beverage can be thin-bodied such as water, lemonade or milk, but can also be a more viscous substance such as yogurt or custard and may furthermore contain larger particles, such as porridge or particular types of fruit yogurt. On the holder, a lid 6 is detachably attached. In attached condition, the Hd 6 seals off the open topside 5 of the holder 2. According to this example, the lid is provided with an internal thread 7 which cooperates with the external thread 8 along the topside 5 of the holder 2. Furthermore, in the condition shown, between the lid 6 and the holder 2 an optional ring 9 is retained, bearing the handles 10 for holding the cup 1. Through the lid 6 extend a drinking passage 11 and a vent passage 12 which communicate with the cavity 3 when the lid 6 is in the attached condition. According to this example, the drinking passage 11 reaches from a passage 13 in a confining plate 14 to a restriction 15 in a drinking spout 16. The drinking spout facilitates drinking from the cup 1 and the restriction 15 prevents beverage from flowing from the spout without there being a flow rate through the drinking passage 11, in that in the restriction 15, a meniscus is formed. A drinking valve 17 seals off the drinking passage 11 and a vent valve 18 seals off the vent passage 12. The drinking valve 17 is designed to allow the passage of beverage 4 through the drinking passage in a flow direction (arrow 19) away from the cavity 3, in response to a pressure drop applied across the drinking valve 17 away from the cavity 3. As a result, in use, beverage 4 can flow out via the drinking passage 11 only when beverage 4 is sucked from the cup 1, but not when only a limited pressure drop prevails across the drinking valve 17, as is the case when tilting the cup 1 sideways, holding it upside down or even when shaking the cup 1. The vent valve 18 is designed to allow the passage of air through the vent passage 12 in a flow direction 20 towards the cavity 3, in response to a pressure drop applied across the vent valve 12 towards the cavity 3. With it, the vent valve 12 effects that during drinking, beverage volume flowing from the cavity 2 is replaced with inflowing ambient air, so that only a very limited reduced pressure is formed in the cavity 3 and drinking without pausing for allowing air into the cavity 3 is possible without this being complicated by an increasing reduced pressure in the cavity 3. According to this example, the vent passage 12 reaches from an entrance 21 to an opening 22 in the confining plate 14. The lid 6 is further provided with a valve membrane plate 23 forming a valve membrane 24 of the drinking valve 17 and a valve membrane 25 of the vent valve 18, and which is situated between form-retaining, mutually detachable fixed supporting surfaces 26, 27 of the lid 6. According to this example, one surface 26 hereof is formed by a surface 26 of the confining plate 14 facing the valve membrane plate 23, and the other surface 27 is formed by a surface 27 of a holder 28 facing the valve membrane plate 23, which holder forms a detachable part of the lid 6. The holder 28 is provided with sleeves 29, 30 which, in assembled condition, are clamped in sleeves 31, 32 formed on the lid 6. Such a holder 28 with valve assembly can be presented both together with an associated lid and separately. However, it is also possible to form a supporting surface, such as the surface 27, integrally with the lid. It is noted that form-retaining is understood to mean that the surfaces 26, 27 are sufficiently form-retaining to keep at least the relatively flexible membrane parts 24, 25 at a bias sufficient to obtain a sufficiently reliable sealing, and, when lifting the membranes 24, 25 so that the application of the bias ceases, to not move along such that this would disturb the operation of the valves 17, 18. The valve membrane 24 in the drinking passage 11, in its drinking passage 11 sealing condition, is biased around an opening 33 of the drinking passage 11, sealingly abutting against a substantially form-retaining valve seat 34. The valve seat 34 (which, for that matter, can also be designed as a flat or differently shaped surface) is located on the upstream side of the valve membrane 24. Within the framework of the invention it is possible to design the valve seat such that it, for instance, engages the walls of the opening in the valve membrane 24. In similar and other cases it may be so that the valve seat 34 is only located on the upstream side of the valve membrane 24 when the valve membrane 24 is opened over a substantial distance. On an opposite side of the valve membrane 24, remote from the valve seat 34, a free valve membrane lifting space 35 is situated. The valve seat 34 presses against the valve membrane 24 at a limited bias so that, in a condition of rest, it is held closed. The plate-shaped membrane 24 abuts against a form-retaining supporting surface 34 while the passages 33, 13 in the membrane 24 and in the supporting surface 34 are staggered relative to each other. If a child, wanting to drink from the cup 1 by sucking the spout 16 applies a pressure drop across the valve 24, the valve membrane 24 is displaced over a limited distance away from the valve seat 34, into the free valve membrane lifting space 35. As a result, the sealing around the opening 33 is released and beverage can flow through the drinking passage 11. When the mutual fixation of the supporting surfaces 26, 27 has been released, the membrane plate 23 can be taken out so that all sealing surfaces of the valve 24 become freely accessible and can be easily cleaned. As, here, the valve membrane plate 23 also forms the valve membrane 25 of the vent passage 12, only one valve membrane part 23 needs to be cleaned which, moreover, due to its relatively large dimensions, can be easily handled and is not easily lost. An additional advantage of a valve membrane 24 that closes because it is held at a bias against a valve seat 34 is that it is little sensitive to damage and, in opened condition, causes relatively little resistance. The drinking valve 17 being easily cleanable is of particular advantage because the drinking valve 17 is in the most intensive, direct contact with the drinking valve 17 and the beverage drunk by the child. However, the valve 18 in the vent passage 12 being easily cleanable is of importance too because, via inflowing air, contamination from the vent passage 12 is possible too. In order that the valve 18 in the vent passage 12 can also be cleaned in a simple manner, the valve membrane 25, in its vent passage 12 closing position, is biased around an opening 36 of the drinking passage 11, sealingly abutting against a further valve seat 37, and, on an opposite side of the valve membrane 25 remote from the further valve seat 37, a further free valve membrane lifting space 38 is situated. With this valve 18 too, the plate-shaped membrane 25 abuts against a form-retaining supporting surface 37 while the passages 36, 39 in the membrane 25 and in the supporting surface 37 are mutually staggered. Furthermore, the valve membrane plate 23 can be mounted between the supporting surfaces 26, 27 in different positions, whereby either the valve membrane 24 or the valve membrane 25 is located in the drinking passage 11. As the valve membrane plate 23 can be mounted between the supporting surfaces 26, 27 in at least two mutually different positions, while, with the valve membrane plate 23 mounted in one of these positions, a different valve membrane 24, 25 is located in at least one of the passages 11, 12 than with the valve membrane plate 23 mounted in another of the possible positions, the resistance experienced while drinking from the cup 1 can be adjusted. For consuming viscous beverages for instance, it is usually recommended to use a valve membrane with a relatively limited closing force and, hence, resistance in particular in the drinking passage 11, because, firstly, the suction required for sucking a viscous liquid through such a membrane valve is greater than the suction required for sucking up a thin-bodied liquid and, in order to somewhat counteract spilling of the viscous liquid, a more limited closing force can suffice than for counteracting spilling thin-bodied liquid. Furthermore, with the valve according to this example, the valve membrane 25 in the vent passage 12 and the valve membrane 24 in the drinking passage 11 have mutually different properties and the valve membrane plate 23 can be mounted between the supporting surfaces 26, 27 in a position rotated about a rotation axis situated centrally between the vent passage and the drinking passage. Therefore, when changing the mounted position of the valve membrane plate 23, this can be rotated such that the valve membrane 25 in the vent passage 12 and the valve membrane in the drinking passage 11 are mutually exchanged. The fact is that for determining the resistance experienced when drinking, the property of the valve that is in the drinking passage is predominant. When, out of two valves, the valve generating the most resistance is located in the drinking passage 11, more resistance is experienced when drinking from the cup 1 than when the valve generating the least resistance is located in the drinking passage 11. With the valve according to the example shown, the rotation axis about which the valve membrane plate 23 can be rotated extends in the plane of the valve membrane plate 23. As a result, when mounted in the other of the passages 11, 12, in which the flow direction is reversed, the valve membranes 24, 25 are reversed so that the valve membranes 24, 25 always open in the same direction, irrespective of them being located in the drinking passage 11 or in the vent passage 12. That is why the valve membranes 24, 25 can be optimized for one single direction of opening. The valve membrane plate 23 has a contour which is mirror symmetrical exclusively with respect to a plane 40 located centrally between the vent passage 12 and the drinking passage 11. As a result, when rotating between two mounted positions, the valve membrane 23 can only be mounted in the intended two positions for mounting in a correspondingly formed recess in the holder 28. It is, for that matter, also possible to provide that the correspondingly formed recess is recessed in the confining plate 14 or wholly or partially in both the confining plate 14 and the holder 28. It is noted that differences in resistance generated by the valve or valves when mounting the valve membrane plate in different positions can also be realized without different valve membranes being located in the passage or passages upon mounting in different positions. For instance, a valve membrane may be designed such that when mounted in the passage in the one position, it generates more resistance than when mounted in a different, for instance reversed position, for instance because the membrane abuts against the valve seat at a greater bias. One of the supporting surfaces 26 forms part of a closing plate 14 with a window 41 and the valve membrane plate is provided with indicators 42, of which a first one is visible via the window 41 with the valve membrane plate 23 in a first position between the supporting surfaces 26, 27, and another one (not visible in the drawing because on the bottom side of the valve membrane plate) is visible via the window 41 with the valve membrane plate 23 in a second position between the supporting surfaces 26, 27. As a result, the user can easily see whether the valve membrane plate 23 is mounted in a position in which relatively much, or relatively little resistance is experienced when drinking. With a device according to this example, dismantling and mounting the valve membrane plate 23 can be carried out in a simple manner in that the supporting surfaces 26, 27 are mutually connected by a hinge 43 (according to this example a film hinge) and because they are mutually pivotal about this hinge 43. Even when the mutual fixation, effected by a snap connection, of this confining plate 14 in relation to the holder 28 is released, the confining plate 14 remains connected to the holder 28 by it, so that the confining plate 14 is prevented from getting lost. Moreover, the hinge 43 forms a guide upon closing of the confining plate 14 so that incorrect mounting is prevented. As the openings around which, in sealing condition, the valve, membranes 24, 25, sealingly abut are openings 33, 36 in the respective valve membrane 24, 25, a bias on the closure is obtained, uniformly distributed around the opening, which bias forms a reliable seal until the intended pressure drop at which the valve membrane 24, 25 opens. Here, it is also advantageous that the valve membranes are retained along an annular contour 44, 45, in relation to which the openings 33, 36 are located centrally in the respective valve membrane 24, 25. With the anti-spill cup according to the example shown, the drinking passage 11 is located on a lateral side of the lid 6 adjacent an outside circumferential edge of the lid 6, an inside wall 46 of the holder 2 on the lateral side where the drinking passage 11 is located is more strongly bevelled than on least another lateral side, and the holder 2 has a foot part 47 which, on this lateral side, projects stronger from the inside wall 46 than on at least one other lateral side. These features, which can also be advantageously applied in combination with a another lid than the cup according to the present invention, and even without vent passage or even without Ud, offer the advantage that in order to drink the last liquid 4 from the cup, the cup 1 needs to be tilted less than other cups, but nevertheless stands relatively firmly. In Fig. 8, an example of a drinking cup according to the invention is represented, of which a drinking ring 49 instead of a Hd is screwed onto the top rim of the holder part 2 of the cup 1. With it, also the ring 9 from which the handles 10 project is fixed. Use of such a covering ring enables advantageous use of the drinking cup according to the invention, also when the drinking skill of a child has progressed so far that the child can drink from an open cup without too great a risk of spilling. With respect to drinking from a cup without covering, the covering 29 offers the advantage that it forms a smooth upper rim of the holder part 2 of the cup, so that drinking is more comfortable and there is less risk of beverage leaking away sideways than when drinking from a cup whose closing edge, such as a screw thread, is not covered. On the lateral side where the drinking passage is located, the foot part 47 has a cavity 48 open towards the bottom. This open cavity 48 can be positioned for receiving at least a part of the drinking spout 16 of a further anti-spill cup placed coaxially under the cup 1 and which is identical to the respective anti-spill cup 1.