Patent Publication Number: US-2012043293-A1

Title: Nipple For An Infant Bottle Assembly And An Infant Bottle Assembly Having Such a Nipple

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to patent application Ser. No. 13/112,162 filed May 20, 2011, which claims the priority of Provisional Patent Application Ser. No. 61/347,151 entitled “NIPPLE FOR AN INFANT BOTTLE ASSEMBLY HAVING A FLOW CONTROL VALVE AND AN INFANT BOTTLE ASSEMBLY HAVING SUCH A NIPPLE”, filed May 21, 2010, both of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     The field of this invention relates generally to bottle assemblies and more particularly to a nipple for a bottle assembly having a flow control valve. 
     Bottle assemblies, such as infant bottle assemblies, typically have multiple components including a bottle, a nipple, a collar for securing the nipple to the bottle, and a cap for covering the nipple when the bottle is not in use. The nipple typically has one or more openings for allowing liquid contained within the bottle to exit through the nipple and into an infant&#39;s mouth for consumption by the infant (or young child). During use, the infant places an end of the nipple in their mouth and sucks on the nipple to withdraw the liquid contained within the bottle. 
     In conventional infant bottle assemblies, the flow of liquid through the nipple is often controlled by the size and/or number of openings formed in the end of the nipple. To change the flow rate of most bottle assemblies, the entire nipple has to be replaced with a different nipple having the desired flow rate. Often, manufacturers of bottle assemblies will provide a series of nipples with different sizes and/or number of openings that are suitable for use with their bottles. For example, it is common for manufacturers to provide nipples having three different flow rates for use with their bottle assemblies. Often, a first low-flow nipple is provided wherein the nipple has a single, relatively small opening therein for allowing only a low flow of liquid to pass through. Low-flow nipples are typically designed for use by infants less than 3 months of age. A second medium-flow nipple may be provided wherein the nipple has two or more openings and/or the opening(s) in the nipple are larger than those in the low-flow nipple. Medium-flow nipples are typically designed for use by infants between 3 months and 6 months of age. A third high-flow nipple may be provided wherein the nipple has a plurality of openings and/or the opening(s) in the nipple are larger than those in the medium-flow nipple. High-flow nipples are typically designed for use by infants over 6 months of age. 
     One issue that has not been addressed with these variable flow nipples is the issue of over-feeding. Recent research reports indicate that infants using bottles are consistently over-fed and at higher risk for early childhood obesity. Bottle-fed infants have significantly higher caloric intake than infants fed at the breast. See, e.g., Ziegler E E.,  Growth of breast-fed and formula - fed infants , Nestle Nutr Workshop Ser Pediatr Program 2006; 58:51-59; Li R, Fein S B, Grumm-Strawn L M.,  Association of breastfeeding intensity and bottle - emptying behaviors at early infancy with infant&#39;s risk for excess weight at late infancy , Pediatrics 2008; 122 (Suppl 2):577-584; and Noble S, Emmett P.,  Differences in weaning practice, food and nutrient intake between breast - and formula-fed  4- month - old infants in England , J Hum Nutr Diet 2006; 19(4):303-13. The difference in energy intake results in increased adiposity in bottle-fed infants. See, e.g., Bonuck K A, Huang V, Fletcher J.,  Inappropriate bottle use: an early risk for overweight? Literature review and pilot data for a bottle - weaning trial , Matern Child Nutr 2010; 6(1):38-52 and Koletzko B, von Kries R, Closa R, Escribano J, Scaglioni S, Giovannini M, Beyer J, Demmelmair H, Anton B, Grusfeld D, Dobrazanska A, Sengier A, Langhedries J P, Rolland Cachera M F, Grote V.,  Can infant feeding choices modulate later obesity risk ?, Am J Clin Nutr 2009; 89(5):15025-15085. A change in bottle technology is needed to help reduce the risk of obesity. 
     Prior art nipples, however, fail to adequately mimic how an infant would nurse on a mother&#39;s breast. In other words, bottle feeding an infant using conventional infant bottle assemblies fails to adequately mimic breast feeding the infant. When an infant is placed at the mother&#39;s breast to feed, a cascade of events occurs. For one, the infant places their mouth and tongue (latches) with a negative pressure of approximately 30 mm Hg (latching pressure) to the nipple/areola and stimulates milk ejection through a series of quick, shallow sucks referred to as non-nutritive suckling. Non-nutritive suckling consists of stable lengths of sucking bursts and duration of pauses. The average pressure of non-nutritive suckling is approximately 70 to 90 millimeters of mercury (mm Hg) to induce milk ejection from the breast. 
     When milk ejection begins, the infant collects the milk using strong, relatively even draws, which is known in the art as nutritive suckling. During nutritive suckling the movement of the infant&#39;s tongue, jaw, and swallowing facilitates milk flow. The average vacuum pressure applied to the breast during one of the draws is approximately 75-100 mm Hg. The infant will pause between draws to swallow. However, the infant will maintain a latching pressure of about 30 mm Hg while swallowing the collected milk. Thus, the vacuum pressure applied to the breast by the infant fluctuates between the drawing pressure (between about 75-100 mm Hg) and the latching pressure (about 30 mm Hg). As a result, at least some vacuum pressure is applied to the breast by the infant throughout the duration of the nutritive suckling. 
     However, the vacuum pressure needed to extract liquid from a conventional nipple is substantially lower than that needed to express milk from the breast of a mother. In fact, many nipples allow liquid to exit the bottle via gravity. In addition, these low pressure actuated nipples are susceptible to leaking. 
     Moreover, many nipples are shaped inappropriately for allowing the infant to use their mouth, tongue and palate in same manner as they would when they are breast feeding. That is, most conventional nipples are inadequately shaped for allowing the infant to latch onto the nipple. The shape of the mother&#39;s breast, on the other hand, promotes the proper placement and movement of the infant&#39;s mouth when the infant is latched onto the breast. 
     There is a need, therefore, for a nipple for use with an infant bottle assembly to better simulate the breast of a nursing mother, more effectively facilitates similar oral pressures and movements that occur during feeding from a breast, reduces the potential of leakage, and reduces the potential for over-feeding. 
     BRIEF DESCRIPTION 
     In one aspect, a nipple for use with a nursing bottle is provided. The nipple includes a base portion and a bulbous sidewall connected to and extending upward from the base portion. The bulbous sidewall has a height and a maximum width that is larger than said height. The nipple further includes an end portion extending upward from the bulbous sidewall and having an outlet opening therein. 
     In another aspect, a nipple for use with a nursing bottle is provided. The nipple includes a base portion positionable proximate the nursing bottle upon assembly therewith, and a bulbous sidewall connected to and extending upward from the base portion. The bulbous sidewall has a height and a maximum width that is larger than said height. The nipple further includes a generally cylindrical end portion extending upward from the bulbous sidewall distal from the base portion and having an outlet opening therein. 
     In yet another aspect, a nipple for use with a nursing bottle is provided. The nipple includes a base portion positionable proximate the bottle, a bulbous sidewall extending upward from the base portion and having a first height and a maximum width that is larger than the first height, and an end portion extending upward from the bulbous sidewall distal from said base portion and having a second height. The second height is less than the first height. The end portion of the nipple has an outlet opening. 
     In still another aspect, a nursing bottle assembly is provided. The nursing bottle assembly includes a bottle having a closed bottom, an open top, and a sidewall extending between the bottom and the open top. The bottom and sidewall together define an interior chamber for holding liquid. The nursing bottle assembly further includes a nipple configurable for assembly with the bottle and having an outlet opening through which liquid exits the bottle assembly during use. The nipple includes a base portion configured to interface with the top of the bottle and being open to receive liquid from the interior chamber into the nipple during use of the bottle assembly and a bulbous sidewall connected to and extending upward from the base portion. The bulbous sidewall has a height and a maximum width that is larger than the height. The nipple further includes an end portion extending upward from the bulbous sidewall and having an opening therein defining the nipple outlet opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective of one embodiment of a bottle assembly having a nipple with a flow control valve; 
         FIG. 2  is an exploded perspective of the bottle assembly; 
         FIG. 3  is a side elevation of a bottle of the bottle assembly; 
         FIG. 4  is a top plan view of the bottle; 
         FIG. 5  is a bottom plan view of the bottle; 
         FIG. 6  is a side elevation of a cover of the bottle assembly; 
         FIG. 7  is a top plan view of the cover; 
         FIG. 8  is a bottom plan view of the cover; 
         FIG. 9  is a perspective of a nipple of the bottle assembly; 
         FIG. 10  is a side elevation of the nipple; 
         FIG. 11  is a top plan view of the nipple; 
         FIG. 12  is a bottom plan view of the nipple; 
         FIG. 13  is a perspective of a flow control valve of the bottle assembly; 
         FIG. 14  is a side elevation of a collar of the bottle assembly; 
         FIG. 15  is a top plan view of the collar; 
         FIG. 16  is a bottom plan view of the collar; 
         FIG. 17  is a perspective of a bottom closure member of the bottle assembly; 
         FIG. 18  is a side elevation of the bottom closure member; 
         FIG. 19  is a top plan view of the bottom closure member; 
         FIG. 20  is a bottom plan view of the bottom closure member; 
         FIG. 21  is a top plan view of a diaphragm of the bottle assembly; 
         FIG. 22  is a side elevation of the diaphragm; 
         FIG. 23  is a cross-section taken along line  23 - 23  of  FIG. 21 ; 
         FIG. 24  is a fragmentary perspective of the bottle assembly with portions broken away to show the diaphragm in a sealed position with respect to the bottom closure member; 
         FIG. 25  is vertical cross-section of the bottle assembly showing the diaphragm in the sealed position with respect to the bottom closure member; 
         FIG. 26  is a fragmentary perspective of the bottle assembly with portions broken away to show a liquid therein and the diaphragm in an unsealed position with respect to the bottom closure member, the bottle assembly being shown tilted to a drinking position by an infant; 
         FIG. 27  is a longitudinal cross section of the bottle assembly having the liquid therein and the diaphragm returned to its sealed position with respect to the bottom closure member, the bottle assembly being shown in its tilted, drinking position; 
         FIG. 28  is an enlarged view taken from  FIG. 26  illustrating a fluid control valve disposed within a nipple of the bottle assembly, the fluid control valve being in a closed position; and 
         FIG. 29  is an enlarged view similar to  FIG. 27  but illustrating the fluid control valve in an open position. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings and in particular to  FIGS. 1 and 2 , a bottle assembly having a nipple with a flow control valve therein is indicated generally at  1 . The bottle assembly  1  comprises a bottle  3 , a cover  9 , a nipple  11 , and a collar  13 . Each of the bottle, cover, nipple, and collar are indicated generally by their respective reference number. As illustrated in  FIGS. 2-5 , the bottle  3  has an open bottom  5 , an open top  7 , and a generally cylindrical side wall  6  extending between the open bottom and the open top. The cylindrical side wall  6  includes a base portion  8 , a top portion  10 , and a middle portion  12  extending between the base and top portions. 
     With reference still to  FIGS. 2-5 , the base portion  8  of the side wall  6  of the bottle  3  is generally cylindrical and includes a circular lower edge  20 , an annular rib  23  spaced about the lower edge, and external threads  25  disposed between the lower edge and the annular rib. The annular rib  23  has a generally flat lower surface  23   a  and a sloped upper surface  23   b . The top portion  10  of the side wall  6  is generally cylindrical and has a circular upper edge  21  and external threads  27  spaced below the upper edge. In the illustrated embodiment, the top portion  10  of the bottle  3  has a diameter that is less than the diameters of the middle portion  12  and the base portion  8 . As a result of the difference in their diameters, the middle portion  12  has a region that tapers toward the top portion  10 . It is understood, however, that the diameters of the top, middle, and base portions  10 ,  12 ,  8  can be substantially the same. It is also understood that the middle portion  12  of the bottle  3  could have a diameter less than the top and base portions  10 ,  8 , which would facilitate grasping of the bottle  3  by the user (i.e., infant, young child, caregiver). 
     The illustrated bottle  3  has a liquid chamber  28  adapted to hold a quantity of liquid for consumption by an infant or a young child. More specifically, the illustrated bottle  3  is adapted for use by an infant and to hold approximately 6 ounces of liquid (e.g., milk, breast milk, formula, water, juice). The bottle  3  can be made of any suitable material (e.g., plastic, glass, stainless steel, aluminum) and can be made in any desired color or colors, and may be transparent, translucent, or opaque. In one suitable embodiment, the bottle  3  is made from plastic and manufactured using an injection mold process, which provides greater control over the thickness of the bottle as compared to a blown mold process. It is understood that the bottle  3  can have different configurations than those illustrated herein (e.g., a sports bottle, a travel cup, a training or sippy cup) and sized to hold quantities of liquid besides 6 ounces (e.g., 2 ounces, 4 ounces, 9 ounces, 12 ounces, etc.). 
     The cover  9 , which is illustrated in  FIGS. 6-8 , is removeably securable to the collar  13  ( FIGS. 1 and 2 ) via a snap-fit connection but it is understood that other types of suitable connections can be used (e.g., a threaded connection). As best seen in  FIGS. 2 and 6 , the cover  9  has a lower cylindrical portion  31 , a domed upper portion  33 , and a sloped intermediate or transition portion  35  that extends between the lower portion and the upper portion. In the illustrated embodiment, the lower portion  31  has three inward extending tabs  37  adapted for releasable snap-fit connection with the collar  13 . The three tabs  37  can be seen in  FIG. 8 . As a result, the cover  9  can be selectively secured to the collar  13  during periods of non-use (e.g., storage, travel) to cover the nipple  11  ( FIGS. 1 and 2 ) and removed during periods of use for providing access to the nipple. The cover  9  can be made of any suitable material, such as polypropylene, and can be made in any desired color or colors, and may be transparent (as illustrated), translucent, or opaque. It is contemplated that the cover  9  can be omitted from the bottle assembly  1 . It is understood that the cover  9  can have more or fewer tabs  37  than the three seen in the illustrated embodiment. 
     With reference to FIGS.  2  and  9 - 12 , the nipple  11  includes a base portion  39  and a nipple portion  41  that extends up from the base portion. The base portion  39  comprises an annular flange having a generally circular outer edge  43  and a generally circular inner edge  45 . In the illustrated embodiment, a continuous, peripheral lip  47  projects up from the flange generally adjacent the circular outer edge  43  of the base portion  39 . It is understood that the peripheral lip  47  can be discontinuous (i.e., formed from two or more discrete segments) or even omitted from the base portion  39 . 
     The nipple portion  41  of the nipple  11  extends up from the base portion  39  generally adjacent the circular inner edge  45  thereof As seen in  FIG. 10 , the nipple portion  41  includes a generally bulbous sidewall  49  and a generally cylindrical end  51  extending upward from the bulbous sidewall. The cylindrical end  51  has an opening  53  therein. In the illustrated embodiment, the bulbous sidewall  49  has an upper tapered portion  49   a  that is slightly convex and has a radius R 1  of about 35 mm. It is understood, however, that the upper tapered portion  49   a  can have any suitable radius R 1  without departing from the scope of this invention. 
     As seen in  FIG. 10 , the bulbous sidewall  49  has a height H and a width W (i.e., diameter) at its widest part that is substantially greater than its height. In the illustrated embodiment, for example, the width W of the bulbous sidewall  49  is approximately twice that of the height H of the sidewall. More specifically, the height H of the bulbous sidewall  49  of the nipple  11  is about 21 mm and the widest part of the sidewall has a width W of about 42 mm. As a result, the upper tapered portion  49   a  of the bulbous sidewall  49  tapers from the cylindrical end  51  downward toward the widest portion of the sidewall, and a lower tapered portion  49   b  that tapers from the widest portion of the sidewall inward to proximate the base portion  39 . It is contemplated that the widest part of the bulbous sidewall  49  may have any suitable width and height without departing from the scope of this invention. 
     The cylindrical end  51  of the nipple  11  has a height H′ such that a diameter-to-height ratio of the cylindrical end is between about 1.15 and about 1.6. For example, the diameter D and the height H′ of the cylindrical end are about 13-16 mm and about 10 mm, respectively. It is contemplated that the cylindrical end  51  can have any suitable diameter and height (i.e., diameter-to-height ratio) without departing from the scope of this invention. The illustrated cylindrical end  51  has one generally circular opening  53  therein but it is understood that more openings can be provided in the bulbous end and that the openings can have one or more different shapes (e.g., square, triangle, oval, slits) without departing from the scope of this invention. As seen in  FIG. 10 , the cylindrical end  51  of the nipple  11  includes an interior annular recess  52  suitably sized for capturing a flow control valve as explained in more detail below. 
     The nipple  11  of the illustrated embodiment is configured to generally resemble a human female&#39;s breast. More specifically, the cylindrical end  51  is configured to resemble the nipple of a human breast and the bulbous sidewall  49  is configured to resemble the portions of the human breast surrounding the nipple (e.g., areola, skin). As a result, the infant using the disclosed nipple  11  is able to latch onto the nipple as he/she would their mother&#39;s breast. It is contemplated, however, that the nipple  11  can have different shapes and sizes than those illustrated and described herein without departing from some aspects of this invention. 
     In one suitable embodiment, the nipple  11  is fabricated from a substantially pliable material such as at least one of a rubber material, a silicone material, and a latex material. It is contemplated, however, that the nipple  11  may be fabricated from any suitable material without departing from the scope of this invention. The illustrated nipple  11  is suitably transparent or translucent but it is understood that the nipple may instead be opaque. 
     A suitable flow control valve, such as the flow control valve  68  illustrated in  FIG. 13 , is disposed in the nipple  11  for regulating the flow of liquid from the liquid chamber  28  of the bottle  3 , through the nipple  11  and out the opening  53  in the nipple. In the illustrated embodiment, the flow control valve  68  is captured by the annular recess  52  in the cylindrical end  51  of the nipple  11  and spaced from the opening  53  in the nipple  11 . In this embodiment, the flow control valve  68  is formed separately from the nipple  11 , inserted into the annular recess  52 , and bonded thereto. It is understood, however, that the flow control valve  68  can be formed (e.g., molded) integrally with the nipple  11 . One suitable flow control valve  68  is the SureFlo® elastomeric valve available from Liquid Molding Systems, Inc. (LMS) of Midland, Mich., U.S.A. 
     In one embodiment, the flow control valve  68  is configured to open when a predetermined external vacuum pressure is applied to the valve by the user via sucking (broadly, “opening pressure”) is in a range between about 30 mm Hg and about 100 mm Hg. In one suitable embodiment, the valve  68  is configured to open when the vacuum pressure applied to the valve is approximately 50 mm Hg. The flow control valve  68  is also configured to close when the vacuum pressure applied to the valve by the user via sucking (broadly, “closing pressure”) falls to or slightly below the opening pressure (e.g., approximately 50 mm Hg in the illustrated embodiment). It is contemplated, however, that the flow control valve  68  can be configured to open and close at any suitable vacuum pressures besides those disclosed herein. As a result of the significant external vacuum pressure needed to open the flow control valve  68  and thereby allow liquid to flow therethrough, the flow control valve substantially reduces the potential for leakage through the nipple  11 . 
     The nipple  11  having the disclosed flow control valve  68  better simulates how milk is drawn from a female&#39;s breast. During nutritive suckling, an infant collects milk being ejected using strong, even draws followed by a brief pause for swallowing. Thus, the infant cyclically sucks to draw milk into his/her mouth and pauses to swallow the collected milk. The flow of milk from the human breast is not continuous but instead flows when the infant applies sufficient vacuum in combination with proper mouth movements. Moreover and as discussed above, the shape of the female nipple and portions of the breast surrounding the nipple promotes proper placement, latching and movement of the infant&#39;s mouth. 
     Thus, the nipple  11  disclosed herein is configured to better simulate a breast feeding event. In the illustrated embodiment, the flow control valve  68  is configured to open and close when the vacuum pressure applied to the nipple by the infant is approximately 50 mm Hg. As a result, as long as the infant applies a vacuum pressure above 50 mm Hg, liquid will flow through the nipple and into the infant&#39;s mouth for consumption. If the vacuum pressure applied by the infant to the nipple via sucking falls to or slightly below 50 mm Hg, the liquid will stop flowing through the flow control valve  68 . In one suitable embodiment, the flow control valve  68  is configured for allowing a flow rate of about 7 milliliters per minute (ml/min) to about 15 ml/min based on the assumption that the infant cycles between draws and pauses about 60 times per minute. It is contemplated that the flow control valve  68  can be configured to operate at any suitable opening or closing pressure and at any suitable flow rate. 
     Accordingly, the present nipple  11  having the combination of its breast-like shape and the flow control valve  68  therein better simulates the feeding of an infant from a breast of a nursing mother and more effectively allows the infant to use oral pressures and movements that are similar to those used during feeding from a breast as compared to prior art nipples. 
     The flow control valve  68  is also adapted to open when the liquid chamber of the bottle is subjected to a predetermined internal vacuum pressure. In the illustrated embodiment, for example, the flow control valve  68  will open when the vacuum pressure within the liquid chamber reaches or exceeds approximately 10 mm Hg and allow ambient air to flow into the liquid chamber. 
     Referring now to  FIGS. 14-16 , the collar  13  includes a generally flat upper portion  55  and a cylindrical skirt  57  depending downward from the upper portion. The upper portion  55  includes a generally circular opening  59  therein for allowing the nipple portion  41  of the nipple  11  to pass through the collar  13  as illustrated in  FIG. 1 . As seen in  FIG. 16 , the skirt  57  includes internal threads  61  that are adapted for mating with the external threads  27  ( FIG. 2 ) of the top portion  10  of the bottle  3  for selectively securing the collar  13  and the nipple  11  to the bottle assembly  1 . With reference to  FIG. 14 , the collar  13  also includes an external channel  63  sized for receiving the tabs  37  of the cover  9  when the cover is secured thereto. The tabs  37  of the cover  9  and the channel  63  of the collar  13  collectively define the snap-fit connection therebetween. 
     In the illustrated embodiment, the nipple  11  and the collar  13  collectively define a top closure member, indicated generally at  64 , for closing the open top  7  of the bottle  3  ( FIG. 2 ). It is contemplated, however, that the top closure member  64  can have a different configuration than that illustrated herein. For example, the top closure member  64  can have any configuration suitable for used with, e.g., a nursing bottle, a sports bottle, a travel cup, a training cup, and/or a sippy cup. 
     Referring briefly back to  FIGS. 1 and 2 , the bottle assembly  1  further comprises a bottom closure member  65  for closing the open bottom  5  of the bottle  3 . As seen in  FIGS. 17-20 , the bottom closure member  65  includes a generally cup-shaped socket, indicated generally at  67 , and a tapered foot  69  extending downward and outward from the socket. The tapered foot  69  provides a stable base for the bottle assembly  1  when the bottle assembly is placed on a generally flat surface (e.g., a counter top, a table) to thereby inhibit tipping of the bottle assembly. 
     The cup-shaped socket  67  includes a cylindrical wall  71  and a base panel  73  closing a bottom end of the cylindrical wall. The cylindrical wall  71  has internal threads  75  for mating with the external threads  25  ( FIG. 2 ) on the base portion  8  of the bottle  3 . Accordingly and as explained in more detail below, the bottom closure member  65  can be selectively coupled to and selectively decoupled from the bottle  3  via the threaded connection therebetween. As seen in  FIG. 19 , the base panel  73  has a centrally located circular seat  77 , two circular apertures  79  located adjacent the seat, and an annular shoulder  81 . While the seat  77  in the illustrated embodiment is circular, it is understood that the seat can have other shapes (e.g., square, hexagonal). It is also understood that, in some suitable embodiments, the seat  77  can be omitted. It is further understood that the apertures  79  can have shapes other than circular and that more or fewer apertures can be located in the base panel  73 . The annular shoulder  81  is disposed on an upper surface of the base panel  73  at a location generally adjacent to and transversely inward from the cylindrical wall  71 . In the illustrated embodiment, the base panel  73  is generally flat but it is understood that the base panel could have other suitable shapes (e.g., conical, frustum, domed). It is also understood that the base panel  73  can include suitable reinforcing members (e.g., ribs). 
     With reference now to  FIGS. 21-24  (and in particular to  FIG. 24 ), the bottle assembly  1  further comprises a diaphragm (broadly, a “vent member”), indicated generally at  83 , disposed between the lower edge  20  of the bottle  3  and the bottom closure member  65 . The diaphragm  83  closes the open bottom  5  ( FIG. 2 ) of the bottle  3 . The diaphragm  83  has a roughly disk-shaped portion  85 , an annular rim  87  circumscribing the disk-shaped portion, and a central seating member, indicated generally at  89 . The central seating member  89  comprises first and second sealing elements  91 ,  93  that project outward from the disk-shaped portion  85 , and a central air passage  95  that extends axially through the diaphragm  83 . As seen in  FIG. 22 , each of the first and second sealing elements  91 ,  93  of the diaphragm  83  are generally frustum and coaxially aligned with the air passage  95  and each other. As a result, the air passage  95  extends through each of the first and second sealing elements  91 ,  93 . The diaphragm  83  is symmetric in that it has a first side  97  and a substantially identical second side  99  ( FIG. 23 ). As a result, the diaphragm  83  is positionable in the bottom closure member  65  with either side  97 ,  99  facing up. 
     As illustrated in  FIGS. 24 and 25 , the diaphragm  83  is captured between the bottom closure member  65  and the base portion  8  of the bottle  3 . More specifically, the diaphragm  83  is inserted into the cup-shaped socket  67  ( FIG. 17 ) of the bottom closure member so that one of the first and second sealing elements  91 ,  93  rest on the seat  77  of the base panel  73  of the bottom closure member  65  and the annular rim  87  of the diaphragm is disposed adjacent a lower portion of the cylindrical wall  71  outward of the annular shoulder  81  of the bottom closure member. The bottom closure member  65  is screwed onto the bottle  3  via the interior threads  75  of the bottom closure member and the external threads  25  of the base portion  8  on the bottle. In doing so, the lower edge  20  of the bottle  3  engages a portion of the diaphragm  83  at a location generally opposed to the annular shoulder  81  of the bottom closure member to thereby pinch the diaphragm between the bottle and the bottom closure member to form a liquid tight seal. As seen in  FIG. 25 , an air gap  101  is formed between the diaphragm  83  and the base panel  73  of the bottom closure member  65 . Moreover, the diaphragm  83  is slightly bowed upward at its center when it is captured between the bottom closure member  65  and the bottle  3 . This causes the diaphragm, which is resilient, to be biased toward the base panel  73  of the bottom closure member  65 . More specifically, bowing the diaphragm  83  upward at its center causes one of the first and second sealing elements  91 ,  93  to be biased against the seat  77  of the base panel  73  of the bottom closure member  65 . 
     The bottle assembly  1  can be repeatedly taken apart for thorough cleaning ( FIG. 2 ) and reassembled for the next use ( FIG. 1 ). The separable components of the bottle assembly  1  are all relatively large so that they are easy to handle, are not easily lost, and pose a reduced risk of danger to small children. In addition, the number of separable components is minimized to make assembly and reassembly of the bottle assembly  1  relatively easy. 
     As mentioned above, the cover  9  can be selectively removed from the bottle assembly  1  via its snap-fit connection with the collar  13 . Thus, a user of the bottle assembly can remove the cover  9  by manually pulling the cover off of the collar  13 . The collar  13  can be removed from the bottle assembly  1  by disengaging the threaded connection between the collar and the bottle  3 . More specifically, the collar  13  can be manually rotated with respect to the bottle  3  to thereby disengage the internal threads  61  of the collar from the external threads  27  of the top portion  10  of the bottle  3 . Since the nipple  11  is captured by the collar  13 , removal of the collar from the bottle assembly  1  results in removal of the nipple as well. The bottom closure member  65  can also be manually rotated with respect to the bottle  3  to thereby disengage internal threads  75  from the external threads  25  on the base portion  8  of the bottle  3 . Since the diaphragm  83  is captured by the bottom closure member  65 , removal of the bottom closure member from the bottle assembly  1  results in removal of the diaphragm as well. Once the bottom closure member  65  and diaphragm  83  are disengaged from the bottle  3 , the diaphragm  83  can be manually lifted from the bottom closure member  65 . Otherwise, the bottom closure member  65  can be turned upside down and the diaphragm  83  will fall out. 
     Thus, all of the components of the illustrated bottle assembly  1  can be easily separated and cleaned either manually or in a dishwasher. The bottle assembly  1  can be easily reassembled by reversing the disassembling process. 
     As illustrated in  FIG. 26 , an infant (or young child) can drink from the bottle assembly  1  by latching onto the upper tapered portion  49 a of the bulbous sidewall  49  of the nipple  11  with his/her lips as he/she would a breast. As illustrated, the cylindrical end  51  of the nipple  11  with the flow control valve  68  disposed therein is entirely received within the infant&#39;s mouth. The infant tilts the bottle assembly  1  to a drinking position thereby causing liquid to flow via gravity into the nipple  11  where is it blocked by the flow control valve  68  ( FIGS. 27 and 28 ). Next, the infant sucks to apply a vacuum to the nipple  11  and thereby to the flow control valve  68 . Once the vacuum pressure reaches or exceeds about 50 mm Hg, the flow control valve  68  will open as seen in  FIG. 29  and allow the liquid to pass from the liquid chamber  28  of the bottle  3  through the flow control valve and out the opening  53  in the nipple  11  for consumption by the infant. Once the vacuum pressure applied by the infant falls to or below the 50 mm Hg needed to keep the flow control valve  68  open (e.g., when the infant pauses to swallow), the flow control valve will move back to the closed position blocking the flowing of liquid. A typically infant will cycle between sucks and pauses to swallow about 60 times per minute. Thus, it is anticipated that the flow control valve  68  will open and close about 60 times per minute during a typically feeding. 
     Sucking on the nipple  11  and removing liquid from the liquid chamber  28  of the bottle  3  causes an internal vacuum to form within the liquid chamber. That is, the infant drinking liquid from the bottle assembly  1  causes the pressure within the liquid chamber  28  of the bottle  3  to drop below ambient pressure. In one suitable embodiment, more than 50% of the surface area of the first side  97  of the diaphragm  83  is subjected to the vacuum within the bottle  3  and more than 50% of the surface area of the second side  99  of the diaphragm is subjected to ambient pressure during use. Suitably more than 75% and even more suitably more than 90% of the surface areas of the first and second surfaces are subjected to vacuum and ambient pressure, respectively, during use. As a result, the diaphragm  83  is responsive to relatively low pressure differentials (i.e., the pressure difference between the liquid chamber  28  of the bottle  3  and ambient pressure) thereby making it easy for the infant to drink from the bottle assembly  1 . In one suitable embodiment, the diaphragm  83  is responsive to pressure differentials between about 2 (0.15 mm Hg) and about 4 inches of water (0.30 mm Hg). However, it is understood that the diaphragm  83  can be responsive to other ranges of pressure differentials. 
     The vacuum formed within the liquid chamber  28  of the bottle  3  draws the diaphragm  83  to move from a sealed position ( FIG. 25 ) to an unsealed position ( FIG. 26 ). More specifically, the vacuum causes the diaphragm  83  to flex away from the base panel  73  of the bottom closure member  65  thereby opening an air vent and allowing air (as indicated by the arrows in  FIG. 25 ) into the liquid chamber  28  of the bottle  3 . Particularly, flexure of the diaphragm  83  repositions the outer facing one of the first and second sealing elements  91 ,  93  away from the seat  77  of the base panel  73  of the bottom closure member  65  to allow air to flow in through two apertures  79  in the base panel of the bottom closure member, into the air gap  101  formed between the diaphragm  83  and bottom closure member, through the air passage  95  in the diaphragm, and into the liquid chamber  28  of the bottle  3 . As the vacuum pressure within the liquid chamber  28  of the bottle  3  approaches ambient pressure, the resiliency of the diaphragm  83  causes it to move back to the sealed position thereby preventing further air flow into the liquid chamber. Particularly, the outer facing one of the first and second sealing elements  91 ,  93  of the diaphragm  83  return to the seated position wherein the respective sealing element sealingly engages the seat  77  of the base panel  73  of the bottom closure member  65  and thereby blocks air flow into the liquid chamber  28  of the bottle  3 . 
     Air is trapped in the air passage  95  in the diaphragm  83  when the outer facing one of the first and second sealing elements  91 ,  93  of the diaphragm  83  is sealingly seated against the seat  77  of the base panel  73  of the bottom closure member  65 . This trapped air inhibits liquid contained in the liquid chamber  28  of the bottle  3  from entering the air passage  95  in the diaphragm. Inhibiting liquid from entering the air passage  95  in the diaphragm  83  significantly reduces the likelihood that liquid contained in the liquid chamber  28  of the bottle  3  will leak from the bottle assembly  1 . 
     Should the vacuum within the liquid chamber  28  of the bottle  3  reach or exceed approximately 10 mm Hg during use (e.g., if the vent member fails), the flow control valve  68  will allow air to flow through the valve and into the liquid chamber of the bottle. 
     As various changes could be made in the above constructions and methods 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. 
     When introducing elements of the present invention or the preferred embodiments(s) 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.