U.S. patent application number 14/489708 was filed with the patent office on 2015-03-19 for pressure differential pumps.
The applicant listed for this patent is MAG AEROSPACE INDUSTRIES, LLC. Invention is credited to Razmik Boodaghians, Sung Hong, Kevin Huang, Shane Nazari, Christina Ortolan, Nguyen Tram.
Application Number | 20150078919 14/489708 |
Document ID | / |
Family ID | 51656110 |
Filed Date | 2015-03-19 |
United States Patent
Application |
20150078919 |
Kind Code |
A1 |
Hong; Sung ; et al. |
March 19, 2015 |
PRESSURE DIFFERENTIAL PUMPS
Abstract
Embodiments of the present disclosure relate generally to pumps
and systems that use a differential pressure gradient to transfer
fluids. In one example, the pumps may use available differential
pressure that exists due to outside pressure and cabin pressure due
to altitude on-board a vehicle such as an aircraft.
Inventors: |
Hong; Sung; (Los Angeles,
CA) ; Boodaghians; Razmik; (Glendale, CA) ;
Tram; Nguyen; (Chino Hills, CA) ; Huang; Kevin;
(Los Angeles, CA) ; Nazari; Shane; (Glendale,
CA) ; Ortolan; Christina; (Long Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAG AEROSPACE INDUSTRIES, LLC |
Carson |
CA |
US |
|
|
Family ID: |
51656110 |
Appl. No.: |
14/489708 |
Filed: |
September 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61879872 |
Sep 19, 2013 |
|
|
|
Current U.S.
Class: |
417/54 ;
417/148 |
Current CPC
Class: |
F05C 2251/08 20130101;
F04B 9/1207 20130101; F04B 7/0266 20130101; F04B 9/1256
20130101 |
Class at
Publication: |
417/54 ;
417/148 |
International
Class: |
F04B 9/12 20060101
F04B009/12; F04B 9/125 20060101 F04B009/125; F04B 7/02 20060101
F04B007/02 |
Claims
1. A pump system configured to use differential pressure,
comprising: a pump body comprising at least one vacuum/air inlet,
at least one fluid inlet, at least one fluid outlet, a reservoir
configured for containing a fluid, and a vacuum control member for
controlling application of vacuum to the reservoir; at least one
piston element housed within the pump body, the at least one piston
element configured to move in response to a pressure differential
created by application or removal of vacuum to the reservoir
through the at least one vacuum/air inlet.
2. The system of claim 1, wherein the at least one piston is moved
via a vacuum created, via a spring, via magnetic force, or any
combination thereof.
3. The system of claim 1, wherein the at least one piston is
comprised of one or more shape memory alloys.
4. The system of claim 1, wherein the at least one piston comprises
a hydraulic cylinder.
5. The system of claim 1, wherein the at least one piston comprises
a spring piston under compression when vacuum is applied.
6. The system of claim 1, wherein the at least one piston is
configured to contract upon application of vacuum to the at least
one vacuum inlet as fluid is pulled into the reservoir via the at
least one fluid inlet.
7. The system of claim 6, wherein the at least one piston is
configured to extend upon removal of vacuum to push the fluid out
of the reservoir, through the at least one fluid outlet.
8. The system of claim 1, wherein the at least one piston comprises
a piston head and a piston yoke, and further comprising a sleeve
around the piston yoke.
9. The system of claim 1, further comprising one or more piston
seals maintained via a low-friction sleeve.
10. The system of claim 1, wherein the at least one piston is
guided via internal rails.
11. The system of claim 1, further comprising a first valve at the
at least one inlet, a second valve at the at least one outlet, and
a third valve at the vacuum control member.
12. The system of claim 1, wherein the at least one piston
comprises two pistons that extend into the reservoir to force fluid
out through the outlet.
13. The system of claim 12, wherein the two pistons are timed for
multi-stroke action.
14. The system of claim 1, wherein the at least one piston is
physically isolated from pumped fluids.
15. The system of claim 1, wherein the pump body is comprised of a
high-density plastic polymer.
16. The system of claim 1, wherein the at least one vacuum/air
inlet comprises a first vacuum inlet and a second vent air
inlet.
17. A method of using differential pressure to move fluid through a
pump system, comprising: providing a pump body comprising a vacuum
inlet, a fluid inlet, an outlet, a vacuum control member, and a
reservoir configured for containing a fluid; at least one piston
housed within the pump body, the at least one piston configured to
move in response to a pressure differential; applying a first
pressure to the vacuum inlet to create a first movement of the
piston and to cause fluid to enter the reservoir through the at
least one fluid inlet; venting the first pressure through the
vacuum control member to create a second movement of the at least
one piston, forcing fluid out the outlet.
18. The method of claim 17, wherein the at least one piston
comprises a spring, and wherein the first movement comprises
compression of the spring, and wherein the second movement
comprises expansion of the spring.
19. The method of claim 17, further comprising a first valve at the
inlet, a second valve at the outlet, and a third valve at the
vacuum control member, and further comprising causing fluid to
enter the reservoir by opening the first valve when the second
valve is closed; and opening the third valve to vacuum.
20. The method of claim 17, further comprising a first valve at the
inlet, a second valve at the outlet, and a third valve at the
vacuum control member, and further comprising causing fluid to exit
the reservoir by closing the first valve when the second valve is
opened; and opening the third valve to vent.
21. The method of claim 17, wherein the at least one
tension-compression element comprises two pistons that extend into
the reservoir to force fluid out through the outlet.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/879,872, filed Sep. 19, 2013, titled
"Pressure Differential Pump," the entire contents of which are
hereby incorporated by reference.
FIELD OF THE DISCLOSURE
[0002] Embodiments of the present disclosure relate generally to
pumps and systems that use a differential pressure gradient to
transfer fluids. In one example, the pumps may use available
differential pressure that exists due to outside pressure and cabin
pressure due to altitude on-board a vehicle such as an aircraft. In
other examples, the pumps may use a created differential pressure,
such as that created by a vacuum generator pump on any vehicle. The
pumps and systems may be designed to transport any type of fluids,
non-limiting examples including fluids that may contain suspended
solids, such as black or grey water, anti-freeze, or any other
fluids.
BACKGROUND
[0003] Often aboard passenger transportation vehicles, there exist
high or low pressure systems as a consequence of propulsion or
environmental conditions. For example, an aircraft in flight may
experience a pressure differential that is created between the
atmosphere outside the aircraft at an altitude and the internal
pressurized cabin atmosphere. These high or low pressure systems
represent useful differential pressure gradients that can be used
to drive certain mechanical processes.
BRIEF SUMMARY
[0004] Embodiments described herein provide a pump system
configured to use differential pressure. The pump system may
generally include a pump body comprising at least one vacuum inlet,
at least one fluid inlet, an outlet, a vacuum control member, and a
reservoir configured for containing a fluid. There may be at least
one piston housed within the pump body, the piston configured to
move in response to pressure differential. The piston may include a
spring body or any other tension-compression storing system that
can be compressed when subjected to vacuum and that expands when
the pump body is vented to ambient pressure. It is also possible
for the pump to work such that a difference in pressure forces a
hydraulic cylinder to move across the pump body, forcing movement
of fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 shows a side view of one embodiment of a pump system
that uses differential pressure to move fluids.
[0006] FIG. 2 shows a side exploded view of a piston that may be
contained within a pump body.
[0007] FIG. 3 shows a perspective view of the piston components of
FIG. 2.
[0008] FIG. 4 shows a side cut-away view of a pump body with a
vacuum applied to compress piston components or to otherwise force
the pistons open to create a reservoir space in the pump body.
[0009] FIG. 5 shows a side cut-away view of FIG. 4 with the pistons
expanded to force fluid out of the reservoir.
[0010] FIG. 6 shows a schematic of a pump using a hydraulic
cylinder to force fluid out of the reservoir.
[0011] FIG. 7 shows a cross-sectional view of a pump body having
internal rails for guiding a piston.
DETAILED DESCRIPTION
[0012] Embodiments of the present disclosure provide pumps designed
to work based on differential pressure. The potential energy
represented by differential pressure is particularly attractive in
passenger transport vehicles, due to limitations on size, weight,
and electrical energy inputs for various components. The present
inventors thus determined that it would be beneficial to design
pump devices that can use this energy source. Due to the inherent
movement of passenger transportation vehicles as well as necessary
size and weight restrictions for components to be used on such
vehicles, on-board mechanisms are desirably small, lightweight,
reliable, and able to function in a range of temperatures and
environments. The pressure-differential pumps (PDP) described
herein are devices that use the various pressure regimes available
on-board a passenger transportation vehicle to drive fluids from
one location to another.
[0013] FIG. 1 shows one example of a pressure differential pump
(PDP) system 10. This system includes a pump body 12. The pump body
12 may be made up of two body components 14, 16. However, although
two body components 14, 16 are shown in FIG. 1, it should be
understood that the body components 14, 16 may be integrally
molded. It should also be understood that the pump body may be
formed as a single integral body. Alternatively, there may be more
than two body components provided to form the pump body 12. In the
specific embodiment shown in FIG. 1, the body components 14, 16 may
be formed as pinch valves. The general concept is that the pump
body 12 has a reservoir 18 that can contain a fluid, and the pump
body can move the contained fluid. The pump body 12 may receive a
first applied pressure, and may use that pressure to move contained
fluid toward an area having a different pressure. By using
different pressure gradients, the system 10 can move fluids without
using a high amount of power.
[0014] In one example, the pump body 12 forms a reservoir 18. The
reservoir 18 may generally include one or more seals to prevent air
and liquid leakages. The reservoir may be in fluid communication
with an outlet 20. The outlet 20 is an exit point for the contained
fluid to leave the pump body 12. In a specific embodiment, there
may be more than one fluid outlet 20 provided. The pump body 12
also has at least one fluid inlet 22. The at least one fluid inlet
22 allows any type of fluid to be received into the reservoir 18 of
the pump body 12. In a specific embodiment, there may be more than
one fluid inlet 22 provided. In FIGS. 1 and 4, a pump inlet 22 is
positioned on an outer surface of the pump body (leading to the
reservoir 18). A pump outlet 20 is positioned generally opposite
the inlet 22 on outer surface of the pump body 12 (leading away
from the reservoir 18).
[0015] Fluid may be delivered into the pump body reservoir 18 using
any appropriate manner. In one example, the fluid may be forced
into the reservoir 18 from another system. The fluid may be grey
water from a sink basin that flows into the pump body 12. The fluid
may be potable water delivered from an on-board water tank. The
fluid may be anti-freeze to be delivered to one or more aircraft
components. The fluid may be grey water that has been filtered,
collected, and reserved from a sink for delivery to a toilet for
flushing purposes. The type of fluid to be moved via a pump system
10 is not intended to be a limiting factor of the pump structures
described. In another example, the volume of the pump reservoir 18
may collect fluids (from any source) drawn in by the vacuum-driven
retreating action of one or more pistons 26, described further
below. An inlet check valve (A) may allow fluids to be pulled into
the pump through the fluid inlet 22, but prevent them from flowing
backwards through the system during compression. Similarly, an
outlet check valve (B) may allow fluids to pass through the outlet
20 (toward the pumping destination) during compression without
allowing high pressure, downstream fluids to flow backward.
[0016] For example, as shown in FIG. 2, a piston system may be used
to move water through the pump body 12. This example may include at
least one tension-compression element that may be housed within the
pump body 12. In one embodiment, the piston may include a
compressible feature, such as a tension-compression element spring
body 28, and a head 30. The piston head 30 may be attached to a
yoke 50, with the spring body 28 positioned within. The yoke 50 may
be a sliding yoke that helps create movement of the piston. The
yoke 50 may also feature a sleeve 32, such as an elastomeric sleeve
32, around its circumference. The sleeve 32 may slide with the yoke
50 and help reduce or alleviate friction between the yoke 50 and
the pump body 12 interior.
[0017] In an alternate embodiment, the piston may comprise a
compressible substance, such as gas, that can force movement of the
piston head 30. In any event, the piston is generally compressed
when the pump body is open to vacuum, but expanded when the pump
body is open to vent or ambient pressure. As shown in FIG. 3, the
spring body 28 can be received in the yoke 50, which is received in
the pump body 12 in use. In one example, the spring body 28 of the
piston may have a normally-extended resting state. This is
illustrated in FIGS. 2 and 3. As shown in FIG. 4, a second piston
34 (with related components) may be positioned in the pump body 12
as well. The pistons 26, 34 may be positioned on opposing sides of
the pump body 12, such that when retracted, they help define the
reservoir 18.
[0018] In one example, the piston(s) may be formed of yoke 50 that
is configured as a hollow cylinder suspended within an elastomeric
sleeve 32. Differential pressure may be applied to a sealed region
behind the yoke/cylinder barrel. One or more
tension/compression-storage components 28 may be located within
this sealed region. In one embodiment, the tension-storage
component may be a spring. The elastomeric sleeve 32 may act to
atmospherically isolate the interior of the region behind the
cylinder by bending or folding, while maintaining a seal, without
sliding past itself or other components. This design can allow for
reduced friction motion by eliminating a sealing component such as
an o-ring. (However, it should be understood that an o-ring may be
used instead or additionally.) This design can also allow the
compression of the piston 26 via pressure differential benefit,
while ensuring that remaining pump components remain isolated from
the pumped fluids. This contributes to the overall reliability of
the system over existing pump architectures. In one example, a
low-friction sleeve 32 may be attached to a piston head 30 and
piston yoke 50.
[0019] In another embodiment, piston guidance may be maintained via
one or more internal rails 48 instead of (or in addition to) an
o-ring-containing piston or a sleeve 32. The internal rails 48 may
assist with assembly of the pump body components. The internal
rails 48 may also help keep the piston from rotating in use. One
example of one or more internal rails 48 positioned on an internal
surface of the pump body is shown in FIG. 7. The piston 26 may be
provided with one or more protrusions that slide within the rails
48. Alternatively, the rails may be provided as an elongated
protrusion on the pump body, and the piston may have one or more
grooves that receive the elongated protrusion in use.
[0020] The movement of the piston(s) 26, 34 may be controlled by
differential pressure. For example, most passenger aircraft and
other passenger transport vehicles have a vacuum disposal system
that applies vacuum to transport waste water from toilets and/or
sinks into an on-board waste water storage tank. In aircraft, the
vacuum is generated either by the pressure differential between the
pressurized cabin and the reduced pressure outside of an aircraft
at high flight altitudes or by a vacuum generator at ground level
or at low flight altitudes. The pressure differential created by
either system can be used to force the piston 26 to contract and to
pull water into the space created by such movement.
[0021] In use, the interior of two normally-extended pistons 26, 34
may be exposed to vacuum. It is possible for each piston to be
exposed independently to the same vacuum source or for them to be
connected to separate vacuum sources. In any event, exposure to
vacuum allows atmospheric pressure to push the pistons 26, 23 back
into the yokes/cylinder barrels 50, into a contracted state. In
this position, the spring 28 on each piston 26, 34 may be
compressed and stores the potential energy provided by the
differential pressure gradient. It is with this potential energy
that fluids can be pumped. In other embodiments, the pistons may be
moved via vacuum alone, via hydraulic pressure, or via magnetic
force. In one example, the pressure differential/vacuum may be
applied to the pump body 12 via at least one vacuum inlet 36. The
at least one vacuum inlet 36 may deliver a vacuum created by an
on-board vacuum generator or vacuum created by the difference in
pressures between the aircraft cabin and the outside atmosphere.
FIG. 1 shows an embodiment that uses two vacuum inlets 36, 38
controlled by a vacuum control member 40. It should be understood,
however, that only one vacuum inlet need be provided (as shown in
FIGS. 4 and 5) or that more than two vacuum inlets may be provided.
As shown in FIG. 4, an application of differential pressure to the
pump body 12 can force the piston 26 to contract. This contraction
creates spaces and vacuum for the entry of fluid into the at least
one fluid inlet 22. The inlets described herein may be operated by
valves, such as pinch valves, solenoid valves, or any other
appropriate valve that can control the flow of fluids (either
liquid or gases).
[0022] A control member 40 may also be provided as a part of the
pump system 10. Control member 40 may be controlled by a vent valve
(C), which may toggle between venting the system via a vent channel
44 or allowing vacuum to be applied to the system via a vacuum
channel 46. Control member 40 can cause the removal of the vacuum
from the pump body, creating a pressure gradient, which can force
the piston(s) 26, 34 to expand, pushing the fluid contained in the
reservoir 18 out through the outlet 20. An example of vent being
applied to the pump body 12 to create a flush state is shown in
FIG. 5. In this Figure, the pistons have expanded into the
reservoir, which forces the fluid contained in the reservoir out as
a high force/pressure/velocity.
[0023] Referring now more specifically to FIG. 4, the function of
the various valves (a, b, and c) that coordinate flow of fluid is
described. The below description is for use of the pump to receive
grey water and to deliver the grey water to a toilet for a flush
sequence, but it should be understood that other uses are possible
and within the scope of this disclosure. When a vacuum is applied
to the pump body 12, the inlet valve (a) is open, allowing grey
water/fluid to enter the reservoir 18. (This entry may be via
gravity, via pull from pressure, or via external pump, or any other
appropriate method.) The outlet valve (b) is closed. The
vent/vacuum valve (c) is opened to vacuum and closed to vent. (This
valve (c) may be a 3-way valve or any other appropriate form of
valve.) The pistons 26, 34 are compressed.
[0024] Entry of grey water into the reservoir 18 allows the
downward passage of fluid, while preventing the upward backflow.
Once a flush request is sent from the toilet to the pump system 10,
the following actions may occur to initiate the "pump state" shown
in FIG. 5: the inlet valve (a) will close, the outlet valve (b)
will open, the vent/vacuum valve (c) will open the vent channel 44
and close the vacuum channel 46. These actions may cause the
pistons 26, 34 to expand, pumping the grey water/fluid out of the
reservoir 18 through valve (b) and out the outlet 20.
[0025] Once the pistons are fully expanded, the following actions
may occur to revert back to the "normal state" shown in FIG. 4: the
inlet valve (a) will open, the outlet valve (b) will close, the
vent/vacuum valve (c) will close the vent channel 44 and open the
vacuum channel 46. These actions will cause the pistons 26, 34 to
compress, preparing the reservoir 18 for another cycle of refill
with grey water. The valves used in this system may be any
appropriate form of valve. It has been found that solenoid valves
may be particularly useful.
[0026] When fully extended, the pistons 26, 34 may be designed to
occupy a significant majority of the available volume of the pump
reservoir 18. The reservoir 18 shape may be optimized, depending
upon the application of the pump system, such that the required
pressure and volume of fluid can be delivered via the pumping
action of the pistons. Further, piston action can operate in a
single-stroke or multi-stroke fashion, delivering a bolus of pumped
fluid or a pulsed stream.
[0027] In a single-stroke configuration, the full volume of the
pump reservoir may be expelled during extension of the piston(s).
The pressure of the pumped fluid may change in proportion to the
available tension in the spring. As the spring returns to its
uncompressed state (e.g., at the end of the stroke), the pressure
of the fluid may be found to diminish. In this manner, fluid would
generally be pumped as a discrete bolus, with a high initial
pressure that diminishes over the course of the stroke.
[0028] In a multi-stroke configuration, the reservoir volume may
only be reduced by a fraction during each piston stroke, allowing
the fluid to be pumped at a generally high pressure, due to
conservation of tension within the piston spring. Because each
stroke is physically shorter, the differential pressure can more
readily drive the piston recovery, allowing for rapid repetition of
strokes. If a two-piston pump configuration is used, as shown in
FIGS. 4 and 5, the piston actions may be timed to allow for a
fairly smooth, constant flow of fluid as each piston complements
the slack left by the decompression of the other piston's
spring.
[0029] In some embodiments, it is envisioned that the pressure
differential pump may use shape-memory alloys to achieve
non-diminishing pumping pressures throughout the linear stroke of
the piston. For example, the tension-compression element of the
piston may comprise a shape memory material. Shape-memory allows,
non-limiting examples of which include copper-aluminum-nickel or
nickel-titanium, can be utilized such that the energy released
during spring decompression can be supplanted by the reversible
changes in these shape-memory alloys.
[0030] The pump system 10 may feature one or more level sensors,
which may be comprised of non-intrusive capacitive sensors, to
detect when and whether the reservoir 18 is full. The pump system
10 may also feature one or more controllers that send signals to
the vacuum control member 40 to open and close the valves at the
inlet and outlet and in order to effect pump activation and
movement of the desired fluid.
[0031] In an alternate embodiment, rather than relying on spring
motion to cause movement of the pistons, the pistons may operate
based on vacuum alone. A vacuum may be applied to cause the piston
to expand, pushing the fluid out of the reservoir.
[0032] In a further embodiment, it is possible to provide a single
piston that is operated by pressure differentials across two ends
of the pump body. At one end, a first pressure differential causes
movement of a piston and pulls water into the reservoir 18. Once
the reservoir is full or when the pump is otherwise activated, a
second pressure differential that enters at the second end of the
pump body 12 can cause opposite movement of the piston and force
fluid out of an outlet.
[0033] In a further embodiment, the pump system 10 may be activated
by hydraulic pressure. For example, as shown in FIG. 6, one or more
hydraulic cylinders 42 may be used to move fluid through the pump.
The pump body 12 is generally provided with at least one fluid
inlet 22, at least one fluid outlet 20, a liquid chamber 52, and an
air chamber 54. The fluid inlet 22 and fluid outlet 20 are
generally governed by check valves or other features that prevent
flow of liquid until the valves are opened. A hydraulic cylinder 42
may be positioned within the liquid chamber 52 and used to force
movement of the water that enters the chamber 52 out through the
inlet 22. The hydraulic cylinder 42 may be operated by a pressure
created by fluid built up in the chamber 52 when the inlet and
outlets are closed via valves. The hydraulic cylinder 42 may be
operated by compressed gas or any other appropriate manner.
[0034] In the example shown in FIG. 6, the hydraulic cylinder 42
may include a piston 56 that moves within the liquid chamber 52.
The liquid chamber 52 features an inlet 22 and an outlet 20. The
liquid chamber 52 is separated from an air chamber 54. The air
chamber 54 has an air inlet 58 and a vacuum inlet 60. (Although
these inlets are shown as two separate elements, there may be a
single inlet provided, and a control system may control the
application of vacuum or vent to the inlet.) In use, when the air
chamber 54 is evacuated by application of vacuum, the piston 56
moves to the right in FIG. 6. This pulls liquid into the water
inlet 22. (It should be understood that check valves may be
positioned at each of the inlets/outlets in order to maintain the
desired pressure across the vacuum inlet and the air inlet, as well
as to prevent backflow of fluid between the fluid inlet 22 and the
fluid outlet 20.)
[0035] When air is pushed into (or otherwise allowed to enter) the
air chamber 54, this creates a differential pressure that forces
the piston 56 to move to the left in FIG. 6, forcing liquid out of
the liquid chamber 52. For example, the air inlet 58 may have a
valve that can be opened to allow vent air to rush in when the
vacuum inlet 60 is closed via its valve. In this way, differential
pressure causes movement of the piston, which causes movement of
the liquid to be pumped.
[0036] The components of the pressure differential pump may
constructed of any material that can withstand varied environments
and pressures. One non-limiting example includes high-density
plastic polymers, such as Ultem or PEEK. There are no heavy
electromagnets or bearings required. The strength and low mass
benefits of these polymer materials provides a value to passenger
transport vehicles, where lightweight components can allow for
reduced fuel consumption or additional passenger revenue.
[0037] It is envisioned that the disclosed pumps may operate
on-board passenger transport vehicles such as watercraft vessels,
trains, aircraft, as well as other vehicles. The wide variance in
environmental conditions between these applications, such as
humidity, temperature, salt exposure, and so forth may guide
materials to be selected with possible the extremes in mind.
[0038] The fluids pumped by the device could vary widely based on
application. In one proposed application, potentially low
temperature fluids such as anti-freeze may be dosed and delivered
to appropriate system components. In this example, the materials
and mechanisms within the pump system 10 can be designed to
withstand low temperatures encountered by aircraft at altitude or a
train in winter, as well as be compatible to withstand various
types of applicable fluids. For example, if the pump system 10 is
used to pump potable water, materials with sufficient regulatory
certification may be chosen to ensure water quality. For example,
if the pump system 10 is used to pump grey water from a sink for
delivery to an on-board toilet for use as flushing water, the
materials may be chosen such that they can withstand various
detergents, bacteria and other microorganisms over a period of
time, and may have surfaces treated to withstand or discourage
undesired microbial growth. For example, if the pump system 10 is
used in medical or pharmaceutical applications, further increasing
regulatory requirements may dictate materials and size requirements
to be used.
[0039] It is understood that the present embodiments described may
be modified for the specific application such that the pump
fulfills the purpose of using differential pressure as the energy
source. Modifications within the scope of this disclosure can
include a different number of pistons, different reservoir shapes,
check valve placement and quantity variation, and material changes.
Changes and modifications, additions and deletions may be made to
the structures and methods recited above and shown in the drawings
without departing from the scope or spirit of the following
claims.
* * * * *