Abstract:
A drinking cup assembly including a cup having an open end; a cap adapted to enclose the open end, the cap including a drinking spout and an air vent and mating surfaces adjacent or incorporated into the drinking spout and the air vent; and a flow control valve including two stacks adapted to engage the mating surfaces, each of the two stacks having a concave valve face at a top portion thereof.

Description:
This is a continuation, of application Ser. No. 09/019,765 filed Feb. 6, 1998, now U.S. Pat. No. 6,050,445. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to an improved leak-proof cup. More particularly, the present invention relates to a cup assembly having a cap bearing a drinking spout at one side and an air vent spaced from the drinking spout, with a flow control element frictionally engaged in the vicinity of the drinking spout and air vent to allow passage of liquid out and air in during use, while preventing significant leakage through the spout and vent when not in use. 
     BACKGROUND OF THE INVENTION 
     Enclosed cups having drinking spouts and separate air vents, which allow the user to drink from the spout without creating excessive vacuum in the cup, are known in the art. However, drinking spouts and air vents are liable to leak liquid stored in the cup between feedings, or if dropped during use. Accordingly, certain cups have been developed that use valving mechanisms at the spout and at the air vent. These valves respond to suction generated during feeding to open and allow liquid to pass through the spout and to allow air to enter the air vent when a vacuum is developed in the interior of the cup. 
     Two patents disclosing such valves are U.S. Pat. No. 5,079,013 to Belanger and U.S. Pat. No. 5,542,670 to Morano, both commonly assigned or licensed to the assignee of the present application. Applicant hereby incorporates the disclosure of those two patents herein by reference. Applicant has on the market a cup that employs a valve assembly similar to that shown in U.S. Pat. No. 5,079,013 that is secured to sleeves in the underside of the cup&#39;s top, but in which the valves are mounted on a single base element. Applicant is also aware of a competitive product having a flow control element of the configuration depicted in FIG. 1, sold as part of the Tumble Mates Spill Proof Cup by the First Years. 
     Despite the effectiveness of these cup mechanisms, applicant has discovered an improved flow control element and corresponding valve configuration that provides improved fluid flow rates without sacrificing the valve&#39;s resistance to spills or the valve&#39;s durability. 
     SUMMARY OF THE INVENTION 
     Thus, it is an object of the present invention to provide an improved valve mechanism for a cup assembly that is substantially leak-proof even when upended, dropped or shaken. 
     It is a further object of the present invention to provide an improved valve mechanism for a leak-proof cup that gives higher fluid flow rates at normal suction forces without sacrificing durability or resistance to spills. 
     It is a further object of the present invention to provide an improved valve mechanism, cap and cup that are easy to clean and easy to assemble. 
     Accordingly, the present invention provides a drinking cup assembly including a cup having an open end; a cap adapted to enclose the open end, the cap including a drinking spout and an air vent and mating surfaces adjacent or incorporated into the drinking spout and the air vent; and a flow control valve including two stacks adapted to engage the mating surfaces, each of the two stacks having a concave valve face at a top portion thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a prior art valve mechanism; 
     FIG. 2 is a perspective view of a cup, cap and valve assembly according to the present invention; 
     FIG. 3 is a section diagram taken along the lines  3 — 3 ′ in FIG. 2; 
     FIG. 4 is a side view of the valve of FIG. 3; and 
     FIG. 5 is a top view of the valve of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the figures and, in particular, FIGS. 2 through 4, the cup, cap and valve assembly of the present invention is generally referred to by reference numeral  10  The assembly  10  includes a cup  12 , a cap  14  and a flow control valve  20 . Cap  14  is adapted to seal cup  12 , with the exception of the apertures in the spout  16  and air vent  18  formed in its surface. Flow control valve  20  is adapted to communicate with spout  16  and air vent  18 , to form the substantially spill-proof assembly  10 . 
     Cap  14  is formed with mating surfaces, preferably adjacent to or incorporated into spout  16  and air vent  18 , to frictionally engage flow control valve  20  and place the flow control valve in fluid communication with spout  16  and air vent  18 . In the embodiment depicted in FIG. 2, cap  14  is formed with cylindrical recesses  17  within spout  16  and below air vent  18 . These recesses  17  are configured to accept flow control valve  20 . 
     In the embodiment shown in FIGS. 3 through 5, flow control valve  20  includes two stacks  24 . Stacks  24  include lower portions  26 , upper portions  28  and valve faces  30  bearing slits  32 . These stacks  24  are adapted to be pressed into recesses  17  to friction fit flow control valve  20  into cap  14 . Accordingly, when recesses  17  have a lower cylindrical portion, as preferred, lower portions  26  of stacks  24  are also preferably substantially cylindrical in shape. 
     As also shown in FIGS. 3 and 4, each stack  24  is elongated. In addition, each stack  24  is of significant diameter and of substantially equal height. The elongated shape of stacks  24  enables them to place valve faces  30  and slits  32  (see FIG. 5) in close proximity to the apertures in spout  16  and air vent  18 . The diameter of stacks  24  permits significant, relatively unconstrained fluid flow to the area of slits  32 . It has been found that this arrangement provides optimal balancing of suction needed to open slits  32  and the fluid flow through the slits. Similarly, its substantial cylindrical diameter and resulting inner contour presents a simple, wide opening and tube to enable thorough cleaning of the stacks  24  after use and to minimize the number of corners and niches in which dried or congealed liquid can be deposited. It is preferred that the outer contour of stacks  24  be stepped, as shown in FIGS. 3 and 4, but that the inner contour of the stacks be a constant diameter or of constantly diminishing diameter, thus presenting a smooth, unstepped inner face. Thus, the smooth inner face is preferably either cylindrical, frustoconical, or a combination of the two. This smooth inner face further enhances free fluid flow and promotes easy cleaning of stacks  24 . The fact that this preferred flow control valve  20  is easy to clean is very important both to the proper and sanitary functioning of the assembly  10 , and also to consumer acceptance of the valve. 
     It has also been discovered that the preferred concave shape of valve faces  30 , in conjunction with the attendant curved shape of slits  32 , provides superior fluid flow rate through slits  32  than existing valve configurations. This makes the assembly  10  easier to drink from and less frustrating and tiring to use. Furthermore, it has been found that elongated single slits  32  are preferred to cross-cuts or other types of apertures through valve faces  30  It is also preferred that slits  32  extend substantially from edge to edge of concave valve faces  30 . 
     Most preferably, the radius of curvature of the valve face  30  that is aligned with spout  16  is about 0.267 inches. The most preferred radius of curvature of the valve face  30  that is aligned with air vent  18  is also about 0.267 inches. The most preferred length of slit  32  that is aligned with spout  16  is about 0.235 inches. The most preferred length of slit  32  that is aligned with air vent  18  is about 0.170 inches. The most preferred inner diameter of the stack  24  that is aligned with spout  16  is from about 0.301 inches to about 0.368 inches, ideally a frustoconical shape having the foregoing as minimum and maximum diameters. The most preferred inner diameter of the stack  24  that is aligned with air vent  18  is from about 0.252 inches to about 0.368 inches, ideally a frustoconical shape having the foregoing as minimum and maximum diameters. The most preferred height of the stack  24  that is aligned with spout  16  is about 0.803 inches from top to bottom, and about 0.521 inches from indentation to bottom. The most preferred height of the stack  24  that is aligned with air vent  18  is about 0.730 from top to bottom, and about 0.550 from indentation to bottom. The two stacks  24  are preferably 1.60 inches on center. The preferred outer diameter of the lower portion  26  of the stack  24  that is aligned with spout  16  is about 0.522 inches. The preferred outer diameter of the lower portion  26  of the stack  24  that is aligned with air vent  18  is about 0.457 inches. These dimensions provide an interference fit with a cup lid having cylindrical recesses  17  having preferred inner diameters of about 0.499 inches and about 0.439 inches, respectively. All of the foregoing measurements are subject to a preferred tolerance of plus or minus about 0.005 inches. In addition, a further dimension that is most preferred is the thickness of valve face  30 . It is most preferably about 0.023 inches thick, with a preferred tolerance of only about plus or minus 0.002 inches. This dimension has been found to be very important in providing proper flexion of the valve faces  30  and opening of slits  32  under suction during use. 
     It is preferred that the flow control valve  20  be formed from a single piece of elastomeric material to facilitate easy insertion into and removal from recesses  17 . However, flow control valve  20  can be formed of two separate valving elements, each adapted to be inserted into recesses  17  or otherwise engage cap  14 . The elastomeric material used is most preferably silicone, but TPE (thermoplastic elastomer), natural rubber, and synthetic rubber (e.g., isoprene) are also preferred. 
     The following data demonstrate the improved flow rates of a flow control valve  20  according to the present invention. Six samples of a flow control valve as depicted in FIG. 3 (Valve A) were tested against six samples of a flow control valve as depicted in FIG. 1 (Valve B) and against ten samples of a flow control valve as disclosed in U.S. Pat. No. 5,079,013 to Belanger (Valve C). 
     
       
         
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Suction to 
                 Suction for 
                   
               
               
                   
                 Sample 
                 Start Flow 
                 Continuous 
                 Time to Evacuate 
               
               
                   
                 Number 
                 (psi) 
                 Flow (psi) 
                 100 ml water (sec.) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Valve A 
               
             
          
           
               
                   
                 1 
                 1.23 
                 2.21 
                 49 
               
               
                   
                 2 
                 1.47 
                 2.21 
                 37 
               
               
                   
                 3 
                 1.47 
                 2.46 
                 51 
               
               
                   
                 4 
                 1.47 
                 2.33 
                 44 
               
               
                   
                 5 
                 1.23 
                 2.33 
                 56 
               
               
                   
                 6 
                 1.23 
                 2.21 
                 50 
               
               
                   
                 Avg. 
                 1.35 
                 2.29 
                 48 
               
             
          
           
               
                 Valve B 
               
             
          
           
               
                   
                 1 
                 0.98 
                 2.82 
                 58 
               
               
                   
                 2 
                 0.98 
                 2.95 
                 41 
               
               
                   
                 3 
                 1.72 
                 2.46 
                 44 
               
               
                   
                 4 
                 1.72 
                 2.70 
                 57 
               
               
                   
                 5 
                 1.47 
                 2.70 
                 63 
               
               
                   
                 6 
                 1.23 
                 2.46 
                 75 
               
               
                   
                 Avg. 
                 1.35 
                 2.68 
                 56 
               
             
          
           
               
                 Valve C 
               
             
          
           
               
                 1 
                 2.46 
                 4.42 
                 36 
               
               
                 2 
                 2.95 
                 4.54 
                 27 
               
               
                 3 
                 2.95 
                 4.42 
                 76 
               
               
                 4 
                 2.46 
                 3.93 
                 24 
               
               
                 5 
                 2.95 
                 4.42 
                 38 
               
               
                 6 
                 3.19 
                 4.17 
                 33 
               
               
                 7 
                 2.46 
                 3.93 
                 78 
               
               
                 8 
                 3.19 
                 4.42 
                 29 
               
               
                 9 
                 2.46 
                 3.93 
                 40 
               
               
                 10 
                 2.95 
                 3.93 
                 26 
               
               
                 Avg. 
                 2.80 
                 4.21 
                 40.7 
               
               
                   
               
             
          
         
       
     
     These data show that the Valve A, a valve according to the present invention, requires lower suction to generate a continuous flow than the prior art valves, and requires less time to evacuate 100 ml of water than the prior art elastomeric valve, Valve B. Moreover, this Valve A is more consistent from sample to sample than the controls. This provides a more acceptable product. 
     Various modifications may be made to the foregoing disclosure as will be apparent to those skilled in the art. Thus, it will be obvious to one of ordinary skill in the art that the foregoing description and drawings are merely illustrative of certain preferred embodiments of the present invention, and that various obvious modifications can be made to these embodiments in accordance with the spirit and scope of the appended claims.