Abstract:
A leak resistant drinking cup has a diaphragm seal for normally closing an open top of a liquid container of the cup. The seal can be opened to permit liquid to flow past it and out of the cup upon application of a vacuum pressure by the person, typically a small child, drinking from the cup. The diaphragm seal has a peripheral edge margin that can be deflected upward by the vacuum pressure to open a path out of the drinking cup. A hold down rib may be employed to control the locations where the peripheral edge margin is permitted to deflect.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates generally to leak resistant vessels and more particularly to vessels which permit, in a controlled manner, passage of liquid out of the vessel upon demand.  
         [0002]     Vessels of the type to which the present invention relates are most commonly in the form of drinking cups used for small children. The cups are configured so that if they are turned over, liquid inside the cup is prevented from spilling out of the cup by a valve arrangement that seals the cup when not used. Usually the cup has a relatively rigid cover formed with a spout that the child puts his lips on to drink from the cup. The cover can be releasably attached (e.g., snapped or screwed on) to a container portion of the cup over an open top of the container portion, to close the open top. The valve is arranged between the cover and the container portion can be opened to allow liquid to pass out of the cup for drinking. Most commonly, the valve is actuated by a vacuum pressure applied by the user to the interior of the cup by sucking on a spout or other opening in a cover of the cup. The vacuum pressure so applied causes the valve to move or deform in such a way that a path past the valve is exposed so liquid can flow out of the cup. It is possible that the valve might be actuated in other ways, such as a purely mechanical actuation, but for small children vacuum pressure actuation is most preferable because the only time the valve is open is when the child in the act of taking a drink.  
         [0003]     Vacuum pressure actuated drinking cups of the type just described have certain problems generally associated with balancing the need to assure positive sealing with the need to make the cup easy to use for the child. A strong seal by the valve requires a relatively large vacuum to open, making it hard for the child to use. A seal that requires a lower vacuum pressure to open may not seal tightly enough to prevent at least some liquid flowing past it. Frequently, the valve is relatively small and located under the spout. The small size of the valve requires a substantial vacuum pressure to actuate because the pressure acts on only a relatively small area. In other words, children will have to suck with significant effort to get the valve to open. That makes the cup less desirable to the child. It is also important to reduce the opportunity for the child to suck in air when drinking from the cup. This may occur when the level of liquid in the cup is low. If the opening covered by the valve is relatively small, the problem is minimized. However if the valve is also small in surface area, this can lead to difficulty in opening the valve, as previously described.  
         [0004]     Conventionally, the valve may be permanently attached to the cover so that the valve will always remain in tact. However, in use the valve will necessarily become fouled with drink liquid and particulates in the liquid. Although cleaning is possible, it is very difficult to clean the entire valve or the entire cover. Disassembly of the valve from the cover would result in destruction of the valve (or cover). Therefore, it is difficult to make certain that the valve and cover remain clean in repeated use. It is known to provide valves that can be disassembled from the cover for cleaning. However, these valves may be difficult to detach and reassemble. Moreover, small valves may become lost or damaged.  
       SUMMARY OF THE INVENTION  
       [0005]     In one aspect of the present invention, a leak resistant drinking cup generally comprises a container sized and shaped for receiving and holding a quantity of liquid for drinking. The container has an open top. A lid assembly includes a cover adapted for removable attachment to the container for closing the open top, the cover having a rigid spout for receiving the drinking liquid through the cover. A flexible diaphragm seal adapted to be disposed between the cover and the open top of the container is able to selectively block the flow of liquid from the container to the spout in the cover. The diaphragm seal has a peripheral edge margin adapted to, as installed between the cover and the container, flex between a closed position in which the diaphragm seal blocks movement of the drinking liquid from the container to the spout of the cover, and an open position in which the diaphragm does not block the drinking liquid flowing from the container to the spout.  
         [0006]     In another aspect of the present invention, a leak resistant vessel generally comprises a container sized and shaped for receiving and holding a quantity of liquid. The container has an open top and a central axis. A lid assembly includes a cover adapted for removable attachment to the container, the cover having an opening for receiving the liquid through the cover. A flexible diaphragm seal adapted to be disposed between the cover and the open top of the container is able to selectively block the flow of liquid from the container to the opening in the cover. The diaphragm seal has a peripheral edge margin capable as installed between the cover and the container of flexing between a closed position in which the diaphragm blocks movement of the liquid from the container to the opening of the cover, and an open position in which the diaphragm does not block the liquid flowing from the container to the cover opening. A hold down is sized and shaped for holding down a portion of the diaphragm seal when assembled on the container to hold the diaphragm seal portion against flexing from the closed position to the open position while permitting another portion of the diaphragm seal to flex from the closed position to the open position upon application of a vacuum pressure between the cover and the diaphragm seal.  
         [0007]     Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a perspective of a leak resistant drinking cup;  
         [0009]      FIG. 2  is an enlarged vertical section of the cup;  
         [0010]      FIG. 3  is the vertical section of  FIG. 2 , but illustrates the configuration of a diaphragm seal of the cup when a vacuum is applied for drawing liquid out of the cup;  
         [0011]      FIG. 4  is an exploded perspective of the cup;  
         [0012]      FIG. 5  is a bottom perspective of the diaphragm seal;  
         [0013]      FIG. 6  is a bottom perspective of a retainer of the cup;  
         [0014]      FIG. 7  is a bottom perspective of a cover of the cup;  
         [0015]      FIG. 7A  is a bottom plan of the cover;  
         [0016]      FIG. 8  is a vertical section of a drinking cup of a second embodiment;  
         [0017]      FIG. 9  is a bottom perspective of a retainer of the cup of  FIG. 8 ;  
         [0018]      FIG. 9A  is a top plan of the retainer of  FIG. 9 ;  
         [0019]      FIG. 10  is a vertical section of a drinking cup of a third embodiment;  
         [0020]      FIG. 11  is a top perspective of a retainer of the cup of  FIG. 10 .  
         [0021]      FIG. 12  is a vertical section of a drinking cup of a fourth embodiment;  
         [0022]      FIG. 13  is a bottom plan of a cover of the drinking cup of  FIG. 12 ;  
         [0023]      FIG. 14  is an elevation of a drinking cup of a fifth embodiment including a handle unit that has been partially broken away; and  
         [0024]      FIG. 15  is a cross section of the handle unit.  
     
    
       [0025]     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION  
       [0026]     Referring now to the drawings and in particular to  FIGS. 1, 2  and  4 , a drinking cup of a first embodiment (generally indicated at  1 ) constructed according to the principles of the present invention is shown to comprise a container (generally indicated at  3 ) having a closed bottom  5  and an open top  7  for holding a quantity of liquid to be consumed by a user, such as a small child (not shown). A lid assembly  9  comprises a cover  11  and a retainer  13  made of a suitable material such as polypropylene (the reference numbers indicate their subjects generally). A flexible diaphragm seal indicated generally at  15  is disposed between the cover  11  and an interior space of the container  3 . The diaphragm seal  15  can be made of silicone or other appropriate material. The cover  11 , retainer  13  and diaphragm seal  15  can be made any desired color or colors, and may be transparent or translucent. As described more fully hereinafter, the diaphragm seal  15  is operable to block the flow of liquid from the container  3  to prevent the liquid from being spilled if the cup is tipped over. The diaphragm seal  15  can be deflected or flexed by an application of vacuum pressure to permit liquid in the container  3  to flow past it to the cover  11  and out of the cup. In the most preferred embodiments, the present invention takes the form of a drinking cup for children (e.g., drinking cup  1 ). However it is to be understood that the principles of the present invention are applicable to cups for older children or adults, and to vessels which may be used for containing something other than consumable liquids.  
         [0027]     The container  3  is generally cylindrical in shape and generally symmetrical about a central axis A. It will be appreciated that a container (not shown) may be other than cylindrical and have a central axis. Such a container need not be symmetrical about the central axis within the scope of the present invention. The container  3  has an annular inner rim  21  and an annular outer attachment collar  23  at its upper end. The inner rim  21  forms a smooth continuation of an inner surface  25  of the container  3 . The attachment collar  23  has threads  27  formed on an outer surface for use in releasably attaching the cover  11  to the container  3 . When attached to the container  3 , an upper edge of the collar  23  sealing engages the cover  11 . An annular channel  29  in the upper end of the container  3  separates the inner rim  21  from the attachment collar  23  and allows the inner rim to be relatively thin and have a narrow upper edge  31  (see  FIG. 4 ) to facilitate sealing with the diaphragm seal  15 , as will be described more fully hereinafter. The container  3  is made of a suitable material, such as polypropylene, and may be of any desired color or colors, and may be transparent or translucent.  
         [0028]     The cover  11  of the lid assembly  9  includes a peripheral skirt  35  that has threads  37  on an inwardly facing surface to mate with the threads  27  on the attachment collar  23  of the container  3  ( FIG. 2 ) to allow the cover to be screwed onto and off of the container. Other forms and structures for making a releasable connection between the cover and the container (not shown) may be used without departing from the scope of the present invention. For instance, a cover and container may be constructed to permit a releasable snap-on attachment of the cover to the container. Referring now also to  FIGS. 7 and 7 A, a shallow conical portion  39  of the cover  11  is located immediately inward of the skirt  35  and surrounds short, tubular center aperture  41  in the cover. The cover  11  also has an upstanding spout  43  that defines an opening  45  through the cover. An opening may be defined by structure other than a spout (e.g., by a simple hole in a cover) within the scope of the present invention. The spout  43  is relatively rigid in the illustrated embodiment, but the spout or even the entire lid assembly  9  may be made to be highly flexible. The spout  43  protrudes upward from the remainder of the cover  11  and provides a structure for the child to place his lips around for sealing his mouth with the spout to apply suction to the drinking cup  1  for taking liquid from the drinking cup. The shape of the cover is preferably suitable for making connection to the container, but may otherwise take on shapes and configurations other than shown in the illustrated embodiments of the present invention.  
         [0029]     As best seen in  FIGS. 7 and 7 A, the underside of the cover  11  is formed with a rib  49  (broadly, a “hold down”) that is used for selectively holding down a portion of the diaphragm seal  15 , as will be described more fully. The rib  49  depends from a bottom surface of the cover  11  and extends continuously in a ring around a center C 1  of the cover. However, the rib  49  is eccentric from the center of the cover  11 . A center C 2  of the ring formed by the rib  49  is offset so that center C 2  and the spout  43  are located on radially opposite sides of the center C 1  of the cover  11 . Thus, the rib  49  is shifted away from the spout  43  so that more of the rib is on one side of the cover  11  (away from the spout) than the other, for reasons that will be set forth hereinafter. Although the rib  49  is continuous and formed as one piece of material with the cover  11 , a hold down (not shown) could be formed as a separate piece, and/or could be made up of multiple separate pieces between the cover and diaphragm seal  15  without departing from the scope of the present invention. Moreover, in addition to or instead of the rib  49  being eccentrically arranged on the cover  11 , the rib could be reduced in height on the side nearest the spout  43 .  
         [0030]     The retainer  13  of the lid assembly  9  comprises a base  53 , a mounting flange  55  and an annular neck  57  projecting upward from the base and flange that is received inside the central aperture  41  of the cover  11 . The base  53  has an air hole  59  through it for permitting air to pass from a location exterior of the container  3  into the interior of the container. As may be seen in  FIG. 6 , the air hole  59  is offset to one side of a center of the base  53 . An annular seat  61  is formed around the center of the base  53  for use in sealing off the air hole  59  from the interior of the container  3 , as will be described more fully hereinafter. The neck  57  is fixedly attached to the cover  11  in the central aperture  41  such as by welding or gluing. It will be appreciated that the retainer  13  may be releasably attached to the cover  11  without departing from the scope of the present invention. The cover  11  and retainer  13  of the lid assembly  9  are formed separately in the illustrated embodiments for convenience in manufacturing, but the two may be formed as a single piece. Thus, the lid assembly  9  can include only one component part in the present invention. It is desirable that the cover  11  and retainer  13  be formed as a unit in the finished drinking cup  1  to reduce the number of component parts of the drinking cup to be handled by the care givers of the child using the cup. The mounting flange  55  projects radially outwardly from the lower end of the central aperture  41  of the cover  11  and is used to mount the diaphragm seal  15  on the lid assembly  9 .  
         [0031]     The diaphragm seal  15  has a roughly saucer shape including an annular flange having a generally flat peripheral edge margin  65  and a shallow cylindrical central portion (indicated generally at  67 ). The central portion includes a circular bottom wall  69  (broadly, “a sealing section”) having a central air hole  71 . A side wall  73  of the central portion  67  is shaped to define an annular mounting recess  75  immediately adjacent to the bottom wall  69 . The diaphragm seal  15  can be snapped onto and off of the retainer  13  so that the mounting flange  55  of the retainer is received in the mounting recess  75  of the diaphragm seal. A tab  77  ( FIGS. 4 and 5 ) is formed on the bottom wall  69  of the diaphragm seal  15  to facilitate gripping for pulling the diaphragm seal off of the retainer  13 . The tab  77  may be omitted without departing from the scope of the present invention. The resiliency of the diaphragm seal material holds the seal  15  on the mounting flange  55 . It is easy to attach the diaphragm seal  15  to the retainer  13 , and to remove it again. Thus, the construction permits the separable components of the drinking cup  1  (i.e., the container  3 , the cover  11  and the diaphragm seal  15 ) to be taken apart for thorough cleaning and to be readily reassembled for the next use. The separable components are all relatively large so that they are easy to handle and are not easily lost. The bottom wall  69  of the diaphragm seal  15  bears against the annular seat  61  formed on the underside of the retainer  13  and seals against the seat. Thus, the air hole  59  in the retainer  13  is blocked from fluid communication with the air hole  71  in the bottom wall  69  of the diaphragm seal  15 .  
         [0032]     When the lid assembly  9  carrying the diaphragm seal  15  is screwed onto the container  3  as shown in  FIG. 2 , the underside of the peripheral edge margin  65  of the diaphragm seal flange engages the top edge  31  of the inner rim  21  of the container and seals with the inner rim. The peripheral edge margin  65  is driven down far enough by the cover  11  so that the inner rim  21  deflects the peripheral edge margin upward very slightly, causing the peripheral edge margin to bear against the inner rim and seal with the inner rim. The bottom wall  69  seals with the seat  61  to block the interior of the container  3  from the air hole  59 . It will be appreciated that the diaphragm seal  15  seals the open top  7  of the container  3  so that liquid in the container cannot flow past the diaphragm seal and out of the drinking cup  1 . Thus, if the drinking cup is upset or turned upside down, liquid in the container  3  will not spill out of the spout  43  or air hole  59 .  
         [0033]     Referring now also to  FIG. 3 , it is easy for a small child to get a drink out of the drinking cup  1  by placing her lips on the spout  43  so as to form a seal with the spout, and sucking. Sucking air from a space  81  (or “vacuum chamber”) between the cover  11  and the diaphragm seal  15  creates a vacuum in the space. Because of the shape of the cover  11 , the space  81  is located directly over the peripheral edge margin  65  of the diaphragm seal flange. The space  81  is generally annular and extends between an interior wall of the central aperture  41  and the skirt  35  of the cover  11 . The air pressure within the container  3  pushes on the underside of the peripheral edge margin  65  which deflects upward from the sealed position shown in  FIG. 2 , to an unsealed position shown in  FIG. 3 . Liquid is now permitted to flow past the diaphragm seal  15  at the inner rim  21  of the container  3  to the spout  43  for drinking as indicated by the arrows in  FIG. 3 . The liquid is able to flow directly along the inner surface  25  of the container  3  because the diaphragm seal  15  engages the upper edge  31  of the inner rim  23  that is a smooth continuation of the inner surface. This makes it easier to empty the entire liquid content of the container  3  without changing the angle at which the cup  1  is held.  
         [0034]     The peripheral edge margin  65  is not allowed to open everywhere, and particularly not in regions which are radially opposite from the spout  43 . This prevents the child from sucking in air from the container  3 , which is particularly a problem as the container is increasingly emptied of liquid. Keeping the peripheral edge margin  65  sealed with the inner rim  21  in locations away from the spout  43  is accomplished by the hold down rib  49  that depends from the bottom of the cover  11 . The rib  49  engages the top surface of the peripheral edge margin  65  in certain places to hold it down against the inner rim  21  of the container  3  even when vacuum pressure is present in the space above the peripheral edge margin. As previously described, and shown in  FIG. 7A , the rib  49  is eccentric of the center of the cover  11 , and thereby offset away from the spout  43 . It will be understood that a rib of the present invention may have a geometry that does not have a center. In that event, “eccentric” simply means that the rib is not located symmetrically about the center of the cover.  
         [0035]     As a result of its positioning, the rib  49  engages the portion of the peripheral edge margin  65  which is located radially opposite from the spout  43  very near the peripheral edge of the diaphragm seal  15 , and so holds the peripheral edge margin tightly closed in these locations. Moving around the peripheral edge margin  65  in either direction from a radially opposite location from the spout  43 , the rib  49  engages the peripheral edge margin progressively farther from the peripheral edge. Near the spout  43 , the rib  49  does not engage the peripheral edge margin  65  at all. Thus, the peripheral edge margin is completely free to flex upwardly near the spout  43  and entirely prevented from flexing radially opposite to the spout. In between, the peripheral edge margin  65  is held with changing amounts of leverage by the rib  49 . The peripheral edge margin  65  may open in locations where the engagement of the rib  49  with the peripheral edge margin occurs at a distance spaced inwardly sufficiently from the edge. By associating the hold down rib  49  with the cover  11 , the diaphragm seal  15  and container  3  can have a completely symmetrical construction. No matter where the spout  43  is angularly located with respect to the central axis A of the container  3 , the diaphragm seal  15  will always be able to open most easily immediately under the spout, and be held from opening at locations radially opposite the spout.  
         [0036]     As liquid is drawn out of the container  3  by the child, the air pressure in the container is gradually reduced. Drawing a vacuum in the container  3  makes it increasingly difficult to keep the diaphragm seal  15  open. To break the vacuum, the bottom wall  69  of the diaphragm seal  15  deflects down as vacuum is detected in the container  3 . More specifically, air pressure acting through the air hole  59  in the retainer  13  pushes the bottom wall  69  of the diaphragm seal  15  down so that the seal with the annular seat  61  on the underside of the retainer is eventually broken. Air can then pass from the air hole  59  in the retainer  13  to the air hole  71  in the center of the bottom wall  69  of the diaphragm seal  15  and thence to the interior of the container  3 . This configuration is illustrated in  FIG. 3 . The air holes  59 ,  71 , retainer base  53  and bottom wall  69  of the diaphragm seal  15  define an air passage for delivering air from outside the container  3  to the interior of the container.  
         [0037]     The operation of the bottom wall  69  of the diaphragm seal  15  to release its seal with the annular seat  61  is entirely independent of the movement of the peripheral edge margin  65  of the diaphragm seal, and can occur periodically when needed to restore a substantially ambient air pressure within the container  3  so that it does not become progressively harder to drawn liquid out of the container. The vertically offset location of the peripheral edge margin  65  from the bottom wall  69  of the diaphragm seal  15  mechanically isolates the two portions so that they can operate as independent valves, and so that movement of either of the peripheral edge margin and the bottom wall does not affect the sealing attachment of the diaphragm seal with the retainer  13 . The offset is provided by the side wall  73  (broadly, “an isolation section”) of the central portion  67  of the diaphragm seal  15 . Similarly, the sealed connection of the retainer mounting flange  55  in the mounting recess  75  of the diaphragm seal  15  does not interfere with movement of peripheral edge margin  65  or movement of the bottom wall  69  around the air hole  71 . It is to be understood that other ways of isolating the peripheral edge margin  65  from the bottom wall  69 , and of isolating these moving parts from the location of connection of the diaphragm seal  15  to the retainer  13  may be used within the scope of the present invention. The location of the flange including the peripheral edge margin  65  at the top of the side wall  73  of the central portion  67  prevents or isolates the peripheral edge margin from significantly reshaping the entire diaphragm seal  15  when flexed so that a good and consistent fit and relative relationship between the diaphragm seal and other parts of the drinking cup  1  (particularly the retainer  13 ) can be maintained.  
         [0038]     Referring now to  FIG. 8 , a second embodiment of the drinking cup  101  comprises a container  103 , a lid assembly  109  including a cover  111  and a retainer  113 , and a diaphragm seal  115 . Parts of the drinking cup  101  of the second embodiment corresponding to those of the drinking cup  1  of the first embodiment will be given the same reference numeral, plus “100”. The cover  111  has a spout  143  defining an opening  145  for liquid to pass through the cover. The cover  111  has a skirt  135  with internal threads  137  capable of mating with external threads  127  located at the upper end of the container  103 . A hold down rib  149  depends from the bottom surface of the cover  111 . As before, the hold down rib  149  extends along a closed curve having a center which is eccentric to the center of the cover  111 .  
         [0039]     In the second embodiment, the retainer  113  is separate from the cover  111  in the final form of the drinking cup  101  purchased by the end user. The retainer  113  is annular in shape and has a lower collar  112 A sealingly received against the inner surface  125  of the container  103  for sealing with the container. An upper collar  112 B of the retainer engages and seals with the cover  111 . The retainer  113  has no fixed connection to the container  103 , and can be removed when the cover  111  is removed. The retainer  113  has a plurality of holes  114  spaced around its circumference ( FIGS. 9 and 9 A) that permit liquid to pass through the retainer. On an upper surface of the retainer  113 , a first annular seat  116  is formed. The circumferentially spaced holes  114  are located radially inwardly of the first annular seat  116 . A second annular seat  161  is formed on the lower surface of the retainer  113 . The retainer has a radially extending air passage  118  that extends between an air hole  159  in the side of the retainer and an air hole  120  in the lower surface of the retainer  113 . The side of the retainer  113  has a circumferential notch  122  so that the air hole  159  on the side of the retainer is not sealed by engagement with the cover  111 . The threaded attachment of the cover  111  to the container  103  is configured in a known way so that air can pass along the threads  137 ,  127  from the exterior of the drinking cup  101  to the air hole  159  in the side of the retainer  113 .  
         [0040]     The diaphragm seal  115  has the shape of a spool in the second embodiment. The diaphragm seal  115  has a central portion (generally indicated at  167 ), an upper flange defining a peripheral edge margin  165 , and a lower flange  166 . The diaphragm seal  115  is received through a center opening  124  of the annular retainer  113  so that the peripheral edge margin  165  of the upper flange overlies the upper surface of the retainer and the lower flange  166  underlies the lower surface of the retainer. The peripheral edge margin  165  of the upper flange makes sealing contact with the first annular seat  116  and the lower flange  166  makes sealing contact with the second annular seat  161 . A side wall  173  of the central portion  167  isolates movement of the peripheral margin  165  of the upper flange from movement of the lower flange  166 . More importantly, the sealed connection of the diaphragm seal  115  with the retainer  113  is isolated from effects of the movements of the peripheral edge margin  165  and lower flange  166 . In addition, the sealed connection of the diaphragm seal  115  with the retainer  113  does not impede movement of peripheral edge margin  165  or lower flange  166 . The diaphragm seal  115  is sealingly connected to the retainer  113  by a circumferential ridge  174  on the side wall  173  that is received in a locking channel  175  in the center aperture  124 .  
         [0041]     The hold down rib  149  engages a top surface of the upper flange  165 . The portions of the upper flange that are radially opposite the spout  143  are engaged nearer to their peripheral edges so that they are firmly held in sealing engagement with the first annular seat  116 . Moving from a radially opposite location to a location directly under the spout  143 , the position of engagement on the upper flange  165  moves gradually radially inward so that a lesser holding force is applied by the rib  149 . When a child sucks on the spout  143 , the vacuum pressure above the peripheral edge margin  165  of the upper flange causes the peripheral edge margin to flex upward. Liquid can now move past the retainer  113  through the holes  114  and to the spout  143  for drinking. As liquid is removed and vacuum pressure increases in the container  103 , the lower flange  166  is deflected off of the second annular seat  161  so that air can pass from the air hole  159 , through the passage  118  and into the container  103  through air hole  120 . The movement of the lower flange  166  is independent of the movement of the upper flange  165 .  
         [0042]     Referring now to  FIGS. 10 and 11 , a third embodiment of a drinking cup  201  constructed according to the principles of the present invention is shown to comprise a container  203 , a lid assembly  209  including a cover  211  and a retainer  213 , and a diaphragm seal  215 . Parts of the drinking cup  201  of the third embodiment corresponding to those of the drinking cup  1  of the first embodiment will be given the same reference numeral, plus “200”. Parts of the drinking cup  203  corresponding to those of the drinking cup  103  of the second embodiment will be given the same reference numeral, plus “100”. The cover  211  has a spout  243  defining an opening  245  for liquid to pass through the cover. The cover  211  has a skirt  235  with internal threads  237  capable of mating with external threads  227  located at the upper end of the container  203 . A hold down rib  249  depends from the bottom surface of the cover  211 . As before, the hold down rib  249  extends along a closed curve having a center which is eccentric to the center of the cover  211 . Air holes  259  located on the cover  211  around a center portion permit air to pass through the cover. An annular seat  261  depends from the underside of the cover  211  radially inward of the air holes  259 . An annular sealing ridge  262  located radially outwardly from the seat  261  seals with the diaphragm seal  215  to block fluid communication of a space radially inward of the ridge from the space between the cover and diaphragm seal located radially outwardly of the ridge. Thus, any liquid from the container  203  located between the bottom of the cover  211  and the diaphragm seal  215  cannot access the air holes  259 .  
         [0043]     In the third embodiment (like the second), the retainer  213  is separate from the cover  211  in the final form of the drinking cup  203  purchased by the end user. The retainer  213  is annular in shape and has a collar  212  sealingly received against the inner surface  225  of the container  203  for sealing with the container. The retainer  213  has no fixed connection to the container  203 , and can be removed when the cover  211  is removed. The retainer  213  has a plurality of holes  214  spaced around its circumference that permit liquid to pass through the retainer ( FIG. 11 ). An annular seat  216  is formed on an upper surface of the retainer  213 . The spaced holes  214  are located radially inwardly of the annular seat  216 . A cover sealing wall  226  projecting from an upper surface of the retainer  213  extends around the perimeter of the retainer and is used to seal the retainer with the cover  211 .  
         [0044]     The diaphragm seal  215  is circular and substantially flat, but has a mounting lip  228  depending from the lower surface of the diaphragm seal received in a center opening  224  of the retainer  213 . The lower end of the mounting lip  228  engages a ledge  224 A of the center opening  224  and provides a reaction surface to the compression applied by the cover  211 . The mounting lip  228  grips the retainer  213  for use in holding the diaphragm seal  215  in position on the retainer. An air hole  271  located in the center of the diaphragm seal  215  is positioned in the middle of the annular seat  261  on the cover  211  so that the diaphragm seal normally seals with the seat and blocks the path between the air holes  259  (only two are shown) in the cover and the center air hole  271  of the diaphragm seal to prevent leakage of liquid out of the drinking cup  201 . The number of air holes  259  may be fewer or greater than two within the scope of the present invention.  
         [0045]     A peripheral edge margin  265  of a flange of the diaphragm seal  215  overlies and sealingly engages the annular seat  216  on the top side of the retainer  213 . Thus, the holes  214  in the retainer  213  are normally blocked by the diaphragm seal  215 . When a child applies a vacuum through the spout  243 , the peripheral edge margin  265  deflects up (except where held down by the hold down rib  249  on the cover  211 ) to uncover the holes  214  in the retainer  213  for permitting liquid in the container  203  to pass through the retainer, past the diaphragm seal  215  and out of the drinking cup  201  through the spout. When the air pressure in the container  203  gets sufficiently low, the central portion  267  of the diaphragm seal  215  (in this embodiment, the portion of the diaphragm seal radially inward of the mounting lip  228 ) is deflected downward around the center air hole  271  so that the diaphragm seal moves off of the annular seat  261  on the bottom of the cover  211 . This allows air to pass from the air holes  259  in the cover  211  to the center air hole  271  in the diaphragm seal and into the container  203  for generally equalizing the pressure in the container with ambient. The diaphragm seal  215 , cover  211 , retainer  213  and container  203  can all be separated from one another for cleaning.  
         [0046]     A fourth embodiment of the drinking cup  301  shown in  FIGS. 12 and 13  is very similar in construction to the drinking cup  1  of the first embodiment. A retainer  313  is fixed to a cover  311  in a center aperture  341 , and may be formed as one piece with the cover. Parts of the drinking cup  301  of the fourth embodiment corresponding to those of the drinking cup  1  of the first embodiment will be given the same reference numeral, plus “300”. A container  303  is substantially identical to the container  3  of the first embodiment. The cover  311  is similar to the cover  11 , but has a hold down rib  349  that is C-shaped rather than annular (see  FIG. 13 ). In regions nearest to a spout  343  of the cover  311 , the rib  349  is completely absent and so can have no effect on the movement of a peripheral edge margin  365  of a diaphragm seal  315 . An annular seat  361  on the underside of the retainer  313  is positioned in the same place as the seat  61  of the first embodiment, but is much taller. The height of the annular seat  361  is necessary because of the somewhat more vertically elongated configuration of a central portion  367  of the diaphragm seal  315  as compared with its counterpart  67  of the first embodiment.  
         [0047]     The vertical elongation of side wall  373  of the central portion  367  of the diaphragm seal  315  further separates a bottom wall  369  of the diaphragm seal from the peripheral edge margin  365 . In this way, the movements of the peripheral edge margin  365  and the bottom wall  369  are even more isolated from one another and from the sealed connection of the diaphragm seal  315  with the retainer  313 . Movement of the peripheral edge margin  365  to open the path from the container  303  to the spout  343  has no effect on the seal of the bottom wall  369  with the annular seat  361  and movement of the bottom wall relative to the seat has no effect on the seal of the peripheral edge margin with the upper edge  331  of the inner rim  321 . Moreover, the diaphragm seal  315  has substantial dimensional stability during the movement of the peripheral edge margin  365  and the bottom wall  369 .  
         [0048]     Another distinction of the diaphragm seal  315  of the fourth embodiment from the diaphragm seal  15  of the first embodiment is that instead of a simple air hole  71  in the center of the diaphragm seal, there is a long air tube  371  extending from the bottom wall  369  of the central portion  367  nearly to the bottom  305  of the container  303 . The tube  371  is formed as one piece with the diaphragm seal  315 , but could be formed as a separate piece. The tube  371  is positioned so that its open bottom end will be clear of liquid in the container  303  so that air passing into the container through the air tube for equalizing pressure with the ambient pressure does not pass through the liquid in the container. In other respects, the drinking cup  303  of the fourth embodiment operates in the same way as the drinking cup  1  of the first embodiment, and will not be further described.  
         [0049]     A drinking cup  401  of the fifth embodiment shown in  FIG. 14  may have the same internal construction as any one of the preceding drinking cups  1 ,  101 ,  201 ,  301 , or a different construction. Parts of the drinking cup  401  of the fifth embodiment corresponding to those of the drinking cup  1  of the first embodiment will be given the same reference numeral, plus “400”. However, the drinking cup  401  of the fifth embodiment has a container  403  that is formed with a locking flange  484  and a stop ring  486  on its outer surface for releasably connecting a handle unit (generally indicated at  488 ) to the drinking cup. The locking flange  484  and stop ring  486  extend continuously around the circumference of the container  403 , but could extend only part way around and/or be formed of multiple spaced apart pieces within the scope of the present invention. The locking flange  484  has a wedge shaped lower surface. The handle unit  488  includes two handles  490  that make the cup easier to hold and move for very small toddlers. It is to be understood that a handle unit (not shown) could include one handle or more than two handles within the scope of the present invention. The handles  490  are connected together by a connecting ring  492  that can be slid over the container  401  from the bottom thereof. A portion of the connecting ring  492  is broken away in FIG.  14  to show the locking flange  484  and stop ring  486  on the container  403 .  
         [0050]     The connecting ring  492  is formed with a nub  494  at each handle  490  having a wedge-shaped upper surface so that when the nub reaches the wedge shaped lower surface of the locking flange  484 , the connecting ring and handles are forced outwardly so that the nub can pass the locking flange. Upon clearing the flange  484 , the natural resiliency of the handle unit  488  causes the handles  490  to snap back toward each other so that the nubs  494  are located against a flat upper surface of the locking flange. The stop ring  486  engages the connecting ring  492  at an upper edge to prevent further upward movement of the handle unit  488  on the container  403 . The handle unit  488  is held on the container  403  between the locking flange  484  and stop ring  486 . Removing the handle unit  488  when not needed can be accomplished by manually deflecting the lower portions of the handles  490  away from each other so that the nubs  494  clear the locking flange  484  and the handle unit can be slid down off of the container  403 .  
         [0051]     When introducing elements of the present invention or the various versions, embodiment(s) or aspects thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., “top”, “bottom”, “side”, etc.) is for convenience of description and does not require any particular orientation of the item described.  
         [0052]     As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.