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 forceNõChe liquild 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.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross section view of a bite valve assembly incorporating the present invention taken along the longitudinal axis and orthogonal to a slit in a diaphragm; Figure 1a is a cross section view of an alternative embodiment of the invention wherein a diaphragm is directly insertable into a fluid conduit and a cap is employed to retain the diaphragm therein; Figure 2 is a cross section view of the inner body, showing the details of the diaphragm; Figure 3 is a plan view of the inner body, showing the slit located along the minor axis of an elliptical diaphragm with chamfered or beveled edges thus forming a notch or trough; Figure 4 is a cross section view of the outer body, showing the plug and sleeve ; Figure 5a is a cross section view of the of the inner body, illustrating an increased fluid orifice when beveled or chamfered edges are employed regarding the slit ; Figure 5b is a plan view of the inner body of Fig. 5a, showing the area of the orifice of the actuated valve ; Figure 6a is a cross section view of the inner body of a prior art diaphragm design, illustrating a fluid flow constriction at the downstream end of the slit ; and Figure 6b is a plan view of the inner body of Fig. 6a, showing area of the orifice of the actuated valve.

DETAILED DESCRIPTION OF THE INVENTION Referring to the several Figures wherein like numerals indicate like parts, and more particularly to Fig. 1, a preferred embodiment of bite valve 10 is shown in cross section. Bite valve assembly 10 comprises resilient, elastomeric inner body 12 and resilient, elastomeric outer body 14, which are positioned co-axially with respect to each other such that inner body 12 is substantially surrounded by outer body 14, and both bodies 12 and 14 share longitudinal axis 16. Assembled

bite valve assembly 10 thus has inlet end 18 to receive a fluid conduit or fube, and outlet end 20. The interference fits between the two bodies 12 and 14 serve to lock and retain valve assembly 10 in the correct configuration while in use, but also provides for a convenient means to replace inner body 12, which may become worn through use.

Also shown in Fig. 1 is circumferential lip 58 positioned generally radially outward from the active portion of inner body 12. Lip 58 creates an enhanced area of localized resiliency to increase the restoring force present at the active portion of inner body 12, and decreases wear on diaphragm 22.

An alternative form of the invention is shown in Fig. 1a. instead of incorporating a cylinder portion to engage with outer body 14, only diaphragm 22' is present. Tube 70 is modified to receive diaphragm 22'and retention member or cap 80 frictionally fits over tube 70 to prevent unintentional escapement of diaphragm 22'.

The cross section view of inner body 12 in Fig. 2 and the plan view thereof in Fig. 3 show in greater detail the nature of slit 32. Inner body 12 has cylinder portion 24 and diaphragm portion 22. Cylinder portion 24 has a generally elliptical section, a smooth outer wall, and a pair of circumferential ribs 38. These ribs are formed to locate in corresponding complementary grooves 54 formed in outer body 14 as is best shown in Fig. 4. Diaphragm 22 has concave outer surface 26 and convex inner surface 28. Additionally, groove 34 is defined at the periphery of diaphragm 22 to receive complementary circumferential rib 52 as is best shown also in Fig. 4. Thus, the combination of mating grooves and ribs functions to retain body 12 in body 14 during use of bite valve assembly 10, as is best shown in Fig. 1.

Returning to Figs. 2 and 3, diaphragm 22 also defines slit 32, which extends from concave outer surface 26 through to convex inner surface 28.

Preferably, slit 32 intersects the longitudinal axis 16 and is coincident with the minor axis 36 of diaphragm 32. Slit 32 is intentionally formed to have a chamfered or beveled profile, thus forming a notch or trough defined by converging walls 40 and 42 for reasons that will now be described.

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.

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.

The following data describes the effect of modifying a prior art bite valve to incorporate the invention without encountering undesirable weeping and/or dribbling. To obtain the data, 15 standard slit bite valves were used; five were left unmodified for control, five were modified to remove material adjacent the upstream side of the slit by means of a sharpened blade, and five were modified to remove material adjacent the upstream side of the slit by means of a grinding tool. Chamfer or bevel angles relative to centerline ranged from about 30 to 45 degrees. Also tested, although not pertinent to the invention, was the effect of different fittings to connect the assembly to a fluid tube. In all tests, a 127cm water column and reservoir was used to supply water under pressure to the valve assembly, and the minor axis of the assembly measured about 9.53mm. The depth of material removal was generally limited to no more than 50% of the diaphragm thickness. Thus, for 80 mil. polyethylene material having a durometer value of 40-50, approximately 30-50 mil. remained for creating a seal at the gap after material removal. Sample Slit Flowrate (cc/min) Flowrate (cc/min) Flow loss due to No. Length w/barbed fitting without barbed barbed fitting mm) fitting (cc/min Beveled 1 6. 81 1850 2150 300 edge-razor # 2 6.99 1750 2000 250 cut 3 6. 99 2000 2350 350 4 6. 73 1800 2100 300 5 6.81 1800 2100 300 ---------------------------------------------------------- # Avg. 6.86 1840 2140 300 Std. Dev. 0.127 96 129 35 Beveled # 6 6.81 1900 2150 250 edge-tool 7 7.06 1950 2250 300 ground # 8 6.93 1900 220 300 9 6.99 1950 2250 300 10 6. 81 1850 2150 300 ---------------------------------------------------------- # Avg. 6.91 1910 2200 290 Std. Dev. 0. 102 42 50 22 Prior art bite # 11 7.06 1350 1450 100 valve 12 7. 09 1350 1500 150 13 6. 76 1300 1450 150 14 6.65 1250 1350 100 15 6. 99 1350 1450 100 ---------------------------------------------------------- Avg. 6.91 1320 1440 120 Std. Dev. 0.203 45 55 27