Patent Publication Number: US-11661244-B2

Title: Liquid dispenser having compressible liquid store

Description:
FIELD OF APPLICATION AND PRIOR ART 
     The invention relates to a cream dispenser for dispensing liquids typically on the skin of a user. Dispensers of this type are used in the cosmetic and pharmaceutical sectors. 
     Cream dispensers of the generic type as well as cream dispensers according to the invention are typically configured as tube dispensers and, apart from the typically integral tube body, also comprise a plastics-material delivery head which is attached to the latter and has a delivery opening. The delivery head, for the purposes of avoiding drying-out and/or improving the standing capability of the dispenser, has a hinged lid which in the closed state covers a delivery opening. 
     A multiplicity of such cream dispensers of the generic type are known from the prior art. There nevertheless continues to be a demand for guaranteeing a high degree of comfort in terms of activation and a pleasant user experience at low production costs. 
     OBJECT AND ACHIEVEMENT 
     It is an object of the invention to make available a cream dispenser which is able to be produced in a cost-effective manner and which is distinguished by an operation and use which is pleasant in haptic terms. 
     To this end, according to a first aspect of the invention, a cream dispenser for dispensing liquid on the skin of a user is proposed according to the invention, said cream dispenser possessing a liquid reservoir having an outlet port, as well as a delivery head having an outlet duct and a delivery opening at the end of the outlet duct. The delivery head comprises an outlet valve having a valve pressure chamber, the outlet valve being able to be opened by the internal pressure of said valve pressure chamber. 
     A cream dispenser according to the invention is configured for dispensing highly viscous liquids, for example, cream-type or gel-type substances. The liquid reservoir of the dispenser according to the invention is accordingly filled with such a liquid, wherein this liquid can be a cosmetic liquid or a liquid effective as a pharmaceutical, or a hybrid liquid having both a cosmetic and a pharmaceutical purpose. 
     It is proposed that the delivery head comprises in particular two components, specifically an internal component and an external component. The external component has an end wall which is penetrated by the outlet duct and in which the delivery opening is provided. The internal component, for connecting to the outlet port of the liquid reservoir, comprises a connector port which extends in a direction of main extent (or longitudinally) of the dispenser. The internal component furthermore has a valve face which is disposed opposite an entry of the outlet duct, wherein the valve face and the entry of the outlet duct conjointly form the outlet valve and are mutually adapted in such a manner that the outlet valve can be opened and closed by repositioning the valve face and the outlet duct relative to one another. The internal component and the external component, along an encircling fastening region on an internal side of a casing face of the external component, are fixedly and tightly connected to one another so as to form a valve pressure chamber. 
     The internal component and the external component thus conjointly define the valve pressure chamber into which liquid from the liquid reservoir, in particular the tube, is squeezed. The rising pressure leads to the mutually opposite walls on the internal component and the external component becoming spaced apart, thus causing the valve to open. The cream can now exit in a metered manner through the delivery opening in the end wall. The cream thus particularly preferably reaches a planar external side of the end wall, from where the cream is applied to the skin of the user. The external side is therefore preferably free of sharp edges as the latter are considered unpleasant when in contact with the skin. 
     The delivery head comprises a hinged lid which in a closed state covers the delivery opening. The hinged lid on one side is provided with an articulation and opposite thereto is configured so as to have a first latching edge for fixing in a closing manner on the external component. The hinged lid herein is preferably an integral part of the external component. A substantially immovable part of the external component, conjointly with the internal component, forms a base of the delivery head, and the hinged lid has a movable part molded so as to be integral with the external component. 
     A release button is provided with a second latching edge and is provided on the immovable part of the external component. The second latching edge, in the case of a closed hinged lid, latches with the first latching edge on the hinged lid and via depression of the release button is releasable from this latching action such that the hinged lid can be opened. 
     The fastening region in which the internal component is fastened to the external component, in terms of the direction of main extent of the dispenser, is disposed so as to be level with the release button such that the release button when activated is moved in the direction of the fastening region. 
     The user depresses the release button in order for the hinged lid to be opened. It is desirable herein that such an activation runs smoothly in a comfortable manner without there being the risk of the release inadvertently taking place. 
     It is furthermore desirable that the depressing capability of the release button is delimited in a defined manner. This is achieved according to the invention in that the release button is moved in the direction of the fastening region. This fastening region of the delivery head has a high degree of stability since the internal component and the external component are connected to one another in this region. The mechanical coupling of the internal and external components reinforce this region. Additionally, the construction mode of the internal component as well as the choice of material for the latter can guarantee a particularly stable construction. 
     The release button is thus able to be depressed only to a limited extent until said release button is pushed against the stable fastening region and cannot be moved any further. This clear delimitation of the mobility is considered to be appealing in haptic terms and reduces the risk of the release button being accidentally broken off. 
     The external component and the internal component in the fastening region are preferably tightly connected by way of a snap-fit connection. One of the components, in particular the external component, to this end has an encircling groove into which an encircling web of the other component, in particular an external periphery of the internal component, is fixedly snap-fitted in a sealing manner. 
     The internal component preferably comprises an annular portion which extends transversely to the direction of main extent, and the external circumference of the annular portion in the fastening region is fixedly and tightly connected to the external component. This annular portion has a radial direction of extent which is counter to the depressing force acting on the release button, and thus has a particularly positive stiffening effect. 
     The external component is preferably made from a rather soft plastics material since this is advantageous in terms of the function of the articulation, in terms of the deformation capability of the release button, as well as in terms of the resilience of the end wall which is considered pleasant. In contrast, the internal component can be produced from a material which is more rigid and less elastic than that of the external component. This facilitates the assembly and simultaneously enhances the stiffness of the fastening region. 
     Alternatively or additionally, the internal component, at least in the region of the annular portion thereof, has a greater wall thickness than an end wall of the external component that, conjointly with the internal component, delimits the valve pressure chamber. This also enhances the flexibility of the end wall and the stiffness of the fastening region. 
     The internal component particularly preferably has a substantially flat area portion, the connector port rising from one side of the flat area portion and the external region of the latter forming the annular portion. The flat area portion on the opposite side thereof from the connector port is preferably provided with the valve face and at least one liquid passage. The internal component thus preferably has a fundamentally flat shape, only the connector port and optionally a structure which forms the valve face of the internal component rising from the fundamentally flat shape. 
     The release button can in particular be designed as a release tongue which is elastically molded on one side of the external component, the latching edge being provided on the distal end of said release tongue. It is preferably provided herein that the release button is separated from the surrounding casing face of the external component by a slot. This separation, by way of a slot in the case of the release button being linked only on one side to an at least partially surrounding casing wall, allows depression of the release button to be smooth. By virtue of the detent in the fastening region there is nevertheless no risk of the release button breaking off. 
     The hinged lid is preferably shaped in such a manner, or provided with an articulation of such a type, that the hinged lid in the closed state is biased and automatically springs open when there is pressure on the release button. Such a bias is advantageous, on the one hand, since the release button alone is sufficient for getting the dispenser to a delivery-ready state without the hinged lid having to be manually moved, in particular preferably pivoted by 180°, to the terminal position of said hinged lid. The bias is however furthermore advantageous since the bias keeps the latching connection between the hinged lid and the release button under tension. Despite the intended smooth running of the release button per se, any unintentional depressing of the release button is precluded. 
     In order to enable the hinged lid to spring open in an ideally complete manner, the articulation for linking the hinged lid is preferably conceived such that the articulation in the closed state is under tension, the latter relaxing in the course of the opening. 
     It is also particularly advantageous, in terms of the hinged lid springing open in a reliable self-acting manner, for the hinged lid to be under tension in the region of bearing contact with the end wall of the external component. The internal side of the hinged lid bearing on the end wall of the external component is already advantageous in terms of closing the delivery opening. On account of tension which thus is present in the end wall or the hinged lid, the opening is also facilitated in the manner described. 
     The hinged lid can in particular have a cover wall which covers the end wall of the external component. The side that points inward forms a closure face which is bulged in the direction of the delivery opening and, on account thereof, the cover wall in the closed state bears with bias on the end wall so as to surround the delivery opening. 
     The cover wall to this end has a size which preferably exceeds that of the end wall. The cover wall, at least on the internal side in the region of the closure face, particularly preferably however internally and externally, is configured so as to be free of additional structures such as elevations or depressions, and thus deviates from a completely flat shape only by way of the bulge in the direction of the delivery opening. 
     On account thereof, the internal side that forms the closure face is easy to be relieved of the remnants of liquids. An encircling casing wall, on which the articulation and the latching edge proximal to the hinged lid are provided, preferably adjoins the cover wall externally. 
     The fastening region which, in the manner mentioned above facilitates the stability of the delivery head, in terms of the direction of main extent, is formed by the region in which the internal component and the internal side of the external component bear on one another and, on account thereof, achieve a fixed and liquid-tight connection. 
     The release button, in terms of the direction of main extent, preferably extends on both sides of this fastening region. The release button originates at the liquid reservoir and extends beyond the fastening region. Alternatively, the release button can, however, also be provided that the end of the release button that points away from the liquid reservoir and/or the latching edge on the release button extend/extends only up to the fastening region but not beyond the latter. 
     According to a further aspect of the invention, a cream dispenser for topically dispensing liquid on the skin of a user is proposed, the cream dispenser possessing a liquid reservoir having an outlet port and a delivery head having an outlet duct and a delivery opening at the end of the outlet duct. This delivery head has an end wall which is penetrated by the outlet duct and in which the delivery opening is provided. 
     The delivery head comprises a hinged lid which in a closed state closes the delivery opening. The hinged lid on an internal side herein has a bulged closure face, the size of the latter being larger than the cross-sectional area of the delivery opening, wherein the bulged closure face in the closed state of the hinged lid, in the region of an annular contact face that surrounds the delivery opening, bears on the end wall. 
     The bulged closure face on account thereof additionally closes the delivery opening and can additionally somewhat depress the end wall so as to effectively preclude an outlet valve of the delivery head being opened. The bulge is preferably achieved in that the cover wall in its entirety is bulged in the region of the closure face such that the external side that is opposite the closure face also has this bulge. The cover wall in this instance preferably has a uniform (+/−10) wall thickness. Alternatively, however, designs in which the closure face per se, but not the opposite external side of the hinged lid, is bulged are also possible. In this case, the wall thickness in a centric region of the closure face is preferably greater than in a peripheral region of the closure face or than in an annular region that surrounds the closure face. 
     The closure face may be formed only by partial regions of the internal side of the end wall which are bulged convexly when seen from the perspective of the delivery opening, thus by a face which is opposite the delivery opening and in the closed state bulges in the direction of delivery opening. The curvature radius herein, at least in the region of the annular contact face, is comparatively large, the curvature thus being minor. The curvature radius at least in the region of the annular contact face, preferably however in terms of the entire closure face, herein is in particular between 4 cm and 25 cm, preferably between 6 cm and 15 cm. These values relate to the open state of the hinged lid, and thus exclude any deformation caused by the closed state. 
     The curvature has the effect that the contact face between the closure face and the end wall is minor such that a comparatively high contact pressure per unit area is achieved. The annular contact face in the radial direction in terms of the delivery opening preferably has a width of less than 0.8 mm, in particular of less than 0.4 mm. The comparatively small contact face facilitates the tightness. Even if liquid under intense and unintentional pressure on the liquid reservoir can actually exit through the delivery opening in the case of a closed hinged lid, the liquid only reaches this annular contact face. This liquid can later be very easily removed by virtue of the internal side of the hinged lid being preferably free of edges. 
     The closure face is larger than the delivery opening so as to enable the delivery opening to bear in a surrounding manner on the end wall. The closure face is particularly preferably at least 20% larger, preferably at least 40% larger, than the cross-sectional area of the delivery opening, in order for the closure face in its entirety not to invade the delivery opening but to in any case protrude beyond the periphery of the latter. 
     The closure face, which is formed by a convexly bulged part of the internal face of the end wall of the hinged lid, is preferably even significantly larger. The closure face particularly preferably forms the entire internal face on the internal side of a surrounding lid periphery, or almost the entire internal face. This means that at least 80% of the internal side of the cover wall is preferably formed by the bulged closure face. The curvature radius on this at least 80% of the internal side of the cover wall is preferably without exception in the above-mentioned range between 4 cm and 25 cm, and particularly preferably between 6 cm and 15 cm. 
     The bulged closure face being completely formed in such a way by the internal side of the cover wall leads to the entire internal side being very easy to clean since the internal side, by virtue of the mentioned curvature radius range, does not have any kind of steps or cracks which are difficult to clean. 
     A design of the hinged lid in which the entire cover wall, or almost the entire cover wall, on the internal side forms the bulged closure face and where the wall thickness is uniform (+/−10%) permits in particular a uniform tension in the hinged lid in the closed state such that the hinged lid, proceeding from the closed state, when the hinged lid is released, for example by way of the release button already described, springs to a position which completely releases the end wall. 
     A further aspect of the invention relates to the attachment of the hinged lid to the base of the delivery head. All above-mentioned measures can be additionally provided in a mutually independent manner herein. 
     According to this further aspect of the invention a cream dispenser for dispensing liquid on the skin of a user is proposed, the cream dispenser possessing a liquid reservoir having an outlet port as well as a delivery head having an outlet duct and a delivery opening at the end of the outlet duct. This cream dispenser is in particular designed according to the manner described above. 
     The delivery head, with the exception of a minimal movement for opening a valve or for depressing the release button, has a substantially immovable base. The base, for connecting to the liquid reservoir, comprises a connector port which extends in a direction of main extent and furthermore comprises an end wall which is penetrated by the outlet duct and in which the delivery opening is provided. A delivery of liquid initially takes place to the external side of the end wall and the liquid from there is then applied to the skin of the user. 
     The formation of the delivery head having an internal component and an external component is not primarily relevant in this aspect of the invention. Nevertheless, the base is preferably likewise constructed from these two parts. 
     The delivery head according to this further aspect likewise comprises a hinged lid which in the closed state covers the delivery opening and the end wall and which by means of an articulation is articulated so as to be pivotable on the base. Interacting latching edges are provided so as to be opposite the articulation on the base and the hinged lid, by means of which latching edges the hinged lid in the closed state can be latched on the base. The latching edge on the base and the articulation, in terms of the direction of main extent, are disposed so as to be mutually offset such that the latching installation on the hinged lid in the completely pivoted-open state, in terms of the direction of main extent, is more remote from the delivery opening than in the closed state of the hinged lid. 
     The hinged lid, which can have all aspects which have been described above in the context of the first aspect of the invention, is preferably pivotable by approximately 180° (+/−20°) between the closed position and the maximum pivoted position. The articulation, and in particular the pivot axis defined by the articulation, on the one hand, and the latching edge for latching on the base, on the other hand, are mutually offset in terms of the direction of main extent. 
     This offset leads to the latching edge of the hinged lid with a swung-open hinged lid being recessed particularly far in relation to an end wall of the base. This is advantageous in terms of a pleasant use, since cream which has initially been delivered to the end wall of the base from the latter can be applied on the skin of a user, and the risk of the comparatively sharp-edged latching edge of the lid inadvertently also coming in contact with the skin is reduced. 
     The latching installation on the base and the articulation in terms of the direction of main extent are preferably disposed to as to be mutually offset by at least 3 mm, preferably by at least 5 mm. 
     In order for the desired effect, i.e. the ideally large spacing of the latching edge on the lid from the plane of the end wall of the base in the swung-open state, to be reinforced, the articulation and the pivot axis defined by the latter in terms of the direction of main extent are disposed so as to be as close as possible to the liquid reservoir. The spacing from an end of a casing face of the delivery head pointing in this direction is preferably 5 mm or less. It is furthermore advantageous for the latching edge of the base, in terms of the main direction of extent, to be as remote as possible from the liquid reservoir. It is considered advantageous for the latching edge to be only slightly recessed, particularly by less than 3 mm, from the external face of the end wall. However, the spacing should ideally not be less than 1 mm in order for the latching edge of the base not to come into contact with the skin when cream is applied on the skin. 
     A bearing edge, on which an encircling casing face of the hinged lid bears in the closed state, is preferably provided on both sides on the external side of the external component. The bearing edges herein are configured as edges which gradually rise from the articulation toward the latching installation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and aspects of the invention are derived from the claims and from the description hereunder of preferred exemplary embodiments of the invention that will be explained hereunder by means of the figures in which: 
         FIG.  1    shows a cream dispenser according to the invention in an overall illustration; 
         FIG.  2    shows an exploded illustration of the cream dispenser according to  FIG.  1   ; 
         FIGS.  3  and  3 A  show the cream dispenser in a sectional illustration with the lid opened; 
         FIG.  4    shows the cream dispenser in a sectional illustration with the lid closed; 
         FIGS.  5 A and  5 B  show the interaction of a hinged lid of the cream dispenser and an end face which surrounds the delivery opening for the purpose of closing the delivery opening; and 
         FIGS.  6  and  7    show variations of the cream dispenser of  FIGS.  1  to  5 B , the variations differing from the preceding design in terms of the design of the hinged lid and the closure face provided thereon. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     The figures highlight the construction of a cream dispenser according to the invention. 
       FIG.  1    shows the cream dispenser  10  in the shipped state. The cream dispenser  10  comprises a liquid reservoir  12  which presently is configured as a tube and thus is provided for activation by manually impinging the external faces with pressure. In principle, however, other concepts are also conceivable, for example having a repositionable piston which at the end side is pushed into the liquid reservoir in order to convey liquid out of the latter. 
     A delivery head  20  is attached to the liquid reservoir  12 , for example by means of a threaded connection or a snap-fit connection. The delivery head comprises a base which when in operation remains so as to be substantially immovable in relation to the liquid reservoir, and a hinged lid  60  which in the closed state covers a delivery opening  44  and can be unlatched and opened by means of a release button  48 . 
       FIG.  2    shows the individual component parts of the cream dispenser  10 . The liquid dispenser  12  in the state of  FIG.  2    is still situated in the unfilled state and at the lower end thereof that is opposite an outlet port  14  is therefore not yet closed. 
     As is highlighted in  FIG.  2   , the delivery head  20  has two components  30 ,  40 , specifically an internal component  30  and an external component  40 . The internal component herein is configured so as to have thicker walls and/or from a stiffer material, forming the less deformable one of the two components  30 ,  40 . 
     The internal component  30  in the assembled state is fixedly connected to the external component  40 . The internal component  30  furthermore has a connector port  32  which is configured for coupling to the outlet port  14  of the liquid dispenser  12  by means of a threaded connection or a snap-fit connection. The outlet port  14  in the illustrations is illustrated in a simplified manner, without a thread or a snap-fit edge. 
     The detailed construction of the delivery head and of the two components  30 ,  40  can be derived from the following figures. 
       FIGS.  3  and  3 A  show the delivery head  20  in the ready-to-use opened state. It can be seen that the external component  40  has a casing wall  46  which at the end side is adjoined by an end wall  49 . This end wall  49  is penetrated by the outlet duct  42  which opens into the delivery opening  44 . The end wall  49  is configured externally so as to be almost flat and is only slightly concavely bulged. The external side is externally free of elevations or depressions such that cream that has previously been delivered to the end wall can herewith be applied from here to the skin. 
     The casing wall  46  in the region of the release button  48  is provided with a slot  47  which separates the release button  48  laterally and toward the top from the surrounding wall and thus permits the release button  48  to move freely. 
     The internal component  30  is connected to the external component  40  in order to conjointly form a valve pressure chamber  52 . To this end, an outer periphery in the region of the external circumference  36 A of an annular portion  36  of the internal component  30  latches into a groove on the internal side of the casing wall  46  of the external component  40 . This contact region forms the fastening region  46 A in the context of the invention. The connection between the external component  40  and the internal component  30  in the fastening region  46 A according to the intended use is non-releasable and tight. Liquid from the liquid reservoir that reaches the valve pressure chamber  52  by way of liquid passages  33  in the internal component  30  can thus exit only through the delivery opening  44 . 
     The outlet duct  42  which penetrates the end wall  49 , as well as a valve face  34  on a frustoconical elevation which is provided so as to be centric on the internal component  30 , conjointly form an outlet valve  50  which is closed on account of the slightly biased shape of the end wall  49  in the resting position. When liquid in the liquid reservoir  12  is impinged with pressure, in particular by compressing the tube, the pressurized liquid reaches the valve pressure chamber  52  and leads to the end wall  49  being deformed toward the outside. The outlet valve  50  is opened on account thereof, and the liquid can reach the external side of the end wall  49 . The application directly onto the skin can take place from there once a sufficient amount of liquid has been delivered to the end wall  49 . 
     As has already been mentioned, the delivery head  20  comprises a hinged lid  60 . The latter, in the design described here, is configured as an integral part of the external component and is linked to the latter by means of an integrally configured articulation  62  in the manner of an integral hinge. Alternatively however, a design in multiple parts is also possible. 
     The hinged lid  60  comprises a slightly concavely bulged cover wall  64 , the internal side of the latter being configured so as to be larger than the end wall  49  of the delivery head. The internal side of the cover wall  64  is surrounded by a casing wall  61  and on the inner side thereof does not have any elevations which go beyond the bulged basic shape of the cover wall  64 . This leads to remnants of cream being able to be easily removed here. 
     The release button  48  which has already been described is provided for opening the hinged lid  60 . In the closed state which is illustrated in  FIG.  4   , a latching edge  48 A at the distal upper end of the release button latches with a corresponding latching edge  66  on the hinged lid  60 . Since the lid in the region of the cover wall  64  thereof is biased, the latching action in the closed state is rather strong, and there is no risk of any unintentional depressing of the release button  48  and of opening the hinged lid. However, this is readily possible in a manner which is pleasant in haptic terms when the release button  48  is manually and intentionally activated. The release button  48  is cut out on three sides by the slots  47  and can thus be easily depressed. Any excessive depressing action of the release button  48  is thus avoided in that the release button  48  externally impacts the fastening region  46 A in the manner highlighted by the dashed lines in  FIG.  3 A . 
     The hinged lid  60  springs open as soon as the latching edges  48 A,  66  have been disengaged on account of the depressing action. On account of the bias in the region of the cover wall  64  as well as on account of a suitably biased design of the articulation, the opened state of  FIG.  3   , in which the hinged lid  60  is pivoted by approximately 180°, can be achieved solely by pressure on the release button  48 . 
       FIG.  3    herein highlights the relative disposal of the latching edges  48 A,  66 , on the one hand, and of the articulation  62 , on the other hand. In terms of the direction of main extent  2  and the closed state, the articulation  62  is disposed so as to be significantly closer to the liquid reservoir  12 , thus further down in the perspective of  FIG.  3   , than the latching edges  48 A,  66 . The offset, which (in terms of the direction of main extent) presently is approximately 6 mm, leads to the latching edge  66  in the opened state being spaced apart from the plane of the external side of the end wall  49  by more than double this amount, which is approximately 13 mm. 
     This enables the cream which previously has been delivered to the external side to be applied to the skin without the risk of the rather sharp-edged latching edge  66  contacting the skin. 
     The hinged lid  60 , which in the closed state is under tension, by means of an internal side which forms a closure face  65  closes the delivery opening  44 . This will be explained once again in more detail by means of  FIGS.  5 A and  5 B . The internal side of the cover wall  64  in its entirety up to the lateral casing wall  61  forms a bulged closure face  65  having a largely uniform curvature radius of approximately 12 cm. The cover wall  64  has a uniform wall thickness and is also bulged in an approximately uniform manner on the entire external face  67  which is opposite the closure face  65 . 
     In the closed state of  FIG.  5 A , the closure face  65  bears on a comparatively small annular contact face  43  on the end wall  49  which is penetrated by the delivery opening  44 , in addition to the outlet valve  50  thus preventing the exit of liquid. In particular, neither an unintentional compression of the tube  12  nor an increase in the pressure in the valve pressure chamber  52  can lead to liquid exiting through the delivery opening  44 , since the outlet valve  50  is pushed to the closed position thereof by the closure face  65  of the cover wall  64  which is under tension. 
     The design of the cover wall  64  having a uniform wall thickness as well as having a bulged closure face  65 , the latter forming the entire internal side of the cover wall  64 , is considered advantageous in order for the desired closing tension to be achieved and for easy cleaning of the internal side to be enabled. 
     However, alternative designs in which the bulged closure face  65  only forms a centric central region of the internal side of the cover wall  64  and externally is surrounded by an annular region which is planar, for example, or bulged in the reverse manner, are also conceivable.  FIGS.  6  and  7    show such designs. 
     Such a planar annular region  68  which forms the external region of the cover wall  64  and extends across approximately 45% of the radius is provided in the design of  FIG.  6   . The bulged closure face  65  is provided only internally in terms of the planar annular region  68 , the bulged closure face  65  in a corresponding manner having a somewhat smaller curvature radius than the closure face of the preceding design. The curvature radius in this design is approximately 7 cm. While the cleaning of the internal side formed by the closure face  65  and the annular region  68  is not quite as easy as in the preceding design, the design according to  FIG.  6    in technical terms is also advantageous in comparison to known solutions. 
     In the design of  FIG.  7   , the internal side of the cover wall  64  is shaped like in the design of  FIG.  6   . Deviating from the latter design, however, no uniform wall thickness is provided here. The external side of the cover wall  64  that is opposite the closure face  65  is configured so as to be planar in this design. When the hinged lid  60  is closed and bears on the end wall  49  in the region of an annular contact face  43 , this leads to a deformation primarily taking place in the thinner annular region  68  which surrounds the closure face  65 .