U.S. patent application number 10/539664 was filed with the patent office on 2006-11-09 for fluid metering with a disposable membrane type pump unit.
Invention is credited to Hugh Christopher Bramley, John Hunter, Richard John Nighy.
Application Number | 20060251533 10/539664 |
Document ID | / |
Family ID | 34809877 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060251533 |
Kind Code |
A1 |
Nighy; Richard John ; et
al. |
November 9, 2006 |
Fluid metering with a disposable membrane type pump unit
Abstract
A disposable pump unit (100) for receiving and metering a
predetermined volume of fluid has a body with a surface at which
opens the mouth of a cavity (7) formed in the body. An inlet port
(4) for the fluid opens at the surface adjacent to the mouth of the
cavity (7) and a plurality of outlets (9) are provided in the
cavity (7) that open to a fluid flow passageway extending through
the body and connecting the cavity (7) to an outlet port (10). A
flexible membrane (8) overlies the cavity (7), the inlet port (4)
and the outlet port (10) and is sealingly secured at its periphery
to the surface. A re-usatile pump actuating unit (200) is
co-operable with the pump unit (100) to position the membrane (8)
between the cavity (7) in the pump unit (100) and a matching cavity
(21) in the actuating unit (200). The membrane (8) is towards and
away from the cavity (7) by connecting the cavity (21) to a source
of positive and negative fluid pressure via a port (18). The
actuating unit (200) has an armature (19) operable to displace the
membrane (8) to close the inlet port (4) when the outlet port (10)
is open and an armature (20) operable to displace the membrane (8)
to close the outlet port (10) when the inlet port (4) is open. In
use, the pump unit (100) draws fluid into the cavity (7) when the
inlet port (4) is open and a negative fluid pressure is applied to
the chamber (21) and pumps the fluid out of the cavity (7), when
the inlet port (4) is closed and a positive fluid pressure is
applied to the chamber (21).
Inventors: |
Nighy; Richard John;
(Stratford on Avon, GB) ; Hunter; John; (Circle
Rogers, MN) ; Bramley; Hugh Christopher;
(Staffordshire, GB) |
Correspondence
Address: |
PYLE & PIONTEK
221 N. LASALLE STREET,
SUITE 2036
CHICAGO
IL
60601
US
|
Family ID: |
34809877 |
Appl. No.: |
10/539664 |
Filed: |
January 21, 2005 |
PCT Filed: |
January 21, 2005 |
PCT NO: |
PCT/GB05/00201 |
371 Date: |
May 15, 2006 |
Current U.S.
Class: |
417/479 |
Current CPC
Class: |
F04B 43/0736
20130101 |
Class at
Publication: |
417/479 |
International
Class: |
F04B 43/00 20060101
F04B043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 21, 2004 |
GB |
0401198.7 |
Apr 24, 2004 |
GB |
0409149.2 |
Claims
1-30. (canceled)
31. A disposable pump unit for receiving and metering a
predetermined volume of fluid, the pump comprising a body, the body
having a surface at which opens the mouth of a cavity formed in the
body, an inlet port for connection with a reservoir of fluid and
opening at the body surface adjacent to the mouth of the cavity
whereby, when the inlet port is open when the pump is being filled
with fluid from the reservoir, fluid can flow from the inlet port
into the cavity via the mouth thereof, an outlet port for the fluid
and opening at the body surface, and a fluid flow passageway
extending through the body and connecting the cavity to the outlet
port; and flexible membrane means sealingly secured at its
periphery to the body surface and having a first portion overlying
the cavity and the inlet port and a second portion overlying the
outlet port, the flexible membrane means whereat it overlies the
inlet and outlet ports being moveable against the ports to close
the ports.
32. A disposable pump unit according to claim 31, wherein the first
and second portions of the flexible membrane means together
comprise an integral flexible membrane.
33. A disposable pump unit according to claim 31, wherein said
first and second portions of the flexible membrane means are
separate from one another.
34. A disposable pump unit according to claim 31, wherein the first
portion of the flexible membrane means is substantially
non-stretchable and is pre-formed in part to a shape substantially
similar to the shape of a surface of the pump cavity such that,
when the pump is operated to pump a metered volume of fluid through
the outlet port, the pre-formed part of the flexible membrane means
can be urged by an actuating fluid into the pump cavity and into
contact with substantially the whole surface of the cavity to force
from the cavity and through the passageway and outlet port
substantially all of the fluid that flowed from the reservoir into
the cavity when the pump was filled.
35. A disposable pump unit according to claim 34, wherein during
storage and transportation of the pump the preformed part of the
flexible membrane means is adapted to lie flush with the surface of
the pump cavity to reduce the susceptibility of the flexible
membrane means to damage during transit.
36. A disposable pump unit according to claim 31, wherein the
flexible membrane means comprise a laminate flexible film
comprising a layer of substantially non-stretchable polymer and a
layer of a heat-weldable polymer.
37. A disposable pump unit according to claim 31, wherein the
flexible membrane means comprises a layer of polyamide and a layer
of polyurethane.
38. A disposable pump unit according to claim 31, including a
variable fluid flow restrictor downstream from the cavity.
39. A disposable pump unit according to claim 31, wherein the body
includes a plurality of cavities and associated pluralities of
inlet ports, outlet ports, passageways and flexible membrane means,
the disposable pump unit being adapted to be coupled to a pump
actuator that operates the pump unit to fill at least one cavity
from the reservoir while simultaneously pumping fluid out of at
least one other cavity.
40. A disposable pump unit according to claim 39, including a fluid
flow channel interconnecting the outlet ports.
41. A disposable pump unit according to claim 31, wherein the body
includes a pair of cavities and associated pairs of inlet ports,
outlet ports, passageways and flexible membrane means, the
disposable pump unit being adapted to be coupled to a pump actuator
that operates the pump unit to fill one cavity from the reservoir
while simultaneously pumping fluid out of the other cavity.
42. A disposable pump unit according to claim 34, including a
plurality of passageways in the surface of the cavity that
communicate with the fluid flow passageway to inhibit, when the
pre-formed part of the flexible membrane means is urged by an
actuating fluid into the pump cavity, the formation of occluded
regions of fluid between the cavity wall and the flexible membrane
means, so that the flexible membrane means comes into contact with
substantially the whole surface of the cavity to ensure that
substantially all of the fluid flowed into the cavity from the
reservoir during filling of the pump is forced out of the cavity,
thereby to ensure that a substantially repeatable volume of fluid
is dispensed or metered from the pump.
43. A disposable pump unit according to claim 42, wherein the
plurality of passageways comprise a plurality of grooves.
44. A disposable pump unit according to claim 31, wherein the body
further has a chamber, downstream from the outlet port, for being
fluid coupled to a source of diluent and having a diluent inlet
whereby pumped fluid exiting the outlet port mixes with diluent in
the chamber.
45. A disposable pump unit according to claim 44, wherein the body
further has a plurality of obstructions in the chamber between the
outlet port and the diluent inlet for breaking up of the pumped
fluid to aid admixture of the pumped fluid and diluent.
46. A disposable pump unit according to claims 44, wherein the body
includes an outlet passageway downstream from the chamber, the
outlet passageway including mixing means.
47. A disposable pump unit according to claim 45, wherein the
mixing means is a static mixer through which an admixture of pumped
fluid and diluent flows.
48. A disposable pump unit according to claim 31, wherein the body
inlet port is fluid connected to a disposable reservoir containing
fluid to be supplied to the inlet port, so that when the reservoir
is empty the combined reservoir and pump unit may be disposed
of.
49. A disposable pump according to claim 48, including openable
closure means between the disposable pump unit and the reservoir,
so that the reservoir and disposable pump unit may be shipped
together while preventing flow of fluid from the reservoir into the
disposable pump unit.
50. A disposable pump unit according to claim 34, including a
reusable pump actuator for being coupled to the disposable pump
unit to provide actuating fluid to operate the disposable pump
unit, identification means for providing information about the
fluid to be pumped, and reader means for reading information
provided by the identification means, so that the operation of the
disposable pump unit and pump actuator may be adapted to the
information provided by the identification means.
51. A disposable pump unit according to claim 50, wherein the
identification means is a radio frequency identification (RDIF)
tag.
52. A disposable pump unit according to claim 50, wherein the
identification means is an Electro-Erasable-Programmable-Read Only
Memory (EEPROM) chip.
53. A disposable pump unit according to claim 39, wherein each
inlet port of the plurality of inlet ports is for being fluid
coupled to an associated one of a plurality of sources of fluid to
be pumped, the body including passage means for fluid coupling
together the plurality of outlet ports to provide a common outlet
for fluid pumped from the plurality of cavities, so that the
disposable pump unit may be operated by the pump actuator to
selectively dispense the respective fluids individually or in
combination.
54. A disposable pump unit according to claim 34, including a
reusable pump actuator releasably coupled to the disposable pump
unit body with the first and second portions of the flexible
membrane means interposed therebetween, the pump actuator including
means for providing positive and negative actuating fluid pressures
on the pre-formed part of the flexible membrane means opposite from
the cavity to move the pre-formed part into and out of the body
cavity to respectively pump fluid from the cavity and draw fluid
into the cavity, and first and second valve means respectively
associated with the inlet and outlet ports, each valve means
including a valve actuator means for operating the valve means to
move adjacent portions of the flexible membrane means against and
to allow adjacent portions of the flexible membrane means to move
away from the associated inlet and outlet ports to respectively
close and open the ports, such that when a negative actuating fluid
pressure is provided to the flexible membrane means to move the
pre-formed flexible means part out of the cavity the first valve
means allows the adjacent portion of the flexible membrane means to
move away from and open the inlet port and the second valve means
moves the adjacent portion of the flexible membrane means against
and closes the outlet port so that fluid may be drawn from a
reservoir through the inlet port and into the cavity, and such that
when a positive actuating fluid pressure is provided to the
flexible membrane means to move the pre-formed part of the flexible
membrane means into the cavity the first valve means moves the
adjacent portion of the flexible membrane means against and closes
the inlet port and the second valve means allows the adjacent
portion of the flexible membrane means to move away from and open
the outlet port so that fluid is pumped from the cavity and through
the outlet port.
55. A disposable pump unit according to claim 54 wherein each valve
actuator means includes an axially movable armature.
56. A disposable pump unit according to claim 54, wherein the valve
actuator means for the second valve means that is associated with
the outlet port includes a stepper motor operable to variably
control the size of the opening through the outlet port to provide
a variable flow restriction.
57. A disposable pump unit according to claim 55, including seals
around the armatures of the valve actuator means.
58. A disposable pump unit according to claim 54, wherein the
reusable pump actuator has a body including a surface with a cavity
therein, such that when the reusable pump actuator is coupled to
the disposable pump unit and negative and positive actuating fluid
pressures are provided the pre-formed part of the flexible membrane
means moves into and out of the pump actuator cavity such that the
pumped volume of fluid is defined on one side by the surface of the
pump cavity and on the other side by a surface of the pump actuator
cavity.
59. A disposable pump unit according to claim 58, wherein the
armature associated with the inlet port extends into a volume
defined between the pump actuator cavity and the flexible membrane
means of the disposable pump unit.
60. A disposable pump unit according to claim 54, wherein the pump
actuator includes means for detecting the presence or absence of
fluid in the disposable pump unit body cavity.
61. A disposable pump unit according to claim 60, wherein the
detecting means comprises ultrasonic detection means.
Description
[0001] This invention relates to improvements in fluid metering and
especially, but not exclusively, to the sanitary metering of very
viscous fluids, for example beverage concentrates.
[0002] In the food sector, for example, there is often a
requirement to dispense a metered amount of fluid foodstuff for use
as such or in admixture with a diluent such as water. It is
becoming increasingly important to be able to dispense fluids in a
sanitary manner where there is no possibility of outside
contamination of the fluid foodstuff or where companies want to be
able to assure the integrity of the fluid being dispensed.
Commonly, the fluid foodstuff is supplied in a disposable
container. For sanitary requirements to be met, it is desirable
that the fluid contacts only disposable parts of the system,
including the pump used to dispense the fluid. For this to be
economically viable, the pumping method should be simple and so
relatively inexpensive to produce.
[0003] In food dispense, and particularly in the beverage industry,
there is a common requirement to dispense an accurate ratiometric
mixture of a concentrate and a diluent. Common technologies involve
measuring the flow of the concentrate and then varying the diluent
flow to achieve the correct mixture. This has the disadvantage that
it involves measuring the fluid flow of, in particular, the
concentrate. Common methods include the use of turbine flow meters
and differential pressure flow meters. These techniques are however
not effective for measuring the flow of a highly viscous
concentrate such as an orange juice concentrate. Current methods of
dealing with these viscous fluids are to meter them using
peristaltic pumps or diaphragm type pumps integrated into
manifolds. While these methods work well for many relatively
viscous fluids, they do not work well for very highly viscous
fluids. For example, peristaltic type pumps typically become less
effective for fluids having a viscosity in excess of about 5000
centipoises. Non-disposable diaphragm pumps can be effective for
dispensing very viscous fluids but the manifold valving
arrangements for disposable sanitary diaphragm pumps are commonly
such that the fluid drag renders them unsuitable for use with very
viscous fluids.
[0004] Examples of disposable sanitary diaphragm pump designs are
proposed in U.S. Pat. No. 6,485,263. However, these designs either
utilise somewhat tortuous fluid inlet paths and additionally
require simultaneous control of different pressures to the three
parts of the pump--inlet valve, pump chamber and outlet valve (eg
as shown in FIG. 10) or, alternatively, they utilise solenoid
valves (e.g. as shown in FIG. 1) that are intended to be disposed
of with the other disposable pump components. The tortuous inlet
path shown in the FIG. 10 proposal would create considerable drag
on a highly viscous fluid and hinder the performance of the pump
resulting in a pump which is very limited in operating speed. This
problem could be overcome by pressurising the source of fluid that
is being dispensed by applying pressure internally to the fluid
reservoir or by having a flexible reservoir and applying pressure
externally. However, in sanitary systems, it is not acceptable to
apply internal pressure and to apply pressure externally involves a
much more complex and expensive system. The use of solenoid valves
in the pump unit intended to be disposed of, as shown in FIG. 1,
has the disadvantage that they are expensive.
[0005] It is the purpose of the present invention to provide an
improved sanitary fluid metering device which incorporates a
relatively cost-effective disposable pump arrangement and which is
capable of metering a highly viscous fluid.
[0006] According to a first aspect of the present invention, there
is provided a disposable pump unit for receiving and metering a
predetermined volume of fluid, the pump comprising a body having a
surface at which opens the mouth of a cavity formed in the body, an
inlet port for the fluid opening at the surface adjacent to the
mouth of the cavity whereby, when the inlet port is open, fluid can
flow from the inlet port into the cavity via the mouth thereof, a
first flexible membrane sealingly secured at its periphery to the
surface and overlying the cavity and the inlet port, an outlet port
for the fluid, there being a fluid flow passageway extending
through the body connecting the cavity to the outlet port, and a
second flexible membrane sealingly secured at its periphery and
overlying the outlet port, those portions of the first and second
flexible membranes, where they overlie the inlet and outlet ports
respectively, serving as closures for the ports.
[0007] The outlet port preferably also opens at the aforesaid
surface, in which case the first and second flexible membranes may
be integral with one another. Preferably, at least the first
flexible membrane, i.e. the membrane that overlies the cavity and
the inlet port formed in the body, is substantially non-stretchable
and is dimensioned such that, during the fluid metering step, it
can be urged by the actuating fluid into contact with substantially
the whole surface of the cavity wall whereby substantially all of
the fluid drawn from the reservoir during the fluid filling step is
pumped out during the fluid metering step. To that end, the first
flexible membrane (and the second flexible membrane where the two
are integral with one another) may, for example, comprise polyamide
film material. In a preferred embodiment, at least the first
flexible membrane comprises a flexible film or sheet of an
integrated laminate comprising a non-stretchable polymer, for
example a polyamide, and an underlying heat-weldable polymer, for
example a food-grade polyethylene, the latter having been
heat-welded to the body so as to be sealingly secured thereto as
aforesaid with the body comprising a moulding in a compatible
food-grade polymer, for example a polyethylene. An example of a
suitable laminate is S77 available from Amcor Flexibles Baricol.
Preferably the laminate is preformed to a shape substantially
similar to the shape of the surface of the pump cavity, such that
it substantially fully evacuates the cavity without the need for
the membrane material to stretch. Preferably during storage and
transportation the preformed shape of the laminate film lies flush
with the concavely curved surface of the pump cavity thereby
reducing the susceptibility of the membrane to damage during
transit.
[0008] In use, and in accordance with a second aspect of the
invention, a disposable pump unit of the invention is detachably
coupled to a re-usable pump actuator, with the said surface
sealingly abutting the pump actuator, comprising a source of
positive and negative pressure actuating fluid, preferably air, and
first and second valve actuating means associated respectively with
the inlet port closure and the outlet port closure, the arrangement
being such that, when the external surface of the first flexible
membrane (which acts as a pumping membrane) is exposed to the
source of negative pressure fluid, with the inlet port open and the
outlet port closed, it is drawn away from the disposable pump body
whereby fluid, such as a beverage concentrate, is drawn, from a
reservoir thereof via the inlet port, into substantially all of the
space defined by the cavity and the first flexible membrane ("the
fluid filling step"). Then, with the inlet port closed and the
outlet port open, when positive pressure fluid is applied to the
external surface of the first flexible membrane, the membrane is
urged back towards and into the cavity and pumps the fluid from the
cavity through the said passageway to the outlet port ("the fluid
metering step"). There may be a variable downstream flow restrictor
to enable the same fluid metering rate to be achieved for different
viscosity fluids with the application of the same positive
actuating fluid pressure. Alternatively, the fluid pressure could
simply be varied or a combination of variable downstream flow
restrictor and variable fluid pressure could be used. The
aforementioned variable restrictors and or pressure allow the
outlet flow of the pumped fluid to be varied, or alternatively
allow the output flow to be maintained substantially constant while
fluid properties, for example temperature, change.
[0009] The first valve actuating means associated with the inlet
port closure is preferably an axially movable armature that extends
into the volume subject to positive and negative pressure and seal
is provided where the armature protrudes into that volume;
preferably the seal is a rolling diaphragm type seal. The second
valve actuating means is likewise preferably an axially movable
armature and a like seal may also be provided. Provision of these
seals additionally prevents dirt ingress into the valve actuators
and enables use of cleaning fluids without the danger of the fluids
affecting the valve actuators, which may be electrically
driven.
[0010] Preferably, a disposable pump unit of the invention
comprises a body having a plurality of cavities each having
respective inlet ports, outlet ports and flexible membranes
whereby, when coupled to a pump actuator, fluid may be drawn into
at least one of the cavities whilst simultaneously being pumped out
of another. In this way, the unit may, where required, be used to
meter varying predetermined volumes of fluid in a substantially
continuous and efficient way. Preferably, the body has a pair of
cavities. Where there is a plurality of cavities, the simultaneous
fluid filling and fluid metering steps may be of different duration
such that when one dispensing step from one of the cavities is
complete the other is ready to commence, or has already commenced,
its dispensing step; this may be achieved by, for example, suitably
adjusting the negative and positive actuating fluid pressures by
means of adjustable pressure regulators.
[0011] Preferably, in a disposable pump unit of the invention, the
fluid flow passageway extending through the body and connecting the
cavity to the outlet port terminates at one end at a generally
concave wall defining the cavity, the wall having formed therein a
plurality of passageways that communicate with the fluid flow
passageway thereby to inhibit, during the fluid metering step, the
formation of occluded regions of fluid between the cavity wall and
the first flexible membrane and thus ensure that substantially all
of the fluid drawn from the reservoir thereof during the fluid
filling step is pumped out during the fluid metering step. Each of
the plurality of passageways is preferably a groove.
[0012] The combination of a disposable pump unit of the invention
and a re-usable pump actuator may constitute a beverage dispenser
as is more particularly described in our co-pending PCT application
of even date, the pump unit serving to meter a predetermined amount
of a beverage concentrate, for example orange concentrate, which is
then mixed with water, preferably in a predetermined ratio,
delivered by the dispenser. For that purpose in particular, the
body of the disposable pump unit preferably incorporates a diluent,
e.g. water, inlet communicating with an outlet passageway formed in
the body connected to the outlet port whereby, as fluid flows from
the outlet port through the outlet passageway, it mixes with the
diluent and is then dispensed into a receptacle such as a cup or
glass. Preferably downstream of the outlet port of the pump cavity
and immediately upstream of the diluent inlet are a number of
obstructions in the flow path adapted to break up of the pumped
viscous fluid to aid mixing with the diluent. The outlet passageway
preferably includes means, for example a static turbulator, to
assist the admixture of the fluid and diluent.
[0013] Further, there may be provided means to adjust the diluent
flow rate and feedback means so as to ensure substantially constant
ratiometric mixing at a target dispense rate.
[0014] The pump actuator includes a complementary surface that
abuts the aforesaid surface of the disposable pump unit. Both
surfaces are preferably substantially planar. An essential function
of the pump actuator surface is to control the degree to which the
first flexible membrane can be drawn away from the disposable pump
body and therefore in part to define the predetermined metered
volume of fluid. Preferably, the surface of the pump actuator also
has at least one recess (the number corresponding to the number of
cavities in the disposable pump body) defined in it for receiving
the first flexible membrane during the fluid filling step, the
recess wall serving to limit movement of the membrane. The
cavity(ies) of the disposable pump unit and recess(es) (if any) of
the pump actuator are preferably concave in form.
[0015] Preferably, each pump actuator has associated with each
recess a means of detecting whether the or each recess is full of
fluid or is empty. Preferably the detecting means comprises
ultrasonic transducers, the variance in signals from which indicate
the volume of fluid within each recess.
[0016] Another function of the pump actuator is to provide
actuating means for the closures of the inlet and outlet ports. The
actuating means for the inlet preferably comprises a
solenoid-operated armature which, by means of a compression spring,
urge part of the respective flexible membrane into sealing contact
with the inlet port in order to close it, but which assume, when
the solenoid is energised, a spaced position from the membrane when
the port is required to be open. It will be recognised to those
skilled in the art that other conventional actuation means, for
example pneumatic, could be used to drive the armature in place of
the solenoid described above. In a preferred arrangement the valve
actuating means associated with the outlet port closure is capable
of affecting a variable, pre-selected, degree of opening of the
outlet port. This may be achieved by using, for example, a stepper
motor or a variable end stop solenoid associated with an armature
or other actuator that acts upon the second flexible membrane where
it overlies the outlet port. This feature enables the disposable
pump unit to control the outlet flow rate as desired depending upon
the viscosity of the fluid being metered. For example, with a
relatively higher viscosity fluid, it may be desirable to have the
outlet fully open in order to achieve the desired outlet flow rate
and hence the required ratiometric mixing control with a diluent
such as water, whereas with a relatively lower viscosity fluid it
may be desirable to have the outlet only partially open for that
purpose.
[0017] Alternatively, for example, the armatures may be
pneumatically operated. In order to improve the fluid seal between
the ports and the flexible membranes in the port-closed position,
each port is preferably surrounded by a raised lip. Preferably the
actuating means are provided with soft tips, for example of a
silicone rubber, which do not damage the membrane and provide an
even pressure on the raised lip.
[0018] The disposable pump unit is preferably permanently connected
to, or integral with, a reservoir containing the fluid so that,
once the reservoir is empty or otherwise needs to be changed, the
combined reservoir and pump unit are disconnected from the pump
actuator and may be disposed of. A replacement reservoir/pump unit
may then be connected to the pump actuator. Preferably a closure is
provided between the pump unit and the reservoir such that the
reservoir and disposable pump unit may be shipped together whilst
preventing the migration of fluid into the disposable pump unit.
Once in situ and connected to the pump actuator the closure is
moved from a closed position in which flow between reservoir and
disposable pump unit is blocked to an open position in which fluid
may flow from the reservoir to the disposable pump unit. Especially
in the drinks dispense context, the reservoir and disposable pump
unit is preferably refrigerated by a refrigeration system comprised
in the re-usable part of a drinks dispense machine and which may
also serves to cool said diluent. In a preferred arrangement, the
action of loading and unloading the disposable pump unit from the
pump actuator automatically opens and closes the closure
respectively.
[0019] It will be appreciated that the metered fluid comes into
contact with only components of the disposable pump unit and,
therefore, that the pump actuator may be continually re-used
without the need to clean it regularly. Thus, the pump actuator
will be part of, for example, a fixed drinks dispense machine
installed in a bar, restaurant or the like, it being possible for a
given machine to dispense different beverages depending on the
nature of the fluid concentrate contained in a selected
reservoir/disposable pump unit. Because different concentrates will
usually require different degrees of dilution, the disposable pump
unit preferably includes an identification means and the re-usable
pump actuator includes reading means for automatically reading the
identification means whereby the combined pump/pump actuator, for
example a drinks dispense machine, may adapt its dispense mode,
e.g. diluent flow rate, and/or provide audio and/or visual
information to the user in dependence upon the characteristics
identified. Such characteristics may include, for example, one or
more of the viscosity of the fluid to be metered in a particular
case, its type (e.g. orange juice or otherwise), its
shelf-life/expiry date and the desired dilution ratio. The
identification means and the reading means may be based on, for
example, radio frequency identification (RDIF) technology,
Electro-Erasable-Programmable-Read Only Memory (EEPROM) chips, bar
code technology or colour-sensing technology, the general nature of
all of which are known. Preferably the reusable pump actuator has
associated therewith a read/write device that is capable of both
reading information from an identification means associated with
the disposable pump unit and writing information to said
identification means.
[0020] According to a third aspect of the present invention, there
is provided a disposable pump unit as defined above adapted for
mixing two or more fluids, especially viscous fluids, the body
defining two or more said cavities and an inlet port associated
with each cavity and with reservoirs for the respective fluids, and
a common outlet associated with the cavities, whereby the fluids
may, in association with a re-usable pump actuator, be dispensed
simultaneously and mixed. Such a unit has a number of diverse
applications, and we mention by way of example the mixing of the
two precursor materials of epoxy resins (e.g.
"Araldite"--Registered Trade Mark).
[0021] Embodiments of the invention will now be described by way of
example only, with reference to the accompanying drawings in
which;
[0022] FIG. 1 is a perspective view of a disposable pump unit of
the invention;
[0023] FIG. 2 is a longitudinal cross-section of the disposable
pump unit of FIG. 1;
[0024] FIG. 3 is a perspective view of a pump actuator for assembly
with the pump unit shown in FIGS. 1 and 2;
[0025] FIG. 4 is a cross-section of the assembled pump unit and
pump actuator;
[0026] FIG. 5 is a perspective view of the pump unit shown in FIG.
1 additionally having a diluent inlet;
[0027] FIG. 6 is a similar view to FIG. 5, but in which the pump
outlet has an integral convoluted path mixing section;
[0028] FIG. 7 is a perspective view of a disposable pump unit of
the invention showing the channels provided for prevention of
occluded volumes of fluid in the pump;
[0029] FIG. 8 is a perspective view of a disposable pump unit of
the invention showing the closure between the pump unit and the
reservoir; and
[0030] FIG. 9 is a perspective view of a pre-formed membrane for
use with the the disposable pump unit.
[0031] Referring to FIGS. 1 and 2, a dual-chamber disposable pump
unit 100 is shown. A fluid inlet 14 splits to feed each of the two
pump cells 1a, 1b comprised in a rigid body 2 having on a
substantially flat surface thereof an area 3 containing a chamber
inlet port 4, the inlet port 4 being surrounded by a raised lip 5,
and a concave cavity 6 defining one side of a pump chamber 7. The
second side of the chamber 7 comprises a membrane 8 made of a
flexible sheet material, e.g. low density polyethylene (LDPE),
sealingly secured about its periphery to the aforesaid surface of
the body 2 so as to enclose each fluid inlet area 3 and their
respective concave cavities 6 such that fluid can pass from the
inlet port 4, when open, to the respective concave cavities 6.
Located in each concave cavity 6 of each pump chamber 1a, 1b is an
array of chamber outlets 9. Each chamber outlet 9 is in fluid
communication with a closable outlet port 10 surrounded by a raised
lip 11. The flow paths from the two closable outlet ports 10
converge together into a single outlet 12. The two closable outlet
ports 10 and the outlet 12 are together sealingly enclosed by a
membrane 13 comprising flexible sheet material, shown to be
integral with the membrane 8, secured about its periphery to the
aforesaid surface of the body 2.
[0032] Referring to FIG. 3, a non-disposable pump-actuating unit
200 for the dual chamber pump unit 100 is shown. The actuating unit
200 comprises a rigid body 15 containing two concave cavities 16,
each surrounded by a gasket seal 17. The concave cavities 16 and
the gasket seal 17 are shaped such that they match the shape of the
pump cells 1a, 1b so that when placed in contact with them they
form a seal around the circumference of the pump cells 1a, 1b.
Located within each cavity 16 is a compressed air inlet/exhaust
port 18 defined in part by cross-shaped channels extending over a
substantial basal area of the cavity 16. Also located within each
cavity 16 is a solenoid-operated armature 19 which extends through
the body 15 and into the cavity 16. A pair of armatures 20 also
extends through the body 15 adjacent to the cavities 16.
[0033] Referring to FIGS. 1, 2 and 4, the pump-actuating unit 200
is shown in FIG. 4 to be releasably connected to the disposable
pump unit 100 to form a complete pump. The cavity 16 in the unit
200 together with the membrane 8 forms an actuating chamber 21
connectable alternately to supplies of negative and positive
pressure air via a passageway 22. Each cavity 16 in the
pump-actuating unit 200 and its opposed cavity 6 in the disposable
pump unit 100 together define a fixed volume of fluid that will be
displaced on each cycle of the pump. The sequence of operation of
the pump is that each armature 20 extends so as to urge the
membrane 13 locally onto the respective raised lips 11 of the
outlet ports 10 thus closing the pump chamber outlet, and the
armature 19 is spaced from the membrane 8 such that the flow path
between the inlet port 4 and the concave cavity 6 is open.
Armatures 19 and 20 have associated seals 19a, 20a, which prevent
ingress of any substances past the armatures.
[0034] A first source of pump actuating fluid at a negative
pressure, ie below ambient pressure, is connected to the actuating
fluid port 18 via the passageway 22, the application of the
negative pressure causing the flexible membrane 8 to be drawn
towards and into the cavity 16 thereby drawing fluid into the
latter from a reservoir (not shown) via the inlet 14 and the inlet
port 4, the inlet port 4 being held open by the negative pressure
tending to lift the membrane 8 locally away from the inlet port 4.
The cross-shaped channels of the port 18 ensure that the membrane 8
can be drawn fully into the cavity 16 and prevents the membrane 8
from blocking the port 18 before the membrane 8 is substantially
fully withdrawn into the cavity 16. When the membrane 8 is fully
drawn into the cavity 16 and the volume defined by the cavity 16
and the cavity 6 is filled or substantially filled with the fluid
to be dispensed, the armatures 19 and 20 are actuated such that
armature 19 is moved towards the pump cell, locally pressing the
membrane 8 against the raised lip 5 of the inlet port 4 to close
the flow path between the inlet 14 and the pump chamber 7, and
armature 20 moves away from the outlet port 10 allowing the
membrane 13 to move away from the outlet port 10 of the pump cell
outlet (12, FIG. 1). Substantially at the same time, positive air
pressure is applied to the membrane 8 via the port 18 which urges
the membrane 8 towards and substantially fully into the cavity 6
whereby the fluid is pumped out through the outlet 12 via the
outlet port 10. The pump filling/dispense cycle may then be
repeated. The outlet armatures 20 are attached to stepper motors
20b which can vary the position of the each 20 in relation to the
raised lip 11 of its respective outlet port 10 thereby allowing the
opening of the outlet valve to be controlled to vary the outlet
flow of the pump.
[0035] In operation, the two pump cells may be operated in opposite
phase such that when one is dispensing the other is filling, the
filling cycle preferably being faster than the dispense cycle such
that there can be a slight overlap of the dispensing cycles to
ensure constant output. If there are more than two pump cells then
it is not necessary for the filling cycle to be faster than the
dispense cycle.
[0036] Referring to FIG. 5, a pump unit is shown which is similar
to that shown in FIG. 1 and operates in the same manner, but which
has the additional feature of a diluent inlet 23 through which a
diluent enters the pump cell and mixes with the pumped fluid to
pass with it through the pump cell outlet 12 whereby diluted fluid
is dispensed. The flow of the diluent is controlled by means of an
external control valve (not shown) which may be variable and
controlled to give a constant ratiometric mixture of pumped fluid
to diluent.
[0037] Referring to FIG. 6, a pump unit is shown which is similar
to that shown in FIG. 5 and operates in the same manner. However,
in addition, it comprises a mixing section 24 downstream of the
point at which the diluent is added. Where the pumped fluid is of a
high viscosity (e.g. above 10,000 centipoises) it becomes
increasingly difficult to obtain a homogeneous diluted fluid; the
convoluted path 25 of the mixing section 24 is designed to shear
the viscous fluid and create turbulence to ensure that the two
components mix fully.
[0038] Referring to FIG. 7 a rigid plastic pump unit is shown
comprising of a fluid inlet 14 leading to two chamber inlet ports 4
from which there is a flowpath to the concave cavity 6 and its
associated chamber outlet 9. Provided in surface of the concave
cavity 6 and the flat area 3 are recessed grooves 26 which, should
the flexible film (not shown) trap an occluded area of the pumped
fluid remote from the chamber outlet 9, there will always be a
channel for the fluid to be forced out of ensuring that the chamber
is fully emptied every, thus giving a repeatable volumetric output.
The pump unit shown in this figure has had all excessive plastic
removed and designed for production by injection moulding
techniques.
[0039] Referring to FIG. 8 the rigid plastic pump unit of FIG. 7 is
shown further comprising an integrated static mixer 27 which is
formed as a feature of the plastic moulding enclosed by the
flexible film which is heat welded thereover. Additionally an array
of obstructions 28 are provided between the outlet ports 10 and the
static mixer 27 such that the fluid is sheared immediately prior to
it admixing with the diluent entering via diluent inlet 23. Once
admixed with the diluent the fluid passes through the static mixer
27 and is dispensed therefrom as a homogeneous fluid. In the fluid
inlet (14, FIG. 7) is a closure 29 which is rotatable by means of
lever 30 to open or close the flow from the reservoir (not shown)
to the inlet ports 4.
[0040] Referring to FIG. 9 a pre-formed flexible membrane suitable
to be heat welded to a pump zone of the invention is shown.
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