Abstract:
A feeding bottle ( 10 ) comprises a container ( 16 ), a teat ( 12 ) and a collar ( 14 ) to screw the teat ( 12 ) onto and seal the container ( 16 ). A vent assembly ( 18 ) is mounted between the teat ( 12 ) and the container ( 16 ) and includes a vent tube ( 22 ) passing down to a position close to the base of the container ( 16 ) and having a one way valve ( 34 ) allowing air to pass into the container ( 16 ) on application of suction to the teat ( 12 ) but preventing liquid flowing into the vent tube ( 22 ), together with a valve flange ( 36 ) acting as an anti-choke member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a U.S. National filing under §371 of International Application No. PCT/GB2005/001883, with an international filing date of 17 May 2005, now pending, claiming priority from Great Britain Application No. GB2004/10993.0, with a filing date of 17 May 2004, now pending, and herein incorporated by reference. 
     TECHNICAL FIELD 
     The invention relates to a feeding bottle for example a vented feeding bottle. 
     BACKGROUND OF THE INVENTION 
     Conventional feeding bottles comprise a container and a teat held on the container by a screw-on collar. A problem with conventional feeding bottles is that as an infant sucks on the teat a negative pressure builds up within the container as a result of which it becomes progressively more difficult to feed which can give rise to problems such as colic. 
     Various solutions have been proposed for alleviating the problem for example providing valves allowing air ingress. One example of such a solution is described in European patent application EP0845971. According to this document a feeding bottle includes a reservoir tube communicating at its upper end with a vent to atmosphere. The reservoir tube has a bulbous upper reservoir portion with an air tube projecting down into it from the air vent. An air conduit portion projects down from the reservoir portion to a point close to the bottom of the container. In the upright position the container is filled with liquid nearly to the height of the reservoir portion. When the container is inverted the end of the air conduit portion projects above the level of the liquid and the liquid previously in the air conduit portion drains into the reservoir portion and sits below the end of the air tube. As a result an air passage is provided from the vent via the air tube into the reservoir portion and through the air conduit to the bottle such that pressure equalisation is provided when the infant drinks. However, there are various disadvantages to this arrangement. Firstly a very complex arrangement is required. Furthermore because no valves are provided, if the infant distorts the teat while feeding for example by biting down on it there is less resistance and liquid is pushed away from the teat. 
     Another approach is described in U.S. Pat. No. 6,499,615 which describes a bottle having an angled neck and a valved vent tube. Once again complex and specialised components are required for this arrangement which also presents cleaning difficulties and even choking hazards as a result of the numerous small parts involved. 
     Furthermore, in known valved, vented feeding bottles, during the bottle feeding process the pressures fluctuate between positive and negative throughout the feed. When the infant bites down on or compresses the teat during feeding this action creates positive pressure in the bottle as the milk is pushed back into the bottle, acting on the valve to close it and directing milk flow out of the teat. As the infant creates suction to draw more milk from the bottle a negative pressure is induced in the bottle as milk is dispensed and when this occurs the valve at the end of the tube opens allowing air into the bottle. However in known systems a relatively significant negative pressure is required before the valve opens to allow air to vent such that the infant must suck unnaturally hard before pressure equalisation takes place. Accordingly known systems do not closely mimic natural feeding. 
     SUMMARY OF THE INVENTION 
     The invention is set out in the claims. Because the pressure at which the valve opens is minimised, the valve can vent at the very low negative pressures associated with infant feeding as a result of which the bottle provides a close similarity to natural breast feeding. 
     Furthermore, because of the provision of an anti-choke portion, feeding hazards are reduced and it is found also that the anti-choke portion provides a useful stirring/mixing member. Furthermore, by providing a feeding bottle insert with a sealing portion which itself provides a liquid passage as well as an air vent passage a simple modular constructions is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described by way of example, with reference to the figures of which: 
         FIG. 1  is a sectional side view of a feeding bottle according to a first embodiment of the present invention; 
         FIG. 2  is a sectional view of a detail of the feeding bottle insert shown in  FIG. 1 ; 
         FIG. 3   a  is a sectional perspective view of a valve and valve flange assembly according to an embodiment of the present invention; 
         FIG. 3   b  is a top plan view of the valve and valve flange assembly of  FIG. 3   a;    
         FIG. 3   c  is a front view of the valve and valve flange assembly of  FIG. 3   a;    
         FIG. 3   d  is a side view of the valve and valve flange assembly of  FIG. 3   a;    
         FIG. 3   e  is a bottom plan view of the valve and valve flange assembly of  FIG. 3   a;    
         FIG. 4   a  is a perspective view of an alternative valve and valve flange assembly according to and embodiment of the present invention; 
         FIG. 4   b  is a bottom plan view of the valve and valve flange assembly of  FIG. 4   a;    
         FIG. 4   c  is a side view of the valve and valve flange assembly of  FIG. 4   a;    
         FIG. 5   a  is a sectional side view of a feeding bottle according to a second embodiment of the present invention; 
         FIG. 5   b  is plan view of the teat according to the second embodiment of the present invention; 
         FIG. 6   a  is a sectional side view of a detail of the feeding bottle according to a third embodiment of the present invention; 
         FIG. 6   b  is plan view of the teat according to the third embodiment of the present invention; 
         FIG. 7   a  is a plan view of an alternative feeding bottle head portion; 
         FIG. 7   b  is a sectional view along the line A-A of the feeding bottle head portion of  FIG. 7   a;    
         FIG. 7   c  is a sectional view along the line B-B of the feeding bottle head portion of  FIG. 7   a  and 
         FIG. 7   d  is a perspective view of the feeding bottle head portion of  FIG. 7   a.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , a feeding bottle designated generally  10  includes a teat  12  mounted by a screw collar  14  onto a container  16 . As is conventional, the collar  14  includes a central orifice through which the teat protrudes and the teat includes a flange of similar diameter to the container such that when the collar is screwed down a seal is formed by pressure of the collar on the flange of the teat. 
     The feeding bottle  10  further includes a vent assembly in the form of a neck insert  18  including a head portion  20  and a vent tube  22  projecting downwardly from the head portion. The head portion  20  includes a liquid conduit  24  providing communication between the container  16  and the teat  12  such that when the feeding bottle is inverted liquid passes via the liquid conduit  24  from the container into the teat allowing the infant to feed. Isolated from the liquid conduit  24  the head portion also includes an air passage  26  communicating with the vent tube  22  at one end and with atmosphere at the other end. 
     The head portion  20  includes an upper flange portion  28  of similar diameter to the container and arranged to fit on the lip of the container to be gripped in a liquid tight condition by the flange of the teat  12  pressed down by the collar  14  as described above. The flange portion  28  is of sufficient thickness to allow a generally radially extending bore to be formed inwardly from the cylindrical side wall providing the air passage  26 . The air passage opens to atmosphere via the screw threads of the collar  14  and is sealed against liquid passage by virtue of the seal formed by the neck insert flange portion  28  against the lip of the container  16 . 
     The air passage  26  communicates at its other end with a formation  30  provided on the lower face of the head portion  20  comprising an open-ended chamber on to which the vent tube  22  is an airtight push fit. The vent tube  22  extends downwardly nearly to the bottom of the container and includes at its lower end  32  a one-way valve  34 . In the embodiment shown the valve  34  comprises a duck-billed valve of well-known type which allows passage of air in one direction, into the container, but prevents the flow of liquid in the opposite direction, into the vent tube  22 . Also provided at the lower end  32  of the vent tube  22  is a valve flange  36  which in the embodiment shown is in fact formed integrally with the valve  34  and both of which are a push fit or otherwise airtight connection to the vent tube  22 . The valve flange  36  can form, for example, a ring around and concentric with the vent tube  22  and joined thereto by a web or ribs. The valve flange allows improved mixing and prevents a choking hazard in the event that the valve  34  should become detached for any reason. 
     In use the neck insert  18  is assembled (or pre-assembled) by fitting the valve  34  and flange  36  on to the vent tube  22  and fitting the vent tube  22  at its other end to the corresponding formation  30  of the head portion  20 . The container  16  is filled and the neck insert  18  is placed on the upper lip of the container  16 . The teat  12  is then placed on top of the neck insert  18  and the assembly is liquid sealed by screwing the collar  14  down as discussed in more detail above. When mixing is required this can be facilitated by virtue of the valve flange  36 . When the container is inverted liquid passes from the container  16  through the liquid conduit  24  in the neck insert  18  into the teat  12 . When the infant sucks or feeds on the teat  12 , causing a pressure drop in the container  16 , air enters the container via the air passage  26 , the vent tube  22  and the valve  34  such that pressure is equalised and a vacuum build-up is greatly reduced. 
     Referring to  FIG. 2  the head portion  20  of the neck insert  18  is shown in more detail. As can be seen the head portion includes a flange portion  28  that is generally disc shaped and provides a seal around the neck of the container  16  (not shown) and a liquid conduit  24  in the direction perpendicular to the plane of the flange. The air passage  26  passes through the cylindrical wall of the flange portion  28  generally to the centre of the flange portion  28  providing a passage to the formation  30  and vent tube  22  (not shown). 
     Referring to  FIGS. 3   a  to  3   e  the valve  34  and valve flange  36  are shown in more detail and in particular it will be seen that a ring-shaped or other profile of valve flange  36  can be provided and mounted in any appropriate manner for example by virtue of spokes extending from the central hub  35  on which the valve  34  is mounted or by an apertured web  37  as shown. 
       FIGS. 4   a ,  4   b  and  4   c  show an alternative one way vent valve that can be implemented in the embodiments of present invention. The hemispherical valve  40  comprises a hemispherical shaped membrane with a central slit  41  which allows the passage of air therethrough. Any suitable cut such as a cross is also possible. The slit or cut is dimensioned to allow low pressure air venting as well as high temperature sealing. 
     The hemispherical valve of  FIGS. 4   a  to  4   c  could also be used for other applications. For example, it could be located on the apex of the teat to allow the passage of fluid therethrough or on the flange of the teat to allow passage of air therethrough. 
     The dimension, material and construction of the valve  34  or  40  is of particular significance in obtaining a natural feeding action for the bottle. Most valving systems currently known allow a teat to vent at approximately 50 mB (milliBar) by virtue of the closing force determined by the resilience of the valve walls surrounding the slit, for example because of their stiffness. As a result, in use, the infant must exert an unnaturally high sucking force before venting can take place which can give rise to problems and results in sucking action more powerful than that required in natural feeding. However in known systems such a high resilient closing force is required to ensure that the valve does not leak milk into the vent tube, for example when the infant exerts squeezing pressure on the teat. 
     The valve  34  or  40  according to the present invention, on the other hand, is constructed such that a negative pressure in the region of 1 to 25 mB, more preferably 5 to 15 mB and most preferably 10 mB will be sufficient to open the valve to allow venting when the infant sucks on the bottle, requiring significantly less suction by the infant and a more natural feeding action. In particular this is allowed because of the recognition, according to the invention, that it is only necessary to prevent leakage of milk into the valve and vent tube when the bottle is in the upright position (and hence the valve is immersed in milk) whereas when the infant is sucking on the teat the bottle will tend to be inverted such that the valve is positioned above the level of the milk. Even if the valve opens when it is immersed in milk, no liquid will enter the valve and vent tube 
     Accordingly the invention recognises that a less significant resilient closing force is required for the valve because of the additional force applied to the sides of the valve when the bottle is standing upright as a result of the head of pressure exerted by the milk in the bottle. This force provides the additional closing force sufficient to prevent leakage into the valve and vent tube. Accordingly when the infant is drinking from the bottle in its inverted position, because the valve has a smaller resilient closing force it opens under a lower negative pressure as a result of which a more natural feeding action is represented. 
     It will be appreciated that the skilled reader can fabricate an appropriate duck-billed valve or hemispherical valve to meet the criteria set out above using routine trial and experimentation, for example by varying the wall or membrane thickness and hence stiffness of valves and applying an appropriate negative pressure to obtain venting at the desired pressure and/or by immersing the valves in liquids of a similar density to that of milk or other fluids used by the infant with an appropriate head of pressure, for example 5 to 10 cm. Preferably the valve is fabricated so that it remains closed even with a low head of pressure, for example 5 mm. 
     In the specific embodiment shown with respect to  FIGS. 3   a  to  3   e , the valve is formed of pure silicone rubber with typical 30 to 60 Shore A hardness as available from any silicone supplier such as GE, Bayer, Dow, Wacker, Rhone Poulenc. Both liquid silicone and compression moulding silicone grades are suitable for the present invention as they provide high heat stability, important for repeated heat sterilising methods. Other grades may also be suitable. The valve walls having a valve thickness 0.5 mm. Viewed from the front the duck-billed valve forms the shape of an inverted triangle of height 10.0 mm and base 8.0 mm. Viewed from the side the duck-billed valve is generally rectangular in cross-section having a width of 7.0 mm. A slit is formed on the exit end of the valve by a cut with a length of 2.5 mm to 4 mm. It is found that this configuration provides the desired operating range and in particular an ability to open up under a negative pressure of just 10 mB. 
     In the specific embodiment shown with respect to  FIGS. 4   a  to  4   c , the hemispherical valve is formed of pure silicone rubber with typical 30 to 60 Shore A hardness as available from any silicone supplier such as GE, Bayer, Dow, Wacker, Rhone Poulenc. Both liquid silicone and compression moulding silicone grades are suitable for the present invention as they provide high heat stability, important for repeated heat sterilising methods. Other grades may also be suitable. The key dimensions of the hemispherical valve  40  for high temperature sealing are its radius, wall thickness, length of central slit  41  and material softness. The hemispherical valve has a radius of 2 mm to 5 mm, most preferably 3.5 mm, and a wall thickness of 0.3 mm to 0.7 mm, most preferably 0.5 mm. The central slit dimension is in the region of 2.5 mm to 4.0 mm. It is found that this configuration provides low level suction but is also inherently strong enough to withstand pressures associated with liquid up to boiling point temperature without leakage. 
       FIGS. 5   a  and  5   b  show a second embodiment of the present invention in which there is an alternative air entry system. An air passage is formed by an air inlet aperture  51  on the flange of the teat  12  and an air conduit member  50  projecting downwardly of the teat. The air conduit member  50  provides communication between atmosphere and a vent tube  22  which is attached to the air conduit member with an airtight push fit. The air conduit member  50  can be integrally formed on the flange of the teat  12 , for example in the form of a stalk projecting downwardly of the teat at the teat aperture  51 . The teat  12  is mounted by screw collar  14  onto container  16 . 
     In a third embodiment of the present invention, as shown in  FIG. 6 , the air conduit member  56  is integrally formed on a support member, for example in the form of a sealing ring  52 . The air conduit member  56  projects downwards of the sealing ring  52 . The sealing ring  52  is of similar diameter to container  16  and arranged to fit on the lip of the container to be gripped in a liquid tight condition by the flange of teat  12  pressed down by collar  14 . The sealing ring  52  additionally provides support for the flange of the teat  12 . A recess  55  is formed on the flange of the teat  12  which leads to an air inlet aperture  53  in the teat. An air passage is formed between the flange recess  55  and the screw collar  14  which allows for the passage of air from atmosphere through the aperture  53  on the flange of the teat, which is suitably aligned above the conduit member  56  on the ring  52 , and air conduit member  56  to the vent tube  22 , as shown by dotted arrow  54 . The vent tube  22  is attached to the air conduit member  56  with an airtight push fit. 
       FIGS. 7   a  to  7   d  show an alternative feeding bottle insert head portion  70 . As can be seen the head portion includes hub  71  connected to a rim  72  by spokes  73 . A liquid conduit is formed by spaces  74  between the hub  71 , rim  72  and spokes  73 . The liquid conduit provides communication between the container  16  and the teat  12  (neither shown) such that when the feeding bottle is inverted liquid passes from the container through the spaces  74  and into the teat allowing an infant to feed. 
     At least one of the spokes  75  is of sufficient thickness to allow a generally radial bore to be formed therethrough providing an air passage  76  to an open ended chamber  77 . The air passage  76  communicates the vent tube  22  (not shown), which is attached to an open ended chamber  77  by push fit and projects downwardly of the head portion  70 , to the atmosphere via the screw threads of the collar  14  (not shown). 
     An annular recess  78  in the underside of the generally annular shaped rim  72  provides a liquid tight seal between the head portion and the container  12  (not shown). The recess  78  is formed such that an inner surface  79  fits inside the container and an upper surface  80  rests on the lip of the container. 
     It will be appreciated that the various parts of the feeding bottles described above can be made with any appropriate material and in particular the teat  12 , collar  14  and container  16  can be made of any standard material. The vent tube  22  is preferably made of generally rigid, inert material such as plastics material and the valve  34  or  40  can be made of silicone rubber or other appropriate material for the purposes required. The flange  36  is preferably made of rigid plastic material allowing mixing and an anti-choke function and can be two-shot moulded with the valve  34  or  40  if appropriate. In the embodiments discussed various elements are connected by push fit allowing easy disassembly and cleaning but any appropriate manner of connection can be adopted and indeed where appropriate the various parts can be formed integrally or non-detachably. The head portion  20  is preferably of a semi-rigid material ensuring that the air passage  26  is not closed by deformation of the flange portion  28  but at the same time a reliable liquid tight seal is provided at the neck of the container. Similarly the support member of the third embodiment is preferably of a semi-rigid material ensuring that the air conduit member  56  is not closed by deformation when push fitted to the vent tube  22  but at the same time a reliable liquid tight seal is provided at the neck of the container  16 . 
     The neck insert  18  can be integral with the container/collar or can be detachable as appropriate for cleaning purposes. In particular the neck insert  18  can provide a simple modular attachment to a standard feeding bottle and in many cases the existing collar can be used in cooperation with the neck insert  18 . Alternatively the neck insert  18  can be provided with a specially tailored collar of appropriate depth to ensure good screw-thread engagement. 
     As a result of the arrangement described herein various advantages are provided. The valve allows natural feeding by venting at very low pressure. Because the vent tube  22  is valved at its base, pressure equalisation is provided within the container without allowing the infant to deform the teat and push liquid away from the teat. Also, because the valve provides a liquid seal there is no risk of leakage of liquid through the neck insert and down the side of the container. A simple and modular arrangement is provided for the neck insert. By virtue of the addition of a valve flange mixing and stirring can be improved whilst choke hazards can be avoided. 
     It will be appreciated by a skilled person that any appropriate type of valve can be used in place of the duck-billed valve or hemispherical valve described above. The dimensions of the container and the various components can be varied as appropriate and the specific positioning of the various elements can be rearranged as appropriate. Similarly any other appropriate shape and positioning of the valve flange can be adopted. Although the discussion above is directed to a feeding bottle a similar approach can be used in any drinking vessel with any type of mouthpiece or feeding or drinking closure where the desire is to provide pressure equalisation.