Abstract:
The present invention provides devices and methods for dispensing fluids. By controlling the relationship between valve bodies and elastomeric sheaths that enclose them, one may reduce or eliminate backflow, thereby protecting the integrity of the fluid to be dispensed. Thus, the elastomeric sheath and valve body of the present invention may be used to form a one-way valve for dispensing fluid from a collapsible container.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/795,530, filed Apr. 27, 2006. The entire disclosure of that application is incorporated by reference as if set forth fully herein. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a system for dispensing fluids. 
       BACKGROUND OF THE PRESENT INVENTION 
       [0003]    There is a great need in many industries to dispense fluid products that are susceptible to oxidation and contamination safely. Many products lose their freshness, potency and/or sterility after only a brief period of use. This period or “use life” varies from product to product. 
         [0004]    Generally, when fluids are dispensed from a valve, the volume of product delivered from the valve is replaced with an equivalent volume of air. Exposure to this ambient air leads to the entry of oxygen into the container and potentially to contact with contaminants in the air such as microorganisms, atmospheric gases, moisture and dust particles. Consequently, the quality, potency, safety and/or sterility of the remaining product can be compromised by the air and potential contaminants within it. Accordingly, most fluid products are delivered in containers with preservatives. 
         [0005]    A small segment of fluid products are delivered in aerosol dispensers and unit dose packaging. Aerosols are limited to high-pressure applications, and they contain highly flammable solvents. Thus, their use life ends in hazardous waste, and their use has long been associated with serious environmental consequences. Unit dose packaging is also problematic; it is the most expensive approach to sterile packaging. Another disadvantage of unit dose packaging is the opportunity for users to save the unpreserved (and no longer sterile) product remaining in the single dose dispenser and to use it on subsequent occasions. This type of noncompliant usage can result in contaminated fluid being dispensed to a patient. 
         [0006]    Many industries, including the pharmaceutical, cosmetics, food and beverage industries, depend on the proper preservative ingredients to address product stability, safety and efficacy. However, there are no global standards for preservatives, and there are no ideal preservatives. 
         [0007]    One system for maintaining the integrity of fluids to be dispensed is described in the U.S. Pat. No. 6,766,816, issued to Secondo (the “&#39;816 patent”). The &#39;816 patent describes a collapsible dispensing system with a conical one-way valve comprised of a valve body and an elastomeric sheath for dispensing flowable materials where the inside diameter of the sheath is smaller than the outside diameter of the valve body prior to placement over the valve body to form a seal. 
         [0008]    However, there is a need for better contamination-safe, propellant-free delivery systems for consumer products that can be easily manufactured and assembled. A delivery system that could extend product use life, improve product performance, reduce the need for harmful preservatives or work in tandem with gentler preservatives would provide a significant public health benefit. 
         [0009]    The present invention addresses this need by providing devices and methods for delivering fluid under positive pressure through a one-way valve from a collapsible container so that backflow of air and contaminants into the remaining product in the container is prevented. 
       SUMMARY OF THE PRESENT INVENTION 
       [0010]    According to one embodiment, the present invention is directed to an improved dispensing system. This dispensing system comprises a sheath that envelops and seals against the outside surface of a conical one-way valve body as in the &#39;816 patent, for propelling and evacuating flowable materials through and out of the valve while preventing backflow of air and contaminants from reaching remaining container content. Also, the sheath is of a smaller diameter than the valve body prior to assembly over and against the outside surface of the valve body. Additionally, the sheath has a greater thickness at the inlet end of the valve than at the outlet end of the valve for providing greater elastic restoring force in evacuating fluid through and out of the valve. 
         [0011]    According to another embodiment, the difference in the diameter of the valve body and the smaller diameter sheath is greater at the inlet end than at the outlet end thereby providing greater sealing tension against the outside surface of the valve body at the inlet end of the valve than at the outlet end of the valve. 
         [0012]    According to another embodiment, the sheath has a greater thickness at the inlet end than at the outlet end and the difference in the diameter of the valve body and the smaller diameter sheath is greater at the inlet end of the valve than at the outlet end of the valve. 
         [0013]    These embodiments provide greater sealing tension and elastic restoring force at the inlet end of the valve than at the outlet end of the valve. Consequently, there is an increased tension of the valve seals and an aid to having fluid flow only in an outward direction. Due to these improved designs, the sheath will collapse and seal against the outside surface of the valve body at the inlet end before sealing at the outlet end upon the reduction of fluid pressure on the inlet port(s). Accordingly, backflow of air or product into the remaining contents of the container is effectively prevented. 
         [0014]    The present invention also provides a one-way valve that can be easily manufactured. For example, in some embodiments the present invention provides two and three component valve assemblies that can be produced at a low cost. For example, the present invention can comprise a rigid, vented sleeve laterally enclosing the elastomeric sheath for limiting the radially outward expansion of the sheath and for preventing any build up of air pressure between the sheath and the sleeve. Further, the inside surface of the enclosing sleeve and the corresponding expansion chamber formed between the enclosing sleeve and the elastomeric sheath may be of a roughly conical design. However, even if the inside surface of the enclosing sleeve is roughly conical, the outside surface of the enclosing sleeve need not be conical in shape. 
         [0015]    According to another embodiment, the present invention provides a one-way valve with improved ease of assembly. In this embodiment, the present invention has a conical valve body and a conical elastomeric sheath where not only the shape of the components facilitates the lateral enclosure of the sheath along the outside surface of the valve body. The increased elasticity provided by greater sheath wall thickness at the inlet end and/or the reduced interference fit of the sheath at the outlet end further eases assembly of the unit. Although a conical design of the one-way valve is preferred for some uses, in other embodiments, the one-way valve can be of a cylindrical design. 
         [0016]    Under another embodiment the present invention provides: a valve assembly for dispensing flowable materials, wherein said valve assembly comprises: (a) a valve body having a longitudinal bore therethrough; and (b) an elastomeric sheath having a longitudinal bore therethrough, wherein said elastomeric sheath has an inlet end and an outlet and said inlet end has a wall thickness and said outlet end has a wall thickness wherein the wall thickness of the inlet end is greater than the wall thickness at the outlet end and wherein said valve body and said elastomeric sheath are conically shaped, and positioned such that said longitudinal bore of said valve body and said longitudinal bore of said elastomeric sheath are coaxial. 
         [0017]    Under another embodiment, the present invention provides a valve assembly for dispensing flowable materials, wherein said valve assembly comprises: (a) a valve body having a longitudinal bore therethrough, wherein said valve body has an outer inlet valve body diameter and an outer outlet valve body diameter; and (b) an elastomeric sheath having a longitudinal bore therethrough and the elastomeric sheath has an inner inlet elastomeric sheath diameter and an inner outlet elastomeric sheath diameter, wherein the difference between the outer inlet valve body diameter and the inner inlet elastomeric sheath diameter is greater than the difference between the outer outlet valve body diameter and the outer elastomeric sheath, wherein said valve body and said elastomeric sheath are conically shaped, and positioned such that said longitudinal bore of said valve body and said longitudinal bore of said elastomeric sheath are coaxial 
         [0018]    The present invention also provides methods for dispensing fluids using the assemblies of the present invention. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0019]    Both the organization and method of operation of the invention, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the figures and the following description. The figures are not intended to limit the scope of this invention, but merely to clarify and to exemplify the invention. 
           [0020]    For a more complete understanding of the present invention, reference is now made to the following figures. 
           [0021]      FIG. 1  shows a side cross sectional view of a valve assembly according to one embodiment of the present invention. 
           [0022]      FIG. 1A  shows a side cross sectional view of a valve assembly according to an alternate embodiment of the present invention. 
           [0023]      FIG. 1B  shows a partial perspective view of a valve assembly according to another alternate embodiment of the present invention. 
           [0024]      FIG. 1C  shows a partial perspective view of a valve assembly according to another alternate embodiment of the present invention. 
           [0025]      FIG. 2  shows a side cross sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0026]      FIG. 2A  shows a side cross sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0027]      FIG. 2B  shows a partial perspective view of the valve assembly of  FIG. 2A . 
           [0028]      FIG. 3  shows a side cross sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0029]      FIG. 4  shows a side cross-sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0030]      FIG. 4A  shows a side cross-sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0031]      FIG. 4B  shows a partial perspective view of the valve assembly of  FIG. 4A . 
           [0032]      FIG. 5  shows a side cross sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0033]      FIG. 6  shows a side cross sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0034]      FIG. 7  shows a side cross sectional view of a valve assembly according to another alternate embodiment of the present invention. 
           [0035]      FIG. 8  shows a side cross sectional view of the valve assembly according to  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    A detailed illustrative embodiment of the present invention is disclosed herein. However, techniques, systems and operating structures in accordance with the present invention may be embodied in a wide variety of forms and modes. Consequently, the specific structural and functional details described herein are merely representative. 
         [0037]    Additionally, any of the features of the various embodiments described herein can be used in conjunction with features described in connection with any other embodiments disclosed unless otherwise specified. Accordingly, features described in connection with the various or specific embodiments are not to be construed as not suitable in connection with other embodiments disclosed herein unless such exclusivity is explicitly stated or implicit from the context. 
         [0038]    Referring first to  FIG. 1 , depicted is a side cross sectional view of a valve assembly comprised of a valve body  21  and an elastomeric sheath  23 . Both of these parts are conically shaped. Valve body  21  has inlet end  27  and outlet end  29 . Elastomeric sheath  23  has inlet end  31  and outlet end  33 . Inlet ends  27  and  31  are wider than outlet ends  29  and  33 . Valve body  21  and elastomeric sheath  23  have longitudinal bores running along the axis  39  of each part respectively. Inlet ends  27  and  31 , as well as corresponding outlet ends  29  and  33  are positioned along axis  39 . 
         [0039]    Valve body  21  has an inside conical space that tapers inward along the axis from inlet end  27 . Valve body  21  has inlet port  41  and outlet port  43  on the side for inlet channel  45  and outlet channel  47 . Valve body  21  has an inlet channel  45  toward the inlet end  27  that passes from the inlet conical space to the outside surface of the valve body  21 . Valve body  21  also has an outlet channel  47  toward the outlet end  29 . Outlet channel  47  transverses the wall of the valve body  21  from the outside surface at an angle to axis  39 . Elastomeric sheath  23  also has an inside conical space that tapers inward along the axis from inlet end  31 . Elastomeric sheath  23 , prior to placement over valve body  21 , has an inside diameter that is smaller than the outside diameter of valve body  21  at the inlet end. This difference in diameter is preferably greater at the inlet end than at the outlet end for providing greater sealing tension against the outside surface of the valve body at the inlet end than at the outlet end; and for providing greater fluid ejection ease at the outlet end. 
         [0040]    The thickness of elastomeric sheath  23  is preferably greater at the inlet end than at the outlet end for providing greater elastic restoring force against the outside surface of valve body  21  at the inlet end than at the outlet end. Greater elastomer thickness and/or tighter interference fit at the inlet end provides outward sealing direction and pressure forcing fluid through and out of the valve. The interference fit can be greater at both inlet end  27  and outlet end  29  than along the fluid flow path between inlet channel  45  and outlet channel  47  where the interference fit covering inlet port  41  is greater than the interference fit covering outlet port  43  and the fluid flow path in between. Thus, there may be different interference fits at the inlet end, the outlet end and the middle portion (between the inlet and outlet ends) of the assembled valve body, thereby forming an inlet interference fit, an outlet interference fit and a middle interference fit. Accordingly, in some embodiments, when the valve body and elastomeric sheath are assembled, they may form an outlet interference fit, an inlet interference fit and a middle interference fit, wherein the inlet interference fit is greater than the outlet interference fit and said outlet interference fit is greater than the middle interference fit. 
         [0041]    A greater interference fit at outlet end  29  axially above the lesser interference fit at outlet port  43  forces fluid through outlet channel  47  and out of the valve. Valve body  21  and elastomeric sheath  23  may also have flange sections  49  and  51  on their respective inlet ends. Flanges  49  and  51  can form a first surface facing in an axial direction toward outlet ends  29  and  33 . Valve body flange section  49  and elastomeric sheath flange section  51  can be joined to form a leak-free connection. Outlet channel  47  can have spiral grooves  73  along the axially extending walls to outlet end  29  for supporting and seating antimicrobial component silver coil  75  without impeding fluid flow. The sheath configuration options of a greater wall thickness at the inlet end of the valve than at the outlet end of the valve and/or a greater difference in the diameter of the valve body and the smaller diameter sheath at the inlet end of the valve than at the outlet end of the valve in  FIG. 1  can be applied to the embodiments that follow as well. The silver coil component can be configured in embodiments with a discrete outlet channel. The valve body and elastomeric sheath components can also be configured in a cylindrical design. 
         [0042]    Referring now to  FIGS. 1A-1C , outlet end  29  is configured without a discrete outlet channel inside valve body  21 . As shown in  FIG. 1A , fluid flows from inlet end  27  passed two inlet channels  45  through an outlet passageway along the exterior surface of valve body  21  and the interior surface of elastomeric sheath  23  to outlet end  29 . Elastomeric sheath  23  can form closure  61  in a variety of ways at outlet end  33 . In  FIG. 1A , closure  61  shows one slit  81 , but closure  61  may have a plurality of slits preferably of equal length and radial distance from the axis forming wedge shaped flaps of equal size extending axially over and outward from outlet end  29 . The inside surfaces of slits  81  expand to permit fluid flow out of the valve and contract to seal against adjacent and opposite inside surfaces. 
         [0043]    In  FIG. 1B , the valve body shown has a substantially circular recess  77  around the tip of the outlet end for seating conforming antimicrobial component silver cap  79 . Closure  61  has a ring shaped aperture  83  axially at or below the tip of the valve body at the outlet end for sealing partially over and against the outer radial portion of the outside surface of silver cap  79 . Fluid exits the valve from between the inside surface of aperture  83  and the outer radial portion of silver cap  79  onto the inner radial portion of silver cap  79 . 
         [0044]    In  FIG. 1C , closure  61  is sealed against the outside surface of silver cap  79 . Closure  61  has a plurality of substantially circular orifices  85  positioned over silver cap  79  at the outlet end. Closure  61  expands in response to fluid pressure and fluid exits the valve through orifices  85 . Aperture  83 , orifice  85  and sealing cap  79  of  FIGS. 1A-1C  can be designed in a number of shapes and sizes. Closure  61  can be any one of a number of known closures, including but not limited to a duckbill closure, a flattened hollow tube, which when under pressure will expand to permit fluid flow and contract once the pressure is relieved. 
         [0045]    The phrase “outer inlet valve body diameter” refers to the diameter of the valve body near the inlet end of the valve body. The phrase “outer outlet valve body diameter” refers to the diameter of the valve body near the outlet end of the valve body. As persons of ordinary skill will appreciate, the walls of the valve body will themselves have a thickness. The term “outer” is used to denoted that the measured diameters include the material that comprises the valve body itself. 
         [0046]    The phrase “inner inlet elastomeric sheath diameter” refers to the diameter of the elastomeric sheath&#39;s surface that will come into contact with the valve body at the point at which the outer inlet valve body diameter is measured. Similarly, the phrase “inner outlet elastomeric sheath diameter” refers to the diameter of the elastomeric sheath&#39;s surface that will come into contact with the valve body at the point at which the outer outlet valve body diameter is measured. In contrast to the term “outer” as used in the preceding paragraph, the term “inner” as used in the aforementioned phrases referring to the elastomeric sheath does not include the material of the sheath itself. 
         [0047]    Preferably, the difference between the outer inlet valve body diameter and inner inlet elastomeric sheath diameter is greater than the difference between the outer outlet valve body diameter and inner outlet elastomeric sheath diameter. The measurements are of course taken prior to assembly. When assembled and no fluid is being dispensed, the diameters of the aforementioned sheath regions are essentially the same as the diameters of the corresponding valve body regions. 
         [0048]    Referring now to  FIG. 2 , shown is a side cross sectional view of a valve assembly in an alternate embodiment that secures elastomeric sheath  23  in place over and radially around the outside surface of valve body  21  at the tapered end section of elastomeric sheath  23  between outlet port  43  and outlet end  33 . Elastomeric sheath  23  has an inward, O-ring like enlargement or protrusion  63  extending circumferentially around the inside surface of elastomeric sheath  23 . Valve body  21  has a conforming groove  65  along said circumference for receiving and seating protrusion  63  and for providing attaching means to affix elastomeric sheath  23  to valve body  21 . An O-ring can be substituted for protrusion  63 . 
         [0049]      FIG. 2A  shows an example of another alternate embodiment without a discrete outlet channel inside valve body  21 . In  FIG. 2A , valve body  21  extends axially outward from elastomeric sheath  23  and protrusion  63  at outlet end  29 . Valve body  21  has two spoon shaped indentations  71  extending axially under groove  65  to outlet end  29 . Fluid flows from inlet end  27  through two inlet channels  45  through an outlet passageway along the exterior surface of valve body  21  and the interior surface of elastomeric sheath  23  into valve body indentations  71  and exits under the line of sealing contact between protrusion  63  and groove  65  through outlet end  29 . Indentation  71  can be designed in a variety of shapes to control fluid flow and elastomeric sheath  23  can be designed to conform to, seal over, within or against indentation  71  to drive flowable materials through and out of the valve. 
         [0050]      FIG. 2B  shows a partial, perspective view of the valve assembly of  FIG. 2A . In  FIG. 2B , protrusion  63  has a circumferentially extending line of sealing contact against and below the tip of valve body  21  at outlet end  29 . Indentation  71  extends axially along the outside surface of valve body under the line of sealing contact and outward from elastomeric sheath  23  at outlet end  29 . 
         [0051]    Referring now to  FIG. 3 , shown is a cross section of one preferred embodiment according to the present invention. Inlet end  127  is the wider end of valve body  121 . Inlet end  127  leads to the inside conical space of valve body  121 . Valve body  121  has flange  149  on inlet end  127 . Inlet channel  145  passes in a generally perpendicular direction to the longitudinal axis of the valve body  121  from the inside conical space of valve body to the outside of valve body. Outlet end  129  is at the narrower end of valve body  121 . Outlet channel  147  leads from outlet end  129  for a short distance along the axis passing to the outside of valve body  121 . Inlet channel  145  and outlet channel  147  can be modified in number, size, location and design to facilitate the flow of a wide range of fluid viscosities and flow rates. Alternatively, outlet end  129  may be fitted with a drop meter; a hypodermic needle or a nozzle for providing the desired form for the fluid being dispensed including a spray or a stream; or a closure device. 
         [0052]    The valve body  121  fits inside of elastomeric sheath  123 . Like valve body  121 , elastomeric sheath  123  is conically shaped with a flange section  151  at its wider end. Elastomeric sheath  123  also has a tapered end section  133  to match with the tapered end section  129  of valve body  121 . Elastomeric sheath  123 , prior to placement over valve body  121 , has an inside diameter smaller than the outside diameter of valve body  121  at inlet end  131 . This difference in the inside diameter of elastomeric sheath  123  to the outside diameter of valve body  121  is preferably greater at inlet end  131  than at outlet end  133 . This provides greater sealing tension against the outside surface of the valve body at inlet end  131 . The elastomeric sheath  123  then passes more easily over outlet end  129  of valve body  121  before stretching to fit tightly around the inlet end  127  of valve body  121 . Preferably elastomeric sheath  123  has a greater thickness at inlet end  131  than at the tapered outlet end section  133 . This provides greater elastic restoring force at the inlet end than the outlet end and greater fluid ejection ease through and out of the valve. 
         [0053]    Both valve body  121  and elastomeric sheath  123  fit inside enclosing sleeve  125 . The inside surface of enclosing sleeve  125  is preferably conical in shape. Enclosing sleeve  125  has a wider inlet end  135  than outlet end  137  positioned along the longitudinal axis. Enclosing sleeve  125  also has a flange section  153  with an increased diameter to contain valve body flange section  149 . On the inside of the increased diameter section  153  is a radially inward extending shoulder that secures elastomeric sheath flange section  151 . Enclosing sleeve  125  contains expansion chamber  155  in the inside of conical section  157 . This space allows elastomeric sheath  123  to expand under fluid pressure coming from inlet channel  145 . Enclosing sleeve  125  also features venting means  159  to relieve air pressure against the outside surface of elastomeric sheath  123  within expansion chamber  155 . Enclosing sleeve  125  can form a seal with elastomeric sheath  123  and valve body  121  at inlet end  127  and outlet end  129  allowing elastomeric sheath  123  to remain in tight contact with valve body  121 . The preferred method of directing fluid flow is through lines of sealing contact with enclosing sleeve  125  along the outside surface of elastomeric sheath  123 . 
         [0054]      FIG. 4  shows an example of another alternate embodiment of the present invention. In  FIG. 4 , outlet end  129  is shown without a discrete outlet channel inside valve body  121 . Fluid flows from inlet end  127  along the exterior surface of valve body  121  and the interior surface of elastomeric sheath  123  to outlet end  129 . Enclosing sleeve  125  provides a line of sealing contact extending in the axial direction against the outside surface of elastomeric sheath  123  that directs the fluid through an outlet passageway along the exterior surface of valve body  121  and elastomeric sheath  123  forms closure  161  for such a passageway. The line of sealing contact limits the area of chamber  155  for the expansion of elastomeric sheath  123  to direct a fluid flow path along, through and out of valve body  121 . Closure  161  can extend axially outward from outlet end  129 . Closure  161  can be any one of a number of known closures, such as a duckbill closure, a flattened hollow elastomeric tube, which when under pressure will expand to permit fluid flow and contract once the pressure is relieved. 
         [0055]      FIG. 4A  shows an example of another alternate embodiment without a discrete outlet channel inside valve body  121 . In  FIG. 4A , valve body  121  extends axially outward from elastomeric sheath  123  and enclosing sleeve  125  at outlet end  129 . Enclosing sleeve  125  provides a line of sealing contact at outlet end  129  extending circumferentially around and against elastomeric sheath  123 . Valve body  121  has two spoon shaped indentations  171  extending axially from below the line of sealing contact to outlet end  129 . Fluid flows from inlet end  127  passed two inlet channels  145  through an outlet passageway along the exterior surface of valve body  121  and the interior surface of elastomeric sheath  123  into valve body indentations  171  and exits under the line of sealing contact between elastomeric sheath  123  and valve body  121  through outlet end  129 . Indentation  171  can be designed in a variety of shapes to control fluid flow and elastomeric sheath  123  can be designed to conform to, seal over, within or against indentation  171  to drive flowable materials through and out of the valve. 
         [0056]      FIG. 4B  shows a partial perspective view of the valve assembly of  FIG. 4A . In  FIG. 4B , enclosing sleeve  125  has a circumferentially extending line of sealing contact below the tip of valve body  121  at outlet end  129 . Indentation  171  extends axially along the outside surface of valve body  121  under the line of sealing contact and outward from enclosing sleeve  125  at outlet end  129  for delivering viscous materials out of the valve. 
         [0057]    Referring now to  FIG. 5 , shown is a cross sectional view of another embodiment according to the present invention. Inlet end  227  is the narrower end of conical valve body  221 . Outlet end  229  is at the wider end of the valve body. The valve body  221  has tubular section  267  extending axially from inlet end  227 . Tapered end section  269  of valve body  221  extends radially outward from tubular section  267  of valve body  221 . Valve body  221  has flange  249  on outlet end  229 . Inlet end  227  leads to the inside conical space of valve body  221 . Inlet channel  245  passes in a generally perpendicular direction to axis  39  of valve body  221  from the inside conical space of valve body  221  to the outside of valve body  221 . Outlet channel  247  leads from outlet end  229  for a short distance along the axis passing to the outside of valve body  221 . 
         [0058]    The valve body  221  fits inside of elastomeric sheath  223 . Like valve body  221 , elastomeric sheath  223  is conically shaped with a flange section  251  at its wider end. Elastomeric sheath  223  has a tapered end section  231  to match with the tapered end section  269  of valve body  221 . Elastomeric sheath  223  also has annular shoulder  265  extending radially inward and against the outside surface of tapered end section  269  of valve body  221  and around tubular section  267  of valve body  221 . Elastomeric sheath  223 , prior to placement over valve body  221 , has an inside diameter smaller than the outside diameter of valve body  221  at inlet end  231 . This difference in the inside diameter of elastomeric sheath  223  to the outside diameter of valve body  221  is preferably greater at inlet end  231  than at outlet end  233 . This provides greater sealing tension against the outside surface of the valve body at inlet end  231 . The elastomeric sheath  223  then passes more easily over inlet end  227  of valve body  221  before stretching to fit tightly around the outlet end  229  of valve body  221 . Preferably elastomeric sheath  223  has a greater thickness at inlet end  231  than at the wider outlet end section  233 . This provides greater elastic restoring force at the inlet end than the outlet end and greater fluid ejection ease through and out of the valve. 
         [0059]    Both valve body  221  and elastomeric sheath  223  fit inside enclosing sleeve  225 . The inside surface of enclosing sleeve  225  is preferably conical in shape. Enclosing sleeve  225  has annular shoulder  235  extending radially inward and sealing against the outside surface of conforming annular shoulder  265  of elastomeric sheath  223  and around tubular section  267  of valve body  221 . Enclosing sleeve  225  also has a flange section  253  with an increased diameter to contain valve body flange section  249 . On the inside of the increased diameter section  253  is a radially inward extending shoulder that secures elastomeric sheath flange section  251 . Enclosing sleeve  225  contains expansion chamber  255  in the inside of conical section  257 . This space allows elastomeric sheath  223  to expand under fluid pressure coming from inlet channel  245 . Enclosing sleeve  225  also features venting means  259  to relieve air pressure against the outside surface of elastomeric sheath  223  within expansion chamber  255 . Enclosing sleeve  225  can form a seal with elastomeric sheath  223  and valve body  221  at inlet end  227  and outlet end  229  allowing elastomeric sheath  223  to remain in tight contact with valve body  221 . The preferred method of directing fluid flow is through lines of sealing contact with enclosing sleeve  225  along the outside surface of elastomeric sheath  223 . 
         [0060]      FIG. 6  shows an example in another embodiment of the present invention. Inlet channel  245  and outlet channel  247  are aligned on the same side of valve body  221  to shorten the fluid flow path. Inside conical section  257  of enclosing sleeve  225  has a line of sealing contact against the outside surface of elastomeric sheath  223  extending in the axial direction from inlet end  227  to outlet end  229  180° opposite inlet channel  245  and outlet channel  247  preventing a spiral fluid flow path along the outside surface of valve body  221 . The line of sealing contact limits the area of chamber  255  for the expansion of elastomeric sheath  223  to provide a direct fluid flow path along, through and out of valve body  221 . 
         [0061]      FIG. 7  shows an example in another embodiment of the present invention. Inlet channel  245  and outlet channel  247  are aligned on opposite sides of valve body  221  to lengthen the fluid flow path shown in  FIG. 6 . Inside conical section  257  of enclosing sleeve  225  has a line of sealing contact against the outside surface of elastomeric sheath  223  extending diagonally across valve body  221  in the axial direction from inlet end  227  to outlet end  229  preventing a spiral fluid flow path along the outside surface of valve body  221 . The line of sealing contact limits the area of chamber  255  for the expansion of elastomeric sheath  223  to provide a direct fluid flow path along, through and out of valve body  221 . 
         [0062]    Inlet channel  245  and outlet channel  247  can be modified in number, size, location and design to facilitate the flow of a wide range of fluid viscosities and flow rates. Delivery of more viscous fluid at higher flow rates can be produced by increasing the number and/or the diameter of inlet and outlet channels. The location of inlet and outlet channels can also be used to facilitate flow rate. For example, the aligned port configuration of inlet channel  245  and outlet channel  247  shown in  FIG. 6  has a shorter, more direct fluid flow path preferred for delivery of more viscous fluids than the 180° opposed port configuration shown in  FIG. 7 . 
         [0063]    Referring now to  FIG. 8  and to the corresponding features in  FIG. 5 , enclosing sleeve  125  can provide protective cover and resistance against forces from outside inlet channel  145  and outlet channel  147  and therefore ensure that flowable materials pass through and out of the valve without backflow of air and contaminants into the container. Enclosing sleeve  125  can be attached to valve body flange section  149  via any attaching means, including but not limited to, snap fitting, press fitting, heat sealing or welding. Any other method for joining parts to obtain a leak free connection may be used. 
         [0064]    Valve body  121 , elastomeric sheath  123  and enclosing sleeve  125  are assembled to make a conical one-way valve. The valve is then attached to the collapsible container to form the complete fluid dispensing system. Fluid flows from the container into inlet end  127  and passes into the conical space of valve body  121 . As more fluid enters this space, the pressure increases and fluid is forced through inlet channel  145 . Once the pressure is sufficient, elastomeric sheath  123  deforms and allows fluid in to expansion chamber  155 . As expansion chamber  155  fills, the fluid flows along the outside surface of valve body  121  before it passes back into valve body  121  through outlet channel  147  and finally out of the valve through outlet end  129 . Reduction of fluid pressure from inlet end  127  sufficient to enable elastomeric sheath to collapse and reseal first against the outside surface of inlet channel  145 , provides the outward sealing direction and force against the outside surface of valve body  121  to drive all fluid within expansion chamber  155  out of the valve through outlet channel  147  and outlet end  129 . Backflow and therefore contamination is prevented by the greater sealing tension and elastic restoring force of elastomeric sheath  123  at the inlet end than at the outlet end. 
         [0065]    All three components, namely valve body  121 , elastomeric sheath  123  and enclosing sleeve  125  may contain and/or be coated with an anti-microbial agent to prevent contamination of sterile fluids. An inert, non-elutable anti-microbial agent is preferred. Likewise, all three components may be composed of materials that are stable to solutions under a broad pH range and resistant to degradation under exposure to a wide range of organic and aqueous solvents. 
         [0066]    Within ranges of interference fit, increased sealing tension may be expected with greater differences in valve body diameter to undersized sheaths. Sheaths with a greater wall thickness may be expected to provide more elastic restoring force. Sheaths with a smaller wall thickness may be expected to provide greater ejection ease. Preferably the wall thickness of the sheath is in the range of 8/1000″ to 35/1000″. The durometer is preferably in the range of 25-60 (A). The wall thickness and durometer of the sheath can be adjusted for optimal sealing and ejection ease. A wall thickness ratio of at least 2 to 1 from inlet to outlet is preferred where the difference in diameter of the valve body and the smaller diameter sheath is not reduced from inlet end to outlet end. The preferred range of sheath inner diameters comprising the interference fit is 0.5 to 0.9 times the outer diameter of the valve body. The most preferred sheath inner diameter comprising the interference fit is approximately 0.75 times (0.70-0.80 times) the outer diameter of the valve body at the inlet end. 
         [0067]    Tapered sheath wall thickness and/or reduced interference fit is configured to provide greater sheath compression at the inlet end than at the outlet end, as well as to overcome pressure gradient force, which is apt to be greater at the narrower end in a conical valve design. Inlet and outlet ports and channels can be aligned, staggered and configured in number, placement and size to achieve desired fluid flow paths and flow rates, as well as to enhance sealing effectiveness and facilitate the prevention of fluid backflow. Inlet port(s) and outlet port(s)/passageway(s) may be configured at a predetermined fluid flow path distance for effective sealing of the valve and prevention of backflow. The length of the flow path between inlet port(s) and outlet port(s)/passageway(s) is preferably at least one-half inch, and in some embodiments preferably 2 to 2.5 times the length of the diameter of the valve body at the wider end. The length of the flow path can be equal to the wider valve body diameter in shorter, low profile valves when configured with greater sheath wall thicknesses and larger diameter ports. Low profile valves can provide the same effective sealing capabilities, backflow prevention and fluid ejection ease as a longer valve with a thinner elastomeric sheath. 
         [0068]    Appropriate valve materials may depend on the nature of the fluid and the application. Preferable materials for the valve body and elastomeric sheath have low absorbance, high adhesive surface characteristics that form bonds that maintain a quick and firm sealing tension. Preferred materials for the elastomeric sheath are silicone, polystyrene butadiene, rubber latex and butyl rubber. Preferred materials for the valve body are polymethacrylate and polysulfone. Elastomeric materials with a durometer of 70 (A) or higher may be used as well. Also, Teflon valve bodies can be made effective sealing agents when configured with greater sheath wall thicknesses although the material does not have a preferred sealing surface. Some materials with low adhesive surface characteristics can be treated to increase adhesive bonds to elastomeric materials. For example, polypropylene can be heat treated to enhance sealing effectiveness in applications requiring solvent resistance. 
         [0069]    Previous inventions in this area have been used to protect chemicals, medicines, personal hygiene products and other flowable materials susceptible to contaminations by atmospheric gases and microorganisms. The designs of the various embodiments of the present invention, with their enhanced ease of manufacturing and assembly will decrease the cost of current applications of one way valves and extend the use of one way valves to previously prohibited applications. For example, in embodiments that contain a conical shape of the valve in a 180° opposed port configuration, the system allows the fluid to flow through the valve in a spiral fashion along a path that can be greater than the length of the valve body. This enables the valve body to be smaller, cheaper and easier to assemble without functional sacrifice. 
         [0070]    While the present invention has been described with reference to one or more preferred embodiments, such embodiments are merely exemplary and are not intended to be limiting or represent an exhaustive enumeration of all aspects of the invention. The scope of the invention, therefore, shall be defined solely by claims not provided herein. Further, it will be apparent to those skilled in the art that numerous changes may be made in such details without departing from the spirit and the principles of the invention. It should be appreciated that the present invention is capable of being embodied in cylindrically shaped, wedge shaped or other forms without departing from its essential characteristics.