U.S. patent application number 11/021093 was filed with the patent office on 2005-07-14 for anti-drip anti-foaming fluid dispensing system.
Invention is credited to Bach, David T..
Application Number | 20050150911 11/021093 |
Document ID | / |
Family ID | 34742399 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050150911 |
Kind Code |
A1 |
Bach, David T. |
July 14, 2005 |
Anti-drip anti-foaming fluid dispensing system
Abstract
A system for dispensing exact quantities of fluid into
containers without dripping or foaming can be made from the
combination of a controllable pump, a tube (preferably
hydrophobic), and a nozzle usually made of elastomeric material
with an orifice or slit such a duck bill valves commercially
available. Forward pressure causes the slit to open, while elastic
force causes it to close when pumping stops. An alternative
embodiment is to use slits backed by small diameter screen to
achieve a back pressure.
Inventors: |
Bach, David T.; (Ellicott
City, MD) |
Correspondence
Address: |
Clifford Kraft
320 Robin Hill Dr.
Naperville
IL
60540
US
|
Family ID: |
34742399 |
Appl. No.: |
11/021093 |
Filed: |
December 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60532307 |
Dec 23, 2003 |
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Current U.S.
Class: |
222/209 |
Current CPC
Class: |
B67D 1/10 20130101; B67D
1/108 20130101; B67D 1/1256 20130101 |
Class at
Publication: |
222/209 |
International
Class: |
B65D 037/00 |
Claims
I claim:
1. A no-drip, anti-foaming fluid dispensing system comprising: a
fluid pump supplying a forward fluid pressure; a delivery tube
fluidly coupled to said pump for delivering said fluid into a fluid
container; an elastomeric tip on said delivery tube containing at
least one exit orifice, said exit orifice expanding in response to
said forward fluid pressure and contracting when said forward fluid
pressure is removed.
2. The fluid dispensing system of claim 1 wherein said fluid pump
is a positive displacement linear pump.
3. The fluid dispensing system of claim 1 wherein said fluid pump
is a peristaltic pump.
4. The fluid dispensing system of claim 1 wherein said elastomeric
tip is a duck bill valve.
5. The fluid dispensing system of claim 1 wherein said elastomeric
tip has a plurality of orifices.
6. The fluid dispensing system of claim 1 further comprising said
pump also supplying back pressure after a predetermined quantity of
said fluid is dispensed.
7. The fluid dispensing system of claim 4 wherein said duck bill
valve is silicone.
8. The fluid dispensing system of claim 1 wherein said delivery
tube is a hydrophobic material.
9. A no-drip, anti-foaming fluid dispensing system comprising: a
fluid pump supplying a forward fluid pressure; a coupling tube
fluidly coupled to said pump for delivering said fluid into a fluid
container; a dispensing tip on said coupling tube containing at
least one exit orifice; a screen covering said exit orifice, said
polymer screen preventing drip through when said forward fluid
pressure is removed.
10. The fluid dispensing system of claim 9 wherein said exit
orifice is elongated along the axis of said coupling tube.
11. The fluid dispensing system of claim 9 further comprising a
second screen covering said exit orifice.
12. The fluid dispensing system of claim 9 wherein said screen is a
polymer.
13. The fluid dispensing system of claim 9 wherein said pump is a
positive displacement linear pump.
14. The fluid dispensing system of claim 9 wherein said pump is a
peristaltic pump.
15. A method of dispensing a predetermined quantity of fluid into a
container without drip or foaming comprising the steps of: causing
a fluid pump to move said predetermined quantity of fluid from a
reservoir into a delivery tube, said delivery tube having at least
one exit orifice, said exit orifice containing a means for causing
backpressure on said flow, wherein a forward pressure from said
pump overcomes this backpressure to allow said predetermined
quantity of fluid to exit said orifice; allowing said backpressure
to keep any remaining fluid in said tube after said predetermined
quantity of fluid has been dispensed.
16. The method of claim 15 wherein said means for causing
backpressure is a duck bill valve.
17. The method of claim 15 wherein said means for causing
backpressure is a screen.
18. The method of claim 15 wherein said delivery tube is
hydrophobic.
19. The method of claim 15 wherein said pump is a linear
displacement piston driven pump.
20. The method of claim 15 wherein said pump is a peristaltic pump.
Description
[0001] This application is related to and claims priority from U.S.
Provisional patent application No. 60/532,307 filed Dec. 23, 2003.
Application 60/532,307 is hereby incorporated by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] This invention relates generally to the field of precision
fluid dispensing and more specifically to a fluid dispensing system
the is prevents dripping and foaming.
[0004] 2. Description of the Prior Art
[0005] Many applications in the field of bio-science and medicine
require the precise dispensing of a quantity of fluid into a
particular container. There is no tolerance for dripping. Also,
some liquids tend to foam if dispensed too rapidly through a
standard nozzle or through a tube with too small an inside
diameter. For example, an application might require the precision
dispensing of 125 ml of a particular liquid (like a salt solution)
into a vessel holding exactly 125 ml. Usually such a fill needs to
take place very rapidly (within a second or two). No liquid can be
lost through dripping.
[0006] What is badly needed is a system and method for making fast
fluid dispenses into containers designed to contain a precise
amount of fluid without dripping or foaming.
SUMMARY OF THE INVENTION
[0007] The present invention relates to a non-drip, anti-foaming
fluid dispensing system that can contain a fluid pump that supplies
a forward fluid pressure, a coupling tube (preferably of
hydrophobic material) that is coupled to the pump for delivering
fluid into a fluid container, and an elastomeric tip on the
coupling tube that can contain at least one exit orifice. The exit
orifice can generally respond in response to the forward fluid
pressure and contract when the forward fluid pressure is removed.
This contraction prevents air from entering the delivery tube and
causing dripping.
[0008] The fluid pump can be a positive displacement linear pump or
a peristaltic pump or any other type of fluid pump causing a
forward pressure on a fluid. In particular, the tip can be a duck
bill valve with one or more openings or orifices. The pump can
optionally supply a back pressure or suck-back after a
predetermined amount of fluid has been dispensed.
DESCRIPTION OF THE FIGURES
[0009] FIG. 1 shows a schematic of an embodiment of the present
invention.
[0010] FIG. 2A shows a duck bill valve on the end of a TEFLON
tube.
[0011] FIG. 2B shows a duck bill valve on the of a steel tube.
[0012] FIG. 3 shows various cut patterns that can be used with a
nozzle.
[0013] FIG. 4. shows an embodiment of a nozzle with vertical exit
slits.
[0014] Several drawings and illustrations have been presented to
aid in the understanding of the present invention. The scope of the
present invention is not limited to the figures.
DESCRIPTION OF THE INVENTION
[0015] FIG. 1 shows a schematic of an embodiment of the present
invention. A pump 1, which can be a positive linear displacement
pump, a peristaltic pump, or other controllable pump drives a
delivery tube 2 that ends in an end control device or nozzle 3. The
unique characteristics of the entire system allow a precise amount
of fluid to be dispensed without dripping or foaming in to a
container 4.
[0016] FIGS. 2A and 2B show a tube with a duck bill valve 5 as a
nozzle or tip. Here a tube of 1/2 inch ID or larger can be attached
to a duck bill valve of the type sold commercially. The tube 2
shown in FIGS. 1 and 2 can be made of TEFLON. This material can be
chosen to make the tube hydrophobic. While it is not critical that
all tubes be of a hydrophobic material, much better results are
generally achieved when hydrophobic materials are used.
[0017] The diameter of the tube usually must be chosen to match the
required fill time against the volume of fluid being dispensed. For
the example where a 125 ml container is to be filled with exactly
125 ml of fluid in 2 seconds or less, the tubing must have an ID of
greater than 1/2 inch. The problem with large tubes such as this is
that after the initial fill, residual fluid on the inside of the
tube drips causing the fill volume to be exceeded. The surface
tension on such large tubes is not sufficient to stop air from
flowing up the tube, and the solution continuing to flow down the
tube.
[0018] A small nozzle must generally be used on the end of the tube
to stop this air flow and drip. An ideal nozzle is one made of an
elastomeric material such as rubber or silicone with a small
orifice 6. Such a material expands to expel the initial flow under
forward pressure from the pump, but then contracts to prevent the
entry of air and any subsequent drip. In addition, some pumps can
be arranged to create a suck-back where the pump reverses direction
and causes a negative pressure on the fluid. A positive
displacement linear piston pump is particularly suited for
this.
[0019] An ideal nozzle is a duck bill valve that can be purchased
commercially. FIG. 2A shows such a valve 5 on the end of a TEFLON
tube, while FIG. 2B shows such a valve on a steel tube. The duck
bill opens when the flow is pumped forward and closes when pumping
is stopped. The contraction of the rubber slit helps prevent any
further flow that could result in a drip. Suck-back can also be
used to assist in fluid stoppage and in duck bill closure. The duck
bill reduces the apparent open area of the nozzle so that fluid
surface tension is enough to block the air/fluid transfer up the
larger diameter tube.
[0020] The duck bill nozzle 5 shown in FIGS. 2A and 2B opens for
each dispense by an amount based on the fluid volume and the
dispensing velocity. Using such a nozzle, it is possible to large
tubes and deliver large quantities of fluid exactly. Using such a
nozzle (or smaller versions of it) with smaller tubes allows
systems that precisely deliver very small volumes. In fact, a
single tube/nozzle combination can accurately deliver both very
large and very small quantities without drip or foaming.
[0021] FIG. 2B shows a steel tube 7 with a duck bill nozzle. The
tube can be any size including 1/2 stainless steel. A possible
nozzle 5 is the Vernay VL4513-103 duck bill. This silicon duck bill
can be configured either as a single cut or with multiple cuts as
shown in FIG. 3.
[0022] An alternative embodiment of the present invention is shown
in FIG. 4. Here a nozzle head 8 can be made from a part of the
tubing 2 equipped with cuts or slits 9 backed by a screen. It is
preferred to use several axial cuts around the circumference as
shown in FIG. 4 to create a side-port nozzle. Each cut can be
backed by filter screens or any other device that will cause a
slight back pressure. The side ports 9 provide increased fluid exit
area that slows the output stream velocity. The side ports can be
made vertical to also aid in keeping the exit velocity low and
allow for a more gradual pressure drop from the top to the bottom
of each slight. This results in a slightly downward flow angle out
of the slot. In generally, the screen prevents dripping. A
preferred screen material is around 75 to 105 micron polypropylene
screen. Each screen provides a slight amount of back pressure so
that fluid in the relatively short nozzle does not drip. It is
necessary to keep the fluid column behind the screen from becoming
too large or the static pressure behind the screen can still cause
dripping.
[0023] A duck bill can be combined with the nozzle shown in FIG. 4.
This arrangement allows the length of the fluid column to be
increased above the duck bill. The duck bill provides an additional
pressure to the fluid in a tube or reservoir above the side ports.
In addition to a duck bill, multiple screens can be used (not
necessarily of the same size) to provide additional pressure
drop.
[0024] Several illustrations and descriptions have been provided to
aid in understanding of the present invention. One skilled in the
art will realize that many changes and variations are possible.
These changes and variations are within the scope of the present
invention.
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