Abstract:
An improved nursing bottle is presented which possess a novel venting system that allows ambient air to enter the nursing bottle to equalize internal and external pressures and prevent nipple collapse. Preventing nursing bottle nipple collapse reduces the amount of sucking by infants required to extract milk from the bottle and eliminates air in the infant&#39;s stomach. Liquid is prevented from exiting the nursing bottle by means of capillary action. The invention can be utilized with any standard nursing bottle.

Description:
FIELD OF THE INVENTION 
   The invention relates to nursing bottles. More particularly, the invention relates to nursing bottles taking advantage of an air vent to equalize the interior pressure of the bottle with outside air pressure during use. 
   BACKGROUND OF THE INVENTION 
   Babies are born with the instinct to suckle milk from their mother&#39;s breasts, but it is often necessary for them to drink liquids from other sources. It is common throughout the world to feed liquids to babies in nursing bottles, also known as baby bottles. A nursing bottle is used by filling cylindrical container with liquid, securing a flexible nipple to the open end of the container, inverting the bottle, and placing the nipple into the baby&#39;s mouth. The baby then sucks on the nipple to drink the liquid. None of these nursing bottles completely solves the problem of maintaining the interior of the bottle at atmospheric pressure while preventing leaks and spills. They also do not provide a simple user-friendly system for mothers. Accordingly, a demand still exists for a nursing bottle, which prevents the formation of a partial vacuum inside the bottle during nursing yet does not result in spills, and is simple to use. 
   SUMMARY OF THE INVENTION 
   The invention is an improved nursing bottle and vent system to be filled with liquid and capped with a nipple. The interior of the nursing bottle remains at atmospheric pressure when the bottle is inverted during use. The vent system comprises: a vertical double-ended capillary tube, a wheel-and-spoke shaped circular insert that has a radially central housing for the capillary tube with a plurality of open air passages from the capillary tube to the screw threads of the container. 
   Fluid passes from the bottle to the nipple through the spokes of the wheel comprising the insert. When the bottle is inverted, an air passage is established from the open end of the capillary tube down inside the container to the vents in the insert spokes to the screw thread area of the container top, to carry ambient air into the container and thereby maintain atmospheric pressure. 
   The general object of this invention is to provide an improved vent system that will be applicable to any approved and in-use nursing bottle. A more particular object is to provide a vent system, which prevents the formation of a partial vacuum inside the bottle during nursing, yet does not result in spills. 
   It is another object of this invention, as an alternate embodiment, to provide a nursing bottle vent system which does not need cleaning because it is disposable. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is perspective view of the assembled invention 
       FIG. 2  is an exploded view of the invention 
       FIG. 3  is a cross-section of the top of the invention 
       FIG. 4  is a bottom view of the nipple 
       FIG. 5  is a top view of the insert 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2  show the preferred embodiment of the vent system. The vent system contains two components, a wheel-and-spoke shaped insert  105 , and a capillary tube  106 . The two components are separate and capable of easy disassembly and reassembly for ease of cleaning and replacement. 
   A conventional nipple  103  and nipple cap  102  is shown in  FIG. 2 . Although the nipple  103  and nipple cap  102  are not part of this invention, the insert  105  part of this invention makes use of the base  110  of the nipple  103  to create the ambient air passage with the plurality of tunnels  107  of the insert  105 . The nipple  103  usually includes a flat rubber circular base  110 , which usually rests on the nursing bottle neck  111 . 
   The insert  105  of this invention is designed to match the nipple base  110  dimensions of available nipples  103 . The tunnels  107  in the insert  105  are completely enclosed inside the insert  105 , and lead air from the screw threads  112  to the central housing  114  of the insert  105 . The nipple cap  102  attaches to the bottleneck  111  by means of the screw threads  112 , the insert  105  of this invention is pressed against the nipple  103  by means of the pressure exerted by the screw threads  112  when the nipple cap  102  is screwed on. 
   The insert  105  is molded as a single piece, and has a central housing  114  to receive the capillary tube  106 . When the nursing bottle  101  is assembled for use, the capillary tube  106  fits into the central housing  114  of the insert  105  by frictional fit. The frictional fit is sufficient to provide a seal and thereby prevent liquid from escaping. 
   The capillary tube  106  extends to a point near the bottom of the nursing bottle  101 . The open end of the capillary tube  106  should be within about 1 cm of the bottom of the bottle. This point needs to be in the bottle&#39;s air space when the bottle  101  is inverted. 
   The liquid in the container should not exceed a certain level. In  FIG. 1 , a line  115  permanently marked on the side of the bottle  101  shows the maximum liquid level. This marked line  115  is typically at or about the point of equalizing between the liquid and the capillary tube  106 . 
   The second component of the preferred embodiment of the vent system is the capillary tube  106 . The capillary tube open end  108  is near the bottom of the bottle  101 . When the bottle  101  is upright and contains liquid, the liquid enters the capillary tube open end  108  and reaches the same level inside the capillary tube  106  as in the bottle  101 . 
   The primary purpose of the capillary tube  106  is to provide a passage for ambient air into the bottle  101  when it is inverted and the liquid contents are being withdrawn through the nipple  103 . To achieve the capillary action, the cross-sectional area of the liquid inside the capillary tube  106  is very small. A cross section of 0.025 sq. mm is adequate. 
   When the bottle  101  is inverted, the outside pressure over the inside pressure will force the very small amount of liquid in the capillary tube  106  to flow back into the bottle  101 , clearing the capillary tube  106  for ambient air to enter the interior of the bottle  101  by flowing through the air tunnel formed by the insert  105  and the capillary tube  106 . Liquid will flow normally from the bottle through the spaces  120  between the spokes of the insert  105 . 
   The operation of the preferred embodiment of this invention is as follows. An appropriate-sized nursing bottle is obtained. The capillary tube  106  is inserted into the central housing  114  in the insert  105 . These two components are then placed in the bottle as in  FIG. 2  and the nipple  103  is placed over the insert  105  as shown. The nipple cap  102  is then screwed down over the nipple  103  as usual and the nipple cap  102  holds the base of the nipple  103  against the top of the insert so that the plurality of tunnels  107  in the insert  105  form a passage to the outside air. 
   Because of its placement in the bottle  101 , the capillary tube  106  is then filled with liquid. The liquid level in the tube should not substantially exceed the marked fill line, i.e., the point of equalizing between the liquid level in the bottle and the tube. When the bottle  101  is inverted, the liquid in the capillary tube  106  remains in the tube due to the capillary effect. This phenomenon ensures that: this amount of liquid small as it may be (due to the tiny section of the capillary tube), will not spill out through the insert tunnel  107 ). Immediately after the nursing starts, the decrease in air pressure in the bottle  101  will force the ambient air to enter the interior of the bottle  101  by flowing through the plurality of tunnels  107  of the insert  105  and the tube  106 . Thus, the interior of the bottle  101  will remain at ambient atmospheric pressure during use and the baby nursing from the bottle is not forced to suck so hard that air is inadvertently swallowed. As a result, the chances of colic are greatly reduced. 
   While the preferred embodiment of the invention has been described, modifications can be made and other embodiments of this invention realized without departing from the intent and scope of any claims associated with this invention.