Fluid handling – Processes
Reexamination Certificate
2001-10-03
2004-07-27
Krishnamurthy, Ramesh (Department: 3753)
Fluid handling
Processes
C137S846000, C137S853000, C222S001000, C222S490000, C222S494000
Reexamination Certificate
active
06766816
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a system for dispensing fluids. More specifically, the present invention relates to a one-way valve assembly for dispensing fluid from a collapsible container. The valve assembly of the present invention also prevents backflow into the container prior to, during and following distribution of the fluid, thereby keeping unwanted items such as contaminants out of the container.
BACKGROUND OF THE PRESENT INVENTION
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. Generally, when fluids are dispensed from a valve assembly, the volume of product delivered from the valve assembly 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 contaminants in the air such as microorganisms, atmospheric gases, moisture and dust particles. The quality, potency, safety and/or sterility of the remaining product can be compromised by the air and potential contaminants within.
The present invention delivers fluid under positive pressure through a one-way valve from a container that collapses in proportion to the amount of product dispensed. Consequently, air does not enter the dispensing system.
The concept of a one-way valve assembly is not new. One-way valves are used extensively throughout the medical field in complex medical device machinery to dispense flowable products. One-way valves are also being used in aerosol dispensers to dispense flowable products. However, the need for a contamination-safe, propellant-free one-way valve that can easily be manufactured and assembled has long been apparent. As the medical field continues to grow, the need to dispense multiple doses of sterile fluids during surgery, diagnostic testing, ophthalmology and other areas without fear of contamination continues to grow as well. Thus, there exists a need for creating a collapsible dispensing system that is simple to manufacture and assemble for dispensing multiple doses of sterile fluids.
Several one-way valves contain cylindrical cores encompassed by an elastic cylindrical sheath. The core typically has an entrance tube leading to one area of the sheath, and an exit tube leading away from another area of the sheath. The entrance and exit tubes, while enclosed by the sheath, do not interconnect. To dispense liquid, one would apply pressure to expand the sheath, allowing liquid to pass from the entrance tube to the exit tube. Upon release of that pressure, the sheath would contract, thereby sealing the valve and preventing backflow into the container.
For example, U.S. Pat. Nos. RE 34,243; 5,836,484; 5,279,330; 5,305,783; 5,305,786; 5,080,138; 5,080,139; and 5,092,855 all disclose cylindrical one way valves for dispensing liquids and eliminating backflow of unwanted materials. Some of these, such as U.S. Pat. No. 5,080,138, have an excessive number of parts. All of these, particularly the disc shaped valves in U.S. Pat. Nos. 5,080,139 and 5,279,330, are unnecessarily difficult to assemble.
Referring to
FIG. 1
, shown is a dispensing valve assembly for dispensing liquids of different consistencies according to U.S. Pat. No. RE 34,243. Shown is valve assembly
11
containing five pieces. Valve assembly
11
is mounted on flexible container
13
such that fluid will be dispensed when container
13
is compressed. Valve assembly
11
is constructed by stretching sheath
15
over the outside of valve body (not pictured). Sheath
15
is sealed on the outside surface of the valve body by O-rings
17
.
The five-piece design disclosed in U.S. Pat. No. RE 34,243, and shown in
FIG. 1
, has several disadvantages. First, the five-piece design makes the unit costly to manufacture, as at least four distinct units must be manufactured, and each unit must be constructed with precision. The existence of such a five-piece apparatus also necessarily indicates a level of complexity when assembling. Sheath
15
must be stretched over valve body (not pictured) and then secured in place over O-rings
17
. This process is difficult to accomplish.
Referring now to
FIG. 2
, shown is the valve assembly of U.S. Pat. No. 5,305,783. Shown is valve body
21
covered by elastomeric sleeve
23
with O-ring like enlargements
25
at the each end. Elastomeric sleeve
23
is secured to valve body
21
by O-ring like enlargements
25
by forming a seal at reduced diameter ends
27
of valve body
21
. This design renders assembly of such a valve difficult.
To illustrate, the steps required to attach elastomeric sleeve
23
onto valve body
21
are shown in
FIGS. 3A-3D
. Elastomeric sleeve
23
is first formed on molding core pin
29
as shown in FIG.
3
A. Elastomeric sleeve
23
must then be rolled up on itself on molding core pin
29
as depicted in FIG.
3
B. Molding core pin
29
is then removed as depicted in FIG.
3
C. Elastomeric sleeve
23
is then placed on valve body
21
with O-ring like enlargement
25
a
and elastomeric sleeve
23
is secured to reduced diameter end section
27
of valve body
21
as shown in FIG.
3
D. The assembly is completed when elastomeric sleeve
23
is unrolled and O-ring like enlargement
25
b
secures the reduced diameter end section
27
of the valve body
21
as resulting in the configuration shown in FIG.
2
.
This process could be done manually but it would be time consuming. Alternatively, the assembly process could be automated but would involve an unacceptable rate of failure resulting in increased expense.
Referring now to
FIG. 4
, shown is a valve assembly according to U.S. Pat. No. 5,092,855. Sheath
31
has O-rings
33
at both ends of valve body
35
. O-rings
33
secure sheath
31
to valve body
35
when O-rings
33
seat into annular grooves formed on the outside of valve body
35
. Sheath
31
is further secured by enclosing sleeve
37
which fits over sheath
31
and valve body
35
and ensures sheath
31
and valve body
35
are sealed. Once again, sheath
31
must be stretched over valve body
35
rendering assembly of such a valve difficult and costly to manufacture on a commercial scale.
Referring next to
FIG. 5
, shown is a valve assembly according to U.S. Pat. No. 5,305,786. As shown, valve body
41
, elastomeric member
43
and cover member
45
are cylindrical. This cylindrical design is a disadvantage during assembly. For the valve assembly to operate as described, the diameter of cylindrical section
47
of valve body
41
must be only slightly smaller than the diameter of cylindrical section
49
of cover member
45
. Therefore, insertion of valve body
41
into elastomeric member
43
and subsequently into cover member
45
can tolerate only slight deviations in any direction perpendicular to the axis of the valve.
Referring again to
FIG. 1
, to assemble a valve assembly such as the one depicted, sheath
15
is typically rolled axially onto a mandrel or support pin and then carefully rolled up from one end toward the other in preparation for placement on valve body (not pictured). Alternatively, sheath
15
can be fitted on arms for lateral expansion with compressed air while the valve body is inserted into sheath
15
. In either case, assembly, whether performed manually or by complex machinery, is slow, cumbersome, and sometimes ineffective. Another disadvantage with the design depicted in
FIG. 1
is that sheath valve is cylindrical, thereby requiring the inside diameter of the sheath to be marginally smaller than the outside diameter of the valve body in order to maintain the necessary sealing tension of sheath
15
against the valve body. As stated above, the cylindrical design necessarily makes the valve assembly of
FIG. 1
difficult and costly to manufacture and assemble.
Referring now to
FIG. 6
, shown is a multiple dose dispensing system according to U.S. Pat. No. 5,836,484. Sh
Hunter Group, Inc.
Kalow & Springut LLP
Krishnamurthy Ramesh
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