FIELD OF THE INVENTION
The present invention pertains generally to liquid dispensing valves and more particularly to mouth-operated liquid dispensing valves for use with flexible liquid containers, and methods for making same.
BACKGROUND OF THE INVENTION
Flexible liquid container systems are extensively used in recreational and sporting activities for carrying supplies of water or other nourishing fluids often referred to as sport-drinks. Such systems may be adapted to be carried by someone engaged in sporting activities such as cycling or mountain climbing, and are often used by these persons to drink liquids without pausing from the activities in which they are engaged.
An important component of a flexible liquid container system, particularly a system that is used during a sporting activity, is a valve that permits a user to rapidly ingest large volumes of liquid, while also providing a liquid tight seal for the container while not in use. To achieve these objectives, a commonly used system provides for a flexible container, a tube partially disposed in the container and extending therefrom, and a bite valve positioned on the exposed end of the tube.
A relatively simple bite valve for such a system is disclosed in U.S. Pat. No. 5,085,349. The valve has a body in the form of a tube having two flattened (opposite) sides, thus approximating a flattened ellipse in cross section, and having inlet and outlet ends. A plug valve proximate the outlet end of the tube has a slit formed therein, extending generally along the minor axis of the ellipse. A user operates the valve by compressing the flattened sides of the tube together, thereby distorting the plug and opening the slit to allow liquid to be expelled, typically by sucking into the user's mouth.
While clearly a simple arrangement, because it has no moving parts, this valve has certain shortcomings, particularly restricted flow rates and excessive weeping and dribbling. The flow rate of liquid through the valve is dependent upon the geometry of the slit and is restricted by two particular factors: the length of the slit and the shape of the slit mating surfaces. The size of the orifice created when the valve is actuated, and therefore the flow rate, is directly related to the length of the slit. The shorter the slit, the lesser the flow rate. Although a longer slit will obviously increase flow rates, it also will weaken the integrity of the seal and allow more weeping and dribbling.
In addition to the length of the slit, the shape of the slit mating surfaces impacts the size of the orifice under actuation. The leading edges of the slit, typically defined as those on the outlet surface of the plug, will determine the orifice boundaries and therefore the flow rate. The smoother and squarer the mating surfaces, the lesser the flow rate. (If the compression of the sides of the tube effects the distortion of the plug toward the outlet end, then the leading edges of the slit will be those on the inlet surface of the plug.) However, if the surfaces do not squarely mate with each other, the integrity of the seal will be weakened and more weeping and dribbling will occur.
Weeping and dribbling of liquid through the valve when not in use result at least in depletion of liquid resources for the user and also a gradual loss of valve integrity, not to mention the possibility of collateral damage to surrounding goods such as clothes. In the prior art, two particular means have been used to control weeping and dribbling: making the plug concave/convex with the convex side oriented toward the inlet end of the valve, and making the plug thicker so as to provide both greater contact area between the slit mating surfaces and a greater “spring-back” force to the plug to bias the slit in the closed position following actuation of the valve.
Although increasing the thickness of the plug, at least in the central area of the plug surrounding the slit, serves to help reduce weeping and dribbling, this increased thickness often requires greater physical force be applied by a user to operate the valve and open the slit.
Furthermore, although the convex inner surface of the valve plug acts as a self-energizing seal (i.e., when placed under pressure it forces the slit mating surfaces together and prevents leaking), under very low hydrostatic pressures fluid can weep past the seal, particularly after a high number of cycles has caused the material of the valve to lose some of its resiliency. The liquid container may be pressurized, or the container may be raised above the outlet to create a hydrostatic pressure head, thus generating the expelling force for the liquid through the valve. However, the contents of the liquid container are often not under any pressure at all, and therefore the sealing characteristics of this type of plug are greatly reduced, if not eliminated entirely.
SUMMARY OF THE INVENTION
The present invention relates to a bite valve diaphragm for use with liquid containers using a fluid delivery conduit. The design maximizes flow rates and minimizes weeping and dribbling when compared to conventional diaphragms of the prior art.
A feature of the invention is the incorporation of beveled or chamfered edges in a slit defined by the diaphragm. The diaphragm preferably comprises a cylinder portion and a diaphragm portion, although only a diaphragm portion is needed. If a cylinder portion is used, it may be circular in cross section, or have a cross section of other geometric forms such as generally elliptical. Preferably, the cylinder portion has an inner surface, an outer surface, an upstream end at a first perimeter, and a downstream end at a second perimeter wherein the upstream end is adapted to fit the conduit.
The diaphragm portion is coextensive with the second perimeter to prevent fluid entering the upstream end from exiting the downstream end. The diaphragm has an upstream surface, a downstream surface, and a perimeter coincident with the second perimeter. As noted previously, the cylinder portion is intended to provide the means by which the diaphragm is located on the fluid conduit or tube. It is contemplated that the diaphragm can also be directly located in the tube. In such a situation, the diaphragm becomes an insertable disk.
Formed in the diaphragm is an elongate slit defined by a first wall and second wall of the diaphragm wherein at least a portion of the first and second walls diverge towards the downstream surface of the diaphragm so as to create a notch in the downstream surface of the diaphragm at the slit. The creation of a notch or trough operates to maximize the orifice through which fluid will flow, while retaining sufficient material on the upstream side to maintain an effective sealing arrangement.
The incorporation of converging walls 40 and 42 to form a chamfer or bevel is intended to increase the volumetric flow of fluids during fluid expulsion actions. Turning to FIGS. 5a, 5 b, 6 a, and 6 b, it can be seen that for a given upstream gap 44, the minimum gap through which fluids must pass is greater with respect to a diaphragm incorporating the invention, i.e., gap 46 as compared to a diaphragm not incorporating the invention, i.e., gap 48. Thus, by reducing the degree of gap constriction by removing diaphragm material present at the downstream side of the diaphragm, an increased area through which fluid may flow is created. Naturally, by removing material at this point to chamfer the slit, the total area of contact between the slit boundaries is necessarily reduced, thus affecting weeping and dribbling properties.