U.S. patent application number 11/793441 was filed with the patent office on 2008-12-11 for reaction drive energy transfer device.
This patent application is currently assigned to SubMachine Corp.. Invention is credited to Timothy S. Lucas.
Application Number | 20080304979 11/793441 |
Document ID | / |
Family ID | 36615424 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080304979 |
Kind Code |
A1 |
Lucas; Timothy S. |
December 11, 2008 |
Reaction Drive Energy Transfer Device
Abstract
A fluid energy transfer device, including a chamber for
receiving a fluid, at least a portion of the chamber comprising a
movable portion relative to another portion of the chamber, the
movable portion being adapted to change the volume of the chamber
from a first volume to a second volume by movement of the movable
portion. The device further includes a bender actuator attached to
the movable portion, wherein the bender actuator is at least one of
(i) connected directly to the movable portion and (ii) linked to
the movable portion, to form a bender-movable portion assembly,
wherein the bender is effectively not connected and effectively not
linked to any other component of the device other than the movable
portion, and wherein the bender-movable portion assembly is adapted
to move substantially only due to oscillation of the bender at a
drive frequency.
Inventors: |
Lucas; Timothy S.;
(Providence Forge, VA) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
SubMachine Corp.
|
Family ID: |
36615424 |
Appl. No.: |
11/793441 |
Filed: |
December 22, 2005 |
PCT Filed: |
December 22, 2005 |
PCT NO: |
PCT/US05/46557 |
371 Date: |
July 7, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60638195 |
Dec 23, 2004 |
|
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Current U.S.
Class: |
417/327 |
Current CPC
Class: |
F04B 45/04 20130101;
F04B 43/04 20130101; F04B 43/0054 20130101 |
Class at
Publication: |
417/327 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Claims
1. A fluid energy transfer device, comprising: a chamber for
receiving a fluid, at least a portion of the chamber comprising a
movable portion relative to another portion of the chamber, the
movable portion being adapted to change the volume of the chamber
from a first volume to a second volume by movement of the movable
portion; and a bender actuator attached to the movable portion;
wherein the bender actuator is at least one of (i) connected
directly to the movable portion and (ii) linked to the movable
portion, to form a bender-movable portion assembly; wherein the
bender is effectively not connected and effectively not linked to
any other component of the device other than the movable portion;
and wherein the bender-movable portion assembly is adapted to move
substantially only due to oscillation of the bender at a drive
frequency.
2. The device of claim 1, wherein the bender is connected to
electrical leads adapted to conduct electricity to the bender.
3. The device of claim 1, wherein the bender is resiliently
connected to a component of the device that is separate from the
movable portion.
4. The device of claim 1, wherein the bender is connected, via a
non-rigid connection, to a component of the device that is separate
from the movable portion.
5. The device of claim 1, wherein the bender actuator is adapted to
bend at a frequency such that the bender and moving portion will
move between a first position and a second position substantially
only due to the bending of the actuator, and wherein the distance
between the first position and the second position is substantially
greater than the distance of peak-to-peak bending of the
actuator.
6. The device of claim 1, wherein the bender actuator is adapted to
oscillate the movable portion at a frequency so as to store energy
in a system resonance of the device.
7. The device of claim 1, further comprising an axial stability
structure, wherein the axial stability structure is connected to
the bender-movable portion assembly and adapted to permit axial
movement of the bender-movable portion assembly and impeding
transverse movement of the bender-movable portion assembly.
8. The device of claim 1, further comprising a controller
operatively connected to the bender, wherein the controller is
adapted to vary the drive frequency in response to changes in a
system resonance frequency.
9. The device of claim 1, further comprising a controller adapted
to monitor performance of the device, wherein performance includes
at least one of flow rate of fluid exiting the device and fluid
pressure of fluid exiting through the device, wherein the
controller is also adapted to automatically vary a drive force of
the bender in response to the monitored performance of the
device.
10. The device of claim 9, wherein the controller is further
adapted to automatically change the drive force of the bender
actuator to automatically change a stroke distance of the movable
portion from a first stroke distance to a second stroke distance
different than the first stroke distance.
11. The device of claim 1, wherein the movable portion is a
diaphragm.
12. A fluid energy transfer device, comprising: a chamber for
receiving a fluid, at least a portion of the chamber comprising a
movable portion relative to another portion of the chamber, the
movable portion being adapted to change the volume of the chamber
from a first volume to a second volume; and a bender actuator
attached to the movable portion, wherein the bender actuator is at
least one of (i) connected directly to the movable portion and (ii)
linked to the movable portion, to form a bender-movable portion
assembly; wherein the bender actuator is adapted to bend at a
frequency such that the bender-diaphragm assembly will move between
the first position and the second position substantially due to
bending of the actuator; and wherein the distance between the first
position and the second position is at least one of greater than
and less than the distance of peak-to-peak bending of the
actuator.
13. The device of claim 12, wherein the distance between the first
position and the second position is at least about an order of
magnitude greater than the distance of peak-to-peak bending of the
actuator.
14. A fluidic system, comprising; the device according to claim 12;
and a fluid, at least a portion of which is present in the chamber;
wherein the bender actuator is adapted to be operable at a drive
frequency so as to store energy in a system resonance.
15. A fluidic system, comprising; the device according to claim 12;
and a fluid, at least a portion of which is present in the chamber;
wherein the device has a system resonance frequency governed by a
combined effective moving mass of mechanical components and the
fluid and a combined effective spring stiffness of the mechanical
components and the fluid; and wherein the bender actuator is
adapted to be operable at a drive frequency at or near the system
resonance frequency.
16. The device of claim 12 wherein the bender is effectively not
connected and effectively not linked to any other component of the
pump other than the movable portion.
17. A method of moving a fluid, comprising: providing a pump for
pumping a fluid, the pump comprising; a chamber for receiving a
fluid, at least a portion of the chamber comprising a movable
portion relative to another portion of the chamber, the movable
portion being adapted to change the volume of the chamber from a
first volume to a second volume by movement of the movable portion;
and a bender actuator attached to the movable portion; oscillating
the bender at a drive frequency so that forces are transmitted, in
reaction to the oscillations of the bender, to the movable portion,
causing the movable portion to be displaced in a manner such that a
displacement distance of the movable portion is at least one of
greater than or less than a peak-to-peak bending displacement of
the bender encountered during oscillation of the bender, and
drawing fluid into the chamber by moving the movable component to
increase the volume of the chamber.
18. The method of claim 17, further comprising oscillating the
bender at a frequency to obtain a displacement distance of the
movable portion that exceeds a maximum peak-to-peak bending
displacement of the bender encountered during oscillation of the
bender by at least about an order of magnitude.
19. The method of claim 17, further comprising oscillating the
bender at a drive frequency that is at least one of near and equal
to a system fundamental resonant frequency of the pump.
20. The method of claim 17, further comprising oscillating the
bender at a drive frequency so that forces are transmitted in
reaction to the oscillations of the bender to the movable portion
causing the movable portion to be displaced in a manner to store
energy in a system resonance to obtain a displacement distance of
the movable component that exceeds a maximum peak-to-peak bending
displacement of the bender encountered during oscillation of the
bender.
21. The method of claim 17, further comprising: opening an inlet to
the chamber and closing an outlet to the chamber; closing the inlet
to the chamber and opening the outlet to the chamber; wherein, to
draw fluid into the chamber, the action of opening the inlet to the
chamber and closing the outlet to the chamber is coordinated
temporally with a first movement of the movable portion that
increases the volume of the chamber; wherein, to direct fluid out
of the chamber, the action of closing the inlet to the chamber and
opening the outlet of the chamber is coordinated temporally with a
second movement of the movable portion that decreases the volume of
the chamber; wherein fluid flows into the chamber at least during a
portion of the time that the inlet is opened; and wherein fluid
flows out of the chamber at least during a portion of the time that
the outlet is opened.
22. The method of claim 17, wherein the bender actuator of the pump
is at least one of (i) connected directly to the movable portion
and (ii) linked to the movable portion, wherein the bender is
effectively not connected and effectively not linked to any other
component of the device other than the movable portion.
23. The method of claim 17, further comprising oscillating the
bender actuator to oscillate the movable portion at a frequency so
as to store energy in a system resonance of the pump.
24. The method of claim 22, wherein the bender is connected to
electrical leads adapted to conduct electricity to the bender.
25. The method of claim 22, wherein the bender is resiliently
connected to a component of the device that is separate from the
movable portion.
26. The method of claim 17, further comprising operating the bender
at a drive frequency so as to store energy in a system resonance of
the pump, the system resonance frequency being governed by a
combined effective moving mass of mechanical components and the
fluid and a combined effective spring stiffness of the mechanical
components and the fluid.
27. The method of claim 17, further comprising operating the bender
at a drive frequency at or near a system resonance frequency of the
pump.
28. A fluid energy transfer device, comprising: a chamber for
receiving a fluid, at least a portion of the chamber comprising a
movable portion relative to another portion of the chamber, the
movable portion being adapted to change the volume of the chamber
from a first volume to a second volume by movement of the movable
portion; and a bender actuator attached to the movable portion;
wherein the bender actuator is at least one of (i) connected
directly to the movable portion and (ii) linked to the movable
portion, to form a bender-movable portion assembly; wherein the
bender is at least one of (a) not rigidly connected and (b) not
rigidly linked to any other component of the device other than the
movable portion; and wherein the bender-movable portion assembly is
adapted to move substantially only due to oscillation of the bender
at a drive frequency.
29. A refrigerant system, comprising: a refrigerant compressor
including the device of claim 1; a condenser; a pressure drop
capillary tube; and an evaporator; wherein the refrigerant
compressor, the condenser, the pressure drop capillary tube, and
the evaporator are in a refrigerant loop.
30. A refrigerant system, comprising: a refrigerant compressor
including the device of claim 12; a condenser; and an evaporator;
wherein the refrigerant compressor, the condenser and the
evaporator are in a refrigerant loop.
31. A method of transferring heat, comprising: imparting movement
on and providing pressure lift to a refrigerant by executing the
method of claim 17, wherein the liquid is the refrigerant, to move
gaseous refrigerant from an evaporator to a condenser to condense
the refrigerant.
32. A pump, comprising: the device of claim 1; a fluid inlet port
in fluid communication with the chamber; and a fluid outlet port in
fluid communication with the chamber; wherein the device is adapted
to draw fluid into the chamber through the inlet port during
movement of the movable portion in a manner that increases the
volume of the chamber, and wherein the device is adapted to expel
fluid out of the chamber through the outlet port during movement of
the movable portion in a manner that decreases the volume of the
chamber.
33. A fluidic device, comprising: a synthetic jet, wherein the
synthetic jet includes the device of claim 1.
34. A pump, comprising: the device of claim 12; a fluid inlet port
in fluid communication with the chamber; and a fluid outlet port in
fluid communication with the chamber; wherein the device is adapted
to draw fluid into the chamber through the inlet port during
movement of the movable portion in a manner that increases the
volume of the chamber, and wherein the device is adapted to expel
fluid out of the chamber through the outlet port during movement of
the movable portion in a manner that decreases the volume of the
chamber.
35. A fluidic device, comprising: a synthetic jet, wherein the
synthetic jet includes the device of claim 12.
36. The device of claim 1, wherein, with the exception of
electrical leads, the bender is not connected to a component that
is separate from the movable portion.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/638,195, filed Dec. 23, 2004, the contents of
which are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1) Field of Invention
[0003] This invention relates generally to apparatus and methods
for conveying energy into a volume of fluid and more specifically
to the field of linear pumps, linear compressors, and other fluidic
devices.
[0004] 2) Description of Related Art
[0005] For the purpose of conveying energy to fluids within a
defined enclosure, prior technologies have employed a number of
approaches, including positive displacement, agitation such as with
mechanical stirring or the application of traveling or standing
acoustic waves, the application of centrifugal forces, and the
addition of thermal energy. The transfer of mechanical energy to
fluids by means of these various methods can be for a variety of
applications, which could include for example, compressing,
pumping, mixing, atomization, synthetic jets, fluid metering,
sampling, air testing for bio-warfare agents, ink jets, filtration,
or driving physical changes due to chemical reactions, or other
material changes in suspended particulates such as comminution or
agglomeration, or a combination of any of these processes, to name
a few.
[0006] Within the category of positive displacement machines,
diaphragms have found widespread use. The absence of frictional
energy losses makes diaphragms especially useful in downsizing
positive displacement machines while trying to maintain high energy
efficiency. The interest in MESO and MEMS scale devices has lead to
even further reliance on diaphragm-type devices for conveying
hydraulic energy into fluids within small pumps. The term "pump" as
used herein refers to devices designed for providing compression
and/or flow to either liquids or gases. The term "fluid" used
herein is understood to include both the liquid and the gaseous
states of matter.
[0007] The actuators used to drive larger diaphragm pumps have
proved problematic for MESO or MEMS machines since it is difficult
to maintain their efficiency and low cost as they are scaled down
in size. For example, the air gaps associated with electromagnetic
and voice coil type actuators must be scaled down in order to
maintain high transduction efficiency and this adds manufacturing
complexity and cost. Also, motor laminations become magnetically
saturated as motors are scaled down while seeking to maintain a
constant mechanical power output. Within acceptable product cost
targets, it is widely accepted that the electro-mechanical
efficiency of these transducers will drop off significantly with
size reduction.
[0008] These scaling challenges, associated with magnetic
actuators, have led to the widespread use of other technologies,
such as piezoceramics and magnetostrictive actuators, for MESO and
MEMS applications. A piezo disk naturally combines the fluid
diaphragm and actuator into a single component.
[0009] The advantages of using the piezo as the fluidic diaphragm
are offset by the piezo's inherent displacement limitations. Since
ceramics are relatively brittle, piezoceramic diaphragms/disks can
only provide a small fraction of the displacements provided by
other materials such as metals, plastics, and elastomers, for
example. The peak oscillatory displacements that a clamped circular
piezoceramic disk can provide without failure are typically less
than 1% of the disk's clamped diameter. Since diaphragm
displacement is directly related to the fluidic energy transferred
per stroke, piezos impose a significant limitation on the power
density and overall performance of small fluidic devices such as
MESO pumps and compressors. These displacement-related energy
limitations are especially true for gases.
[0010] Other types of piezo actuators that depend on the bulk
flexing properties of the piezo material can provide high energy
transfer to liquids by operating at very high frequencies, but at
even smaller strokes. These small actuator strokes make the design
of pumps impractical. Further, high-performance pumps employ
passive valves that open and close each pumping cycle to provide
optimal pumping efficiency. These pump valves may not provide the
needed performance in the kHz-MHz frequency range of the bulk-piezo
actuators.
[0011] Currently, the demand is increasing for ever smaller fluidic
devices which may not be attainable or functionally consistently
useful with current piezo pump technology. For example, pumps and
compressors are needed that can provide higher specific flow rates
(i.e. fluid volume flow rate divided by the pump's physical volume)
at higher pressure heads and in ever smaller sized units. Examples
of applications that require high performance MESO-sized pumps
include the miniaturization of fuel cells for portable electronic
devices such as portable computing devices, PDAs and cell phones,
self-contained thermal management systems that can fit on a circuit
card and provide cooling for microprocessors and other
semi-conductor electronics, and portable personal medical devices
for ambulatory patients. Thus, there is a need for a compact,
economically viable piezo pump that remedies at least some of the
deficiencies of current piezo pumps.
SUMMARY OF THE INVENTION
[0012] To satisfy these needs and overcome the limitations of
previous efforts, the present invention is provided as a fluid
energy-transfer device that uses a new reaction-drive actuator for
driving diaphragm fluidic devices, such as pumps and compressors,
at or near their system resonance. A fluidic energy transfer device
according to one embodiment comprises a fluid chamber having an
inner wall shaped so as to form a chamber volume with an opening
and a fluidic diaphragm being rigidly attached to the perimeter of
the opening and with a bender-type actuator being attachment to the
fluidic diaphragm. The reaction-drive energy-transfer device
according to some embodiments of the present invention provides a
unique system for driving displacements of the fluidic diaphragm
which can be an order of magnitude larger than the displacement of
prior piezo diaphragms.
[0013] The reaction-drive system according to most embodiments of
the present invention enables high-performance for devices such as
MESO-sized pumps and compressors and synthetic jets. The pumps and
compressors according to some embodiments of the present invention
may include tuned ports and valves that allow low-pressure fluid to
enter and high-pressure fluid to exit a compression chamber in
response to the cyclic compressions. The reaction-drive system may
use a variety of bender actuators, such as uni-morph, bi-morph and
multilayer PZT benders, piezo-polymer composites such as PVDF,
crystalline materials, magnetostrictive materials, electroactive
polymer transducers (EPTs), electrostrictive polymers and various
"smart materials" such as shape memory alloys (SMA), and radial
field PZT diaphragm (RFD) actuators.
[0014] The fluidic devices according to the present invention are
operated at a drive frequency that allows energy to be stored in
the system's mechanical resonance, thereby providing diaphragm
displacements that are larger and typically much larger that the
actual bending displacements of the bender-actuator. The system
resonance may be determined based on the effective moving mass of
the diaphragm, bender actuator and related components and on the
spring stiffness of the fluid, the fluidic diaphragm, and other
optional mechanical springs; and or other components/environments
that influence the resonant frequency.
[0015] The pumps according to some embodiments of the present
invention may be utilized in a variety of applications including by
way of example only the general compression of gases such as air,
hydrocarbons, process gases, high-purity gases, hazardous and
corrosive gases, with the compression of phase-change refrigerants
for refrigeration, air-conditioning and heat pumps with liquids,
and other specialty vapor-compression or phase-change heat transfer
applications. The pumps according to some embodiments of the
present invention may also pump liquids such as fuels, water, oils,
lubricants, coolants, solvents, hydraulic fluid, toxic or reactive
chemicals, depending on the particular pump design. The pumps of
the present invention can also provide variable capacity for either
gas or liquid operation.
[0016] More specifically, an exemplary embodiment of the present
invention includes a fluid chamber having an inner wall shaped so
as to form a chamber volume and having an opening. A fluidic
diaphragm is rigidly attached to the perimeter of the opening in
the fluid chamber and the diaphragm has a flexible portion capable
of moving with respect to the outer perimeter between a plurality
of first positions and a plurality of second positions, the first
and second positions being of varying distances from the inner wall
of the fluidic chamber. The chamber is filled with a fluid that
comprises part of the load of the system. The fluid within the
fluid chamber comprises a spring and the fluidic diaphragm also
comprises a spring. A bender actuator having an attachment point is
attached to the fluidic diaphragm. A mass-spring mechanical
resonance frequency is determined by the combined effective moving
masses of the bender actuator and fluidic diaphragm and by the
mechanical spring and the gas spring, and the bender actuator is
operable at a drive frequency so as to store energy in the
mass-spring mechanical resonance and provide displacements of the
fluidic diaphragm that are larger (and in many instances much
larger) than the bending displacements of the bender actuator, such
that increased energy is transferred to the fluidic load within the
fluid chamber.
[0017] In another embodiment of the invention, there is a fluid
energy transfer device comprising:
[0018] a fluid chamber adapted to receive a predetermined fluid,
the fluid chamber including a fluidic diaphragm rigidly attached to
structure of the fluid chamber substantially at the perimeter of
the diaphragm, wherein the diaphragm includes a flexible portion
adapted to move with respect to the perimeter attached to the
structure, between a first position and a second position; and
[0019] a bender actuator; wherein
[0020] the bender actuator is attached to the fluid diaphragm to
form a bender-diaphragm assembly;
[0021] wherein the bender actuator is adapted to bend at a
frequency such that the bender-diaphragm assembly will move between
the first position and the second position substantially only due
to the frequency of bending of the actuator, and
[0022] wherein the distance between the first position and the
second position is substantially greater than the distance of
peak-to-peak bending of the actuator, and is exemplary greater than
about an order of magnitude greater than the distance of
peak-to-peak bending.
[0023] In another embodiment of the invention, there is a fluid
energy transfer device comprising:
[0024] a fluid chamber adapted to receive a predetermined fluid,
the fluid chamber including a fluidic diaphragm rigidly attached to
structure of the fluid chamber substantially at the perimeter of
the diaphragm, wherein the diaphragm includes a flexible portion
adapted to move with respect to the attaching structure, between a
first position and a second position; and
[0025] a bender actuator;
[0026] wherein the bender actuator is at least one of (i) connected
directly to the fluid diaphragm and (ii) directly linked to the
fluid diaphragm,
[0027] wherein the bender is effectively not connected and
effectively not linked to any other component of the pump other
than the diaphragm, and
[0028] wherein the bender is optionally connected to electrical
leads adapted to conduct electrons to the bender.
[0029] In another embodiment of the present invention, there is a
fluid energy transfer device comprising:
[0030] a fluid chamber having an inner wall shaped so as to form a
chamber volume and having an opening;
[0031] a fluidic diaphragm being rigidly attached to the perimeter
of the opening in the fluid chamber and the diaphragm having a
flexible portion capable of moving with respect to the outer
perimeter between a plurality of first positions and a plurality of
second positions, the first and second positions being of varying
distances from the inner wall of the fluidic chamber;
[0032] a fluid within the fluid chamber;
[0033] a fluid spring comprising the fluid within the fluidic
chamber;
[0034] a mechanical spring comprising the diaphragm;
[0035] a bender actuator having an attachment point being attached
to the fluidic diaphragm;
[0036] wherein a mass-spring mechanical resonance frequency is
determined by the combined effective moving masses of the bender
actuator and the diaphragm and by the mechanical spring and the gas
spring, and wherein the bender actuator is operable at a drive
frequency so as to store energy in the mass-spring mechanical
resonance thereby transferring energy to the fluid within the fluid
chamber.
[0037] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
attachment point of the bender actuator to the fluidic diaphragm
comprises the power take-off point and wherein a reaction mass is
attached to a point on the bender actuator that moves with opposite
time phase than the power take off point.
[0038] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
attachment point between the bender actuator and the fluidic
diaphragm further comprises a tuning spring such that the forces
created by the bender actuator are transmitted through the tuning
spring to the fluidic diaphragm and wherein the stiffness of the
tuning spring is chosen so as to improve the mechanical power
factor.
[0039] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein a
first point of an axial stability member is attached to a standoff
with the other end of the standoff being attached to a moving
portion of the fluidic diaphragm and a second point of the axial
stability component being attached to the exterior of the fluid
chamber, whereby the axial stability component is axially offset
from the plane of the fluidic diaphragm thereby allowing axial
movement of the moving masses but impeding transverse movement of
the moving masses.
[0040] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
bender actuator comprises a piezoceramic bender actuator.
[0041] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
bender actuator comprises a piezo-polymer composite bender
actuator.
[0042] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
bender actuator comprises a magnetostrictive bender actuator.
[0043] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
bender actuator comprises a radial field PZT diaphragm bender
actuator.
[0044] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
wall of the fluid chamber further comprise a synthetic jet port
which fluidically communicates the interior of the fluid chamber to
the exterior of the fluid chamber, whereby the pressure within the
fluid chamber oscillates at the drive frequency thereby creating a
synthetic jet outside the fluid chamber causing fluid to flow away
from the fluid chamber along the cylindrical axis of the synthetic
jet port.
[0045] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, further
comprising:
[0046] an inlet port being connected in communication with the
fluid chamber for flowing a fluid into the fluid chamber;
[0047] an outlet port being connected in communication with the
fluid chamber for flowing a fluid out of the fluid chamber.
[0048] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
inlet port has a flow rectifying profile designed to provide flow
into the fluid chamber and the outlet port has a flow rectifying
profile designed to provide flow into the fluid chamber;
[0049] whereby the displacements of the fluidic diaphragm create
pressure oscillations within the fluid at the drive frequency
thereby causing fluid to flow into the fluid chamber through the
inlet port and flow out of the fluid chamber through the outlet
port.
[0050] In another embodiment of the present invention, there is a
fluid transfer device as described above and/or below, wherein the
bender actuator comprises a piezoceramic bender actuator.
[0051] In another embodiment of the present invention, there is a
pump comprising:
[0052] a fluid chamber having an inner wall shaped so as to form a
chamber volume and having an opening;
[0053] a fluidic diaphragm being rigidly attached to the perimeter
of the opening in the fluid chamber and the fluidic diaphragm
having a flexible portion capable of moving with respect to the
outer perimeter between a plurality of first positions and a
plurality of second positions, the first and second positions being
of varying distances from the inner wall of the fluidic
chamber;
[0054] an inlet port being connected in communication with the
fluid chamber for flowing a fluid into the fluid chamber;
[0055] an outlet port being connected in communication with the
fluid chamber for flowing a fluid out of the fluid chamber;
[0056] a fluid within the fluid chamber;
[0057] a fluid spring comprising the fluid within the fluid
chamber;
[0058] a mechanical spring comprising the diaphragm;
[0059] a bender actuator having an attachment point being attached
to the fluidic diaphragm;
[0060] wherein a mass-spring mechanical resonance frequency is
determined by the combined effective moving masses of the bender
actuator and the diaphragm and by the mechanical spring and the gas
spring, and wherein the bender actuator is operable at a drive
frequency so as to store energy in the mass-spring mechanical
resonance thereby transferring energy to the fluid within the fluid
chamber.
[0061] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the attachment point
of the bender actuator to the fluidic diaphragm comprises the power
take-off point and wherein a reaction mass is attached to a point
on the bender actuator that moves with a different time phase than
the power take off point.
[0062] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the attachment point
between the bender actuator and the fluidic diaphragm further
comprises a tuning spring such that the forces created by the
bender actuator are transmitted through the tuning spring to the
fluidic diaphragm and wherein the stiffness of the tuning spring is
chosen so as to improve the mechanical power factor.
[0063] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein a first point of an
axial stability member is attached to a standoff with the other end
of the standoff being attached to a moving portion of the fluidic
diaphragm and a second point of the axial stability component being
attached to the exterior of the fluid chamber, whereby the axial
stability component is axially offset from the plane of the fluidic
diaphragm, thereby allowing axial movement of the moving masses but
impeding transverse movement of the moving masses.
[0064] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the bender actuator
comprises a piezoceramic bender actuator.
[0065] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the bender actuator
comprises a piezo-polymer composite bender actuator.
[0066] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the bender actuator
comprises a magnetostrictive bender actuator.
[0067] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the bender actuator
comprises a radial field PZT diaphragm bender actuator.
[0068] In another embodiment of the present invention, there is a
pump as described above and/or below, further comprising control
means operatively connected with the bender actuator for varying
the drive frequency in response to changes in the mass-spring
mechanical resonance frequency.
[0069] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the drive frequency
is equal to the mass-spring mechanical resonance frequency.
[0070] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the control means
further comprises:
[0071] a means for measuring selected operating conditions in the
pump;
[0072] means for varying the drive frequency of the motor in
response to the measured operating conditions in order to maximize
the measured operating conditions.
[0073] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the operating
conditions comprises the electrical power delivered to the
pump.
[0074] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluid is a
gas.
[0075] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the gas is selected
from the group consisting of air, hydrocarbons, process gases,
high-purity gases, hazardous and corrosive gases toxic fluids,
high-purity fluids, reactive fluids and environmentally hazardous
fluids.
[0076] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluid is a
liquid.
[0077] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the liquid is
selected from the group consisting of fuels, water, oils,
lubricants, coolants, solvents, hydraulic fluid, toxic or reactive
chemicals.
[0078] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first positions
of the fluidic diaphragm are proximal to the wall of the fluid
chamber at the top of respective compression strokes, and the
second positions are distal to the wall of the fluid chamber at the
end of respective inlet strokes, and where the first and second
proximal positions are at different distances from the wall of the
fluid chamber and where the first and second distal positions are
at different distance from the wall of the fluid chamber, and
wherein the diaphragm is operably movable from oscillating between
first proximal and distal positions to oscillating between second
proximal and distal positions in response to changing the drive
force of the bender actuator.
[0079] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein changing the drive
force of the bender actuator operably moves the diaphragm from
oscillating between first proximal and distal positions to
oscillating between second proximal and distal positions and
thereby provides a change in the flow rate of the fluid.
[0080] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the inlet port has a
flow rectifying profile designed to provide flow into the fluid
chamber and the outlet port has a flow rectifying profile designed
to provide flow into the fluid chamber;
[0081] whereby the displacements of the fluidic diaphragm create
pressure oscillations within the fluid at the drive frequency
thereby causing fluid to flow into the fluid chamber through the
inlet port and flow out of the fluid chamber through the outlet
port.
[0082] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the pump further
comprises an inlet valve operatively connected to the inlet port
and an outlet valve operatively connected to the outlet port, the
inlet valve and the outlet valve each having a predetermined
stiffness and a valve duty cycle, wherein the inlet valve prevents
flow through the inlet port in a closed position and allows flow
through the inlet port in an open position and the outlet valve
prevents flow through the outlet port in a closed position and
allows flow through the outlet port in an open position, and
wherein the stiffness and size of the outlet valve and the inlet
valve each being selected to tune the inlet valve and outlet valve
such that the timing of the duty cycles of the inlet valve and the
outlet valve are coordinated with the timing of the filling of
fluid flow and/or the fluid flow through the inlet port and the
discharge of the fluid flow through the outlet port and the
pressure cycle in the compression chamber to provide a net flow in
one direction of the fluid within the pump.
[0083] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the inlet valve is a
reed valve and the outlet valve is a reed valve.
[0084] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the inlet reed valve
and the outlet reed valve each has a spring stiffness and mass
adapted to open and close in proper sequence in response to the
oscillating fluid pressure within the fluid chamber, whereby proper
valve timing is maintained without valve stops.
[0085] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluidic diaphragm
further comprises a flat section that moves in planar fashion and
wherein the inlet ports and inlet valves are located on the flat
section of the diaphragm, thereby providing actuation for the inlet
valves.
[0086] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluidic diaphragm
further comprises a flat section that moves in planar fashion and
wherein the outlet ports and outlet valves are located on the flat
section of the diaphragm, thereby providing actuation for the
outlet valves.
[0087] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the pump further
comprises:
[0088] a plurality of inlet ports being connected in communication
with the fluid chamber for flowing a fluid into the fluid
chamber;
[0089] a plurality of outlet ports being connected in communication
with the fluid chamber for flowing a fluid out of the fluid
chamber.
[0090] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the wall of the fluid
chamber further comprises a radially contoured wall section, and
the flexible portion of the diaphragm being free to flex to
generally conform in shape to the radially contoured section for
minimizing clearance volume in the fluid chamber as the moving
portion cycles to the plurality of first positions.
[0091] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluidic diaphragm
further includes a first face within the fluid chamber and a second
face outside of an interior of the fluid chamber, and wherein the
pump further comprises an exterior chamber in fluid communication
with the second face of the diaphragm, a hole extending between and
in communication with the fluid chamber and the exterior chamber
with the hole having a geometry sized and selected to communicate a
sufficient quantity of fluid through the hole between the fluid
chamber and the exterior chamber for equalizing pressure on the
first and second faces of the diaphragm.
[0092] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the hole is
positioned in the diaphragm.
[0093] In another embodiment of the present invention, there is a
pump comprising:
[0094] a fluid chamber having an inner wall shaped so as to form a
chamber volume and having a first and second opening;
[0095] a first fluidic diaphragm being rigidly attached to the
perimeter of the first opening in the fluid chamber and the first
fluidic diaphragm having a flexible portion capable of moving with
respect to the outer perimeter between a plurality of first
positions and a plurality of second positions, the first and second
positions being of varying distances from the inner wall of the
fluidic chamber;
[0096] a second fluidic diaphragm being rigidly attached to the
perimeter of the first opening in the fluid chamber and the second
fluidic diaphragm having a flexible portion capable of moving with
respect to the outer perimeter between a plurality of first
positions and a plurality of second positions, the first and second
positions being of varying distances from the inner wall of the
fluidic chamber;
[0097] at least one inlet port being connected in communication
with the fluid chamber for flowing a fluid into the fluid
chamber;
[0098] at least one outlet port being connected in communication
with the fluid chamber for flowing a fluid out of the fluid
chamber;
[0099] a fluid within the fluid chamber;
[0100] a fluid spring comprising the fluid within the fluid
chamber;
[0101] a first mechanical spring comprising the first
diaphragm;
[0102] a second mechanical spring comprising the second
diaphragm;
[0103] a first bender actuator having a first attachment point
being attached to the first fluidic diaphragm;
[0104] a second bender actuator having a second attachment point
being attached to the second fluidic diaphragm;
[0105] wherein a mass-spring mechanical resonance frequency is
determined by the combined effective moving masses of the first
bender actuator and the first diaphragm and by the first mechanical
spring and the gas spring and also by the combined effective moving
masses of the second bender actuator and the second diaphragm and
by the second mechanical spring and the gas spring, and wherein the
first and second bender actuators are operable at the same drive
frequency so as to cause both first and second diaphragms to
simultaneously traverse their respective compression and outlet
strokes, thereby storing energy in the mass-spring mechanical
resonance and transferring energy to the fluid within the fluid
chamber.
[0106] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the attachment point
of the first bender actuator to the first fluidic diaphragm
comprises the first power take-off point and wherein a first
reaction mass is attached to a point on the first bender actuator
that moves with a different time phase than the first power take
off point, and wherein the attachment point of the second bender
actuator to the second fluidic diaphragm comprises the second power
take-off point and wherein a second reaction mass is attached to a
point on the second bender actuator that moves with a different
time phase than the second power take off point.
[0107] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first attachment
point between the first bender actuator and the first fluidic
diaphragm further comprises a first tuning spring such that the
forces created by the first bender actuator are transmitted through
the first tuning spring to the first fluidic diaphragm and wherein
the stiffness of the first tuning spring is chosen so as to improve
the mechanical power factor of the first bender actuator, and
wherein the second attachment point between the second bender
actuator and the second fluidic diaphragm further comprises a
second tuning spring such that the forces created by the second
bender actuator are transmitted through the second tuning spring to
the second fluidic diaphragm and wherein the stiffness of the
second tuning spring is chosen so as to improve the mechanical
power factor of the second bender actuator.
[0108] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein a first point of a
first axial stability member is attached to a first standoff with
the other end of the first standoff being attached to a moving
portion of the first fluidic diaphragm and a second point of the
first axial stability component being attached to the exterior of
the fluid chamber, and wherein a first point of a second axial
stability member is attached to a second standoff with the other
end of the second standoff being attached to a moving portion of
the second fluidic diaphragm and a second point of the second axial
stability component being attached to the exterior of the fluid
chamber,
[0109] whereby the first and second axial stability components are
axially offset from the plane of their respective first and second
fluidic diaphragms, thereby allowing axial movement of the moving
masses but impeding transverse movement of the moving masses.
[0110] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first bender
actuator comprises a piezoceramic bender actuator and the second
bender actuator comprises a piezoceramic bender actuator.
[0111] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first bender
actuator comprises a piezo-polymer composite bender actuator and
the second bender actuator comprises a piezo-polymer composite
bender actuator.
[0112] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first bender
actuator comprises a magnetostrictive bender actuator and the
second bender actuator comprises a magnetostrictive bender
actuator.
[0113] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first bender
actuator comprises a radial field PZT diaphragm bender actuator and
the second bender actuator comprises a radial field PZT diaphragm
bender actuator.
[0114] In another embodiment of the present invention, there is a
pump as described above and/or below, further comprising control
means operatively connected with the first and second bender
actuators for varying the drive frequency in response to changes in
the mass-spring mechanical resonance frequency.
[0115] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the drive frequency
is equal to the mass-spring mechanical resonance frequency.
[0116] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the control means
further comprises:
[0117] a means for measuring selected operating conditions in the
pump;
[0118] means for varying the drive frequency of the motor in
response to the measured operating conditions in order to maximize
the measured operating conditions.
[0119] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the operating
conditions comprises the electrical power delivered to the
pump.
[0120] In another embodiment of the present invention, there is a
pump as described above and/or below, further comprising control
means operatively connected with the first and second bender
actuators for varying the individual drive voltage amplitudes of
first and second bender actuators as needed to minimize the
vibration of the pump.
[0121] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluid is a
gas.
[0122] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the gas is selected
from the group consisting of air, hydrocarbons, process gases,
high-purity gases, hazardous and corrosive gases toxic fluids,
high-purity fluids, reactive fluids and environmentally hazardous
fluids.
[0123] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the fluid is a
liquid.
[0124] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the liquid is
selected from the group consisting of fuels, water, oils,
lubricants, coolants, solvents, hydraulic fluid, toxic or reactive
chemicals.
[0125] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first positions
of the first and second fluidic diaphragms are proximal to the wall
of the fluid chamber at the top of respective compression strokes,
and the second positions are distal to the wall of the fluid
chamber at the end of respective inlet strokes, and where the first
and second proximal positions are at different distances from the
wall of the fluid chamber and where the first and second distal
positions are at different distances from the wall of the fluid
chamber, and wherein the first and second fluidic diaphragms are
operably movable from oscillating between first proximal and distal
positions to oscillating between second proximal and distal
positions in response to changing the drive forces of the first and
second bender actuators.
[0126] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein changing the drive
force of the first and second bender actuators operably moves the
first and second fluidic diaphragms from oscillating between first
proximal and distal positions to oscillating between second
proximal and distal positions and thereby provides a change in the
flow rate of the fluid.
[0127] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the inlet port has a
flow rectifying profile designed to provide flow into the fluid
chamber and the outlet port has a flow rectifying profile designed
to provide flow into the fluid chamber;
[0128] whereby the displacements of the first and second fluidic
diaphragms create pressure oscillations within the fluid at the
drive frequency thereby causing fluid to flow into the fluid
chamber through the inlet port and flow out of the fluid chamber
through the outlet port.
[0129] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the pump further
comprises an inlet valve operatively connected to the inlet port
and a outlet valve operatively connected to the outlet port, with
the inlet valve and outlet valve each having a predetermined
stiffness and a valve duty cycle, wherein the inlet valve prevents
flows through the inlet port in a closed position and allows flow
through the inlet port in an open position and the outlet valve
prevents flow through the outlet port in a closed position and
allows flow through the outlet port in an open position, and
wherein the stiffness and size of the outlet valve and the inlet
valve each being selected to tune the inlet valve and outlet valve
such that the timing of the duty cycles of the inlet valve and the
outlet valve are coordinated with the timing of the filling of
fluid flow through the inlet port and the discharge of the fluid
flow through the outlet port and the pressure cycle in the
compression chamber to provide a net flow in one direction of the
fluid within the pump.
[0130] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the inlet valve is a
reed valve and the outlet valve is a reed valve.
[0131] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the inlet reed valve
and the outlet reed valve each has a spring stiffness and mass
adapted to open and close in proper sequence in response to the
oscillating fluid pressure within the fluid chamber, whereby proper
valve timing is maintained without valve stops.
[0132] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the first fluidic
diaphragm further comprises a first flat section that moves in a
planar fashion and the second fluidic diaphragm further comprises a
second flat section that moves in planer fashion and wherein the
inlet ports and inlet valves are located on the first flat section
of the first diaphragm the outlet ports and outlet valves are
located on the second flat section of the second diaphragm, thereby
providing actuation for the inlet valves and the outlet valves.
[0133] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the pump further
comprises:
[0134] a plurality of inlet ports being connected in communication
with the fluid chamber for flowing a fluid into the fluid
chamber;
[0135] a plurality of outlet ports being connected in communication
with the fluid chamber for flowing a fluid out of the fluid
chamber.
[0136] In another embodiment of the present invention, there is a
pump as described above and/or below, wherein the wall of the fluid
chamber further comprises a radially contoured wall section, and
the flexible portion of the first and second fluidic diaphragms
being free to flex and to generally conform in shape to the
radially contoured section for minimizing clearance volume in the
fluid chamber as the moving portions of first and second fluidic
diaphragms cycle to the plurality of first positions.
[0137] In another embodiment of the present invention, there is a
method of pumping a fluid comprising:
[0138] providing a pump for compressing a fluid, the pump
comprising;
[0139] a fluid chamber having an inner wall shaped so as to form a
chamber volume and having an opening;
[0140] a fluidic diaphragm being rigidly attached to the perimeter
of the opening in the fluid chamber and the fluidic diaphragm
having a flexible portion capable of moving with respect to the
outer perimeter between a plurality of first positions and a
plurality of second positions, the first and second positions being
of varying distances from the inner wall of the fluidic
chamber;
[0141] an inlet port being connected in communication with the
fluid chamber for flowing a fluid into the fluid chamber;
[0142] an outlet port being connected in communication with the
fluid chamber for flowing a fluid out of the fluid chamber;
[0143] a fluid within the fluid chamber;
[0144] a fluid spring comprising the fluid within the fluid
chamber;
[0145] a mechanical spring comprising the diaphragm;
[0146] a bender actuator having an attachment point being attached
to the fluidic diaphragm; the method further comprising:
[0147] introducing a fluid into the fluid chamber at a first
pressure, wherein the fluid acts as a fluid spring under varying
pressure conditions;
[0148] determining a mass-spring mechanical resonance frequency by
the combined moving masses of the diaphragm and bender actuator and
by the mechanical spring and the fluid spring;
[0149] operating the bender actuator at a drive frequency so as to
store energy in the mass-spring mechanical resonance;
[0150] oscillating the diaphragm between the plurality of first
positions and second positions;
[0151] compressing the fluid to a desired second pressure; and
[0152] evacuating the fluid from the compression chamber at the
second pressure.
[0153] In another embodiment of the invention, there is a fluid
energy transfer device comprising:
[0154] a fluid chamber for receiving a specific fluid having an
inner wall shaped so as to form a chamber volume and having an
opening;
[0155] a fluidic diaphragm being rigidly attached to the perimeter
of the opening in the fluid chamber and the diaphragm having a
flexible portion capable of moving with respect to the outer
perimeter between a plurality of first positions and a plurality of
second positions, the first and second positions being of varying
distances from the inner wall of the fluidic chamber;
[0156] a bender actuator having an attachment point being attached
to the fluid diaphragm;
[0157] wherein a mass-spring mechanical resonance frequency is
determined by the combined effective moving mass and the combined
effective spring stiffness of the dynamic components and specific
fluid and wherein the bender actuator is operable at a drive
frequency so as to store energy in the mass-spring mechanical
resonance.
[0158] In another embodiment of the invention, there is a fluidic
energy transfer device comprising:
[0159] a fluid chamber having an inner wall shaped so as to form a
chamber volume and having an opening;
[0160] a fluidic diaphragm being rigidly attached to the perimeter
of the opening in said fluid chamber and the diaphragm having a
flexible portion capable of moving with respect to the outer
perimeter between a plurality of first positions and a plurality of
second positions, the first and second positions being of varying
distances from the inner wall of the fluidic chamber;
[0161] a fluid within the fluidic chamber;
[0162] a fluidic load comprising said fluid;
[0163] a fluid spring comprising the fluid within said fluidic
chamber;
[0164] a mechanical spring comprising said diaphragm; and
[0165] a bender actuator having an attachment point being attached
to said fluidic diaphragm;
[0166] wherein a mass-spring mechanical resonance frequency is
determined by the combined effective moving masses of said bender
actuator and said diaphragm and by said mechanical spring and said
gas spring, and wherein the bender actuator is operable at a drive
frequency so as to store energy in the mass-spring mechanical
resonance and provide displacements of the fluidic diaphragm that
are larger than the bending displacements of the bender actuator,
and wherein energy is transferred to the fluidic load within the
fluid chamber.
[0167] In another embodiment of the invention, there is a fluid
energy transfer device comprising:
[0168] a fluid chamber adapted to receive a predetermined fluid,
the fluid chamber including a fluidic diaphragm rigidly attached to
structure of the fluid chamber substantially at the perimeter of
the diaphragm, wherein the diaphragm includes a flexible portion
adapted to move with respect to the perimeter attached to the
structure, between a first position and a second position;
[0169] a bender actuator; wherein
[0170] the bender actuator is attached to the fluid diaphragm to
form a bender-diaphragm assembly;
[0171] wherein the bender actuator is adapted to bend at a
frequency such that the bender-diaphragm assembly will move between
the first position and the second position substantially only due
to the frequency of bending of the actuator, and
[0172] wherein the distance between the first position and the
second position is substantially greater than the distance of
peak-to-peak bending of the actuator, and is exemplary about an
order of magnitude greater than the distance of peak-to-peak
bending.
BRIEF DESCRIPTION OF THE DRAWINGS
[0173] The accompanying drawings, which are incorporated in and
form a part of the specification, illustrate the embodiments of the
present invention and, together with the description, serve to
explain the principles of the inventions. In the drawings:
[0174] FIG. 1 is a cross sectional view of an embodiment of the
reaction-drive system of the current invention with a schematic
illustration of a bender disk in a non-deflected state;
[0175] FIG. 2 is a cross-sectional view of a bender actuator that
illustrates the deflection shape of the bender disk in response to
an alternating voltage waveform;
[0176] FIG. 3 is a cross-sectional view an embodiment of the
present invention having a reaction mass that may improve
mechanical power transfer from the bender disk;
[0177] FIG. 4 is a cross-sectional view an embodiment of the
present invention having an elliptical tuning spring that may
improve the mechanical power factor of the bender actuator;
[0178] FIG. 5 is a cross-sectional view an embodiment of the
present invention having a disk tuning spring that may improve the
mechanical power factor of the bender actuator;
[0179] FIG. 6 is a cross-sectional view an embodiment of the
present invention having an axial alignment disk that may improve
axial stability;
[0180] FIG. 6a is a cross-sectional view an another embodiment of
the present invention;
[0181] FIG. 7 is a cross-sectional view of a reaction-drive pump
embodiment of the present invention;
[0182] FIG. 8 is a cross-sectional view of a reaction-drive pump
embodiment of the present invention providing refrigerant
compression and flow in a closed-loop vapor-compression heat
transfer system;
[0183] FIG. 9 is a cross-sectional view of a reaction-drive pump
embodiment of the present invention that provides reduced clearance
volume;
[0184] FIG. 10 is a cross-sectional view of a reaction-drive pump
embodiment of the present invention with an increased diameter of
the diaphragm standoff, where the diaphragm is more piston-like in
its displacement as compared to the embodiment of FIG. 1, and to
further reduce clearance volume;
[0185] FIG. 11 is a cross-sectional view of a reaction-drive pump
embodiment of the present invention that reduces pump size and
provides valve actuation by locating the inlet valve on the fluidic
diaphragm;
[0186] FIG. 12 is a cross-sectional view of a reaction-drive pump
embodiment of the present invention that drives two fluidic
diaphragms in opposition, thus, in some embodiments minimizing the
forces transmitted to the pump housing via force cancellation and
reducing pump vibration;
[0187] FIG. 13 provides a block diagram of a drive circuit having a
resonance controller for use with the pumps of some of the
embodiments of the present invention;
[0188] FIG. 14 provides a block diagram of a dual-diaphragm drive
circuit having a resonance controller and a control for balancing
the diaphragm drive forces;
[0189] FIG. 15 is a cross-sectional view of a synthetic-jet
embodiment of the present invention.
DETAILED DESCRIPTION OF SOME EMBODIMENTS
[0190] Referring now to FIG. 1, there is illustrated a
cross-sectional view of one embodiment of the reaction-drive system
of the present invention. A cylindrical fluid-filled cavity 2 is
bounded by enclosure 4 and circular diaphragm 6. Diaphragm 6 is
held around its perimeter between O-ring 8 and O-ring 10 being
clamped into enclosure 4 by threaded clamp ring 11. Standoff 12 is
rigidly connected to the center of diaphragm 6 with the other end
of standoff 12 being rigidly connected to the center of
bender-actuator disk 14. These component connections may be made
with adhesive, brazing, or other types of low-profile bonding
processes. In most embodiments of the present invention, the bender
disk 14 has no other mechanical connections other than to stand-off
12 so that its perimeter is free of any mechanical constraint.
However, in other embodiments, a mechanical connection may be
present providing that the connection does not substantially
interfere with operation of the reaction-drive system at a drive
frequency that allows energy to be stored in the system's
mechanical resonance to provide desired diaphragm or piston
displacements. Electrical wires 15 serve to attach bender disk 14
to an external voltage source and are mechanically resilient in
nature being constructed for example of thin wire, braided wire or
thin metal strips. Wire attachment points to the piezo disk may
vary based on the type of piezo bender. To minimize
vibration-related stresses on wires 15, the wires could be routed
back to enclosure 4 (mechanical ground) by insulating and bonding
the wires to bender 14, standoff 12, and then from the center of
diaphragm 6 out to enclosure 4. In this way the wires would be
mechanically supported along their entire path. When energized by
an applied voltage, bender disk 14 bends into an axi-symmetric dome
as shown in FIG. 2, where deflective shapes 16 and 18 illustrate
how bender disk 14 bends in response to voltages of opposite
polarity. Deflections 16 and 18 are exaggerated for clarity.
[0191] In operation, an alternating voltage waveform of frequency f
is applied to bender disk 14 of FIG. 1 causing it to oscillate at
frequency f between the bending deflections 16 and 18 of FIG. 2. As
bender disk 14 oscillates between deflections 16 and 18 at
frequency f forces will be transmitted in reaction to the
deflections to diaphragm 6 through standoff 12, thus causing
diaphragm 6 to also oscillate at frequency f between the two
extremes of its fundamental displacement mode, thereby transferring
energy to the fluid within cavity 2. In the embodiment of FIG. 1,
the power-take-off (PTO) point from bender disk 14 is at the center
of bender disk 14. The reaction-drive fluidic system of FIG. 1 may
have a mechanical resonance frequency
f.sub.o=(1/2.pi.)(K/M).sup.1/2 where K=the combined stiffness of
the mechanical and fluidic springs, M=the combined effective moving
mass of diaphragm 6, standoff 12 and bender actuator 14, and
f.sub.o refers to the system resonance frequency that results in
the clamped fluidic diaphragm 6 oscillating in its lowest ordered
mode shape. Lumped element mechanical and electrical analogue
numerical models and other models may be used to predict/estimate
the fundamental resonance frequency of the fluidic system of FIG.
1. It is further understood that diaphragm 6 may not respond in its
fundamental mode if the drive frequency f is in excess of the
fundamental system resonance frequency f.sub.o, due to excitation
of other modes in the system's combined modal spectrum. Exciting
these higher-ordered modes may be less effective and in some
instances much less effective in transferring net energy to the
fluid, since portions of the diaphragm may be moving with opposite
phases, thus reducing net energy transfer due to cancellation.
[0192] If a drive frequency f is chosen to be near or equal to the
system's fundamental resonant frequency f.sub.o, then energy may be
stored in the oscillation in proportion to the system's resonance
quality factor Q at the drive frequency f. As energy is stored in
the system's resonance, the displacement of diaphragm 6 can exceed
the actual bending displacements of bender disk 8. In this way, a
low-displacement bender disk actuator may be used to provide the
higher diaphragm displacements required by current MESO and MEMS
fluidics applications. Since the only substantial (or otherwise
effective) mechanical connection to bender disk 14 of FIG. 1 is to
standoff 12, bender disk 14 is free to ride along with the larger
displacements of diaphragm 6, even when the bending amplitudes 16
and 18 of piezo disk 14 remain only a fraction of the flexing
amplitude of diaphragm 6.
[0193] For example, a system similar to that depicted in FIG. 1 was
tested that used a 25.4 mm diameter piezo bender disk, a 3.5 mil
thick diaphragm having a 32 mm clamped diameter and made of
"flapper valve" steel, and with the height of fluid-filled cavity 2
being 60 mil. The fluid used was air at 1 atmosphere. Even though
the piezo disk could only provide peak-to-peak flexing
displacements of 0.20 mm without failure, when installed in the
reaction-drive system, it was able to drive peak-to-peak diaphragm
displacements of over 3.0 mm. This reaction-drive system thus
allowed the fluidic diaphragm to experience displacements that were
15.times. greater than the piezo bender displacement. Depending on
the tuning of the system, displacement amplifications higher and
even much higher than 15.times. may be provided, as well as
amplifications that are lower and even much lower than 15.times..
The resonant displacement-amplification of a bender actuator
comprises the characteristic dynamics of the present invention and
is referred to herein as "reaction-drive."
[0194] Embodiments of the reaction-drive system are simple and
robust requiring relatively little precision in assembly. In
embodiments driven by bender actuators, there are no air gaps
associated with electromagnetic and voice-coil type actuators, and
the system is tolerant of non-axial oscillations.
[0195] As a result of using an unclamped bender actuator (or an
effectively unclamped bender actuator) to drive a separate fluidic
diaphragm, the bender actuator may be effectively considered a
force source as opposed to a displacement source. Many different
piezo bender shapes and topologies can be used within the scope of
most embodiments of the present invention. For example, uni-morph
and bi-morphs benders having rectangular, square, polygon symmetry
may be used in some embodiments of the present invention. Bender
actuator designs may be optimized for use in some embodiments of
the present invention by considering the tradeoffs among bender
characteristics such as actuator material, stiffness, mass, mass
distribution, force output, and the bender's mechanical resonance
frequency. Also, any bender that undergoes bending deflections in
response to an applied voltage may be used with the reaction-drive
system of most embodiments of the present invention. Uni-morph,
bi-morph and multilayer benders can be constructed from a number of
different classes of ceramics, piezo-polymer composites such as
PVDF, crystalline materials, magnetostrictive materials,
electroactive polymer transducers (EPTs), electrostrictive polymers
and various "smart materials" such as shape memory alloys (SMA)
actuators made from materials such as Nitinol, could be used for
example. Another class of PZT bender is a radial field PZT
diaphragm (RFD) which could also be employed in the present
invention. In summary, any material that bends in response to the
cyclic application of energy could almost certainly be employed as
a bender in the reaction-drive system within the scope of the
current invention and is collectively referred to as a "bender
actuator" herein.
Reaction-Drive System Tuning
[0196] In most embodiments of the present invention, tuning of the
system components is performed to vary (e.g., increase/maximize)
the power transferred from the bender actuator to the fluidic load
and to vary the power transfer efficiency. For a given bender
actuator, the power delivered to the fluid load may be optimized in
a number of ways. In such embodiments, the system resonance
typically should be within the useful operating range of the bender
actuator. As discussed above, the system resonances may be varied
through, for example, the selection of both the combined mechanical
and fluidic spring stiffness and the combined effective moving
masses of the system. In FIG. 1 for example, the system resonant
frequency may be varied by changing the stiffness and/or mass of
diaphragm 6, changing the mass and/or stiffness of stand-off 12,
the mass of bender actuator 14, or changing the properties and/or
pressure of the fluid within cavity 2.
[0197] FIG. 3 provides an embodiment of the present invention
including the addition of a reaction mass to the bender actuator,
which may improve power transfer. In FIG. 3 a cylindrical
fluid-filled cavity 22 is bounded by enclosure 20 and circular
diaphragm 24. Diaphragm 24 is held around its perimeter between
O-ring 26 and O-ring 28 being clamped into enclosure 20 by threaded
clamp ring 30. One end of standoff 32 is rigidly connected to the
center of diaphragm 24 with the other end of standoff 32 being
rigidly connected to the center of bender actuator 34. An annular
reaction mass 36 is rigidly connected to the perimeter of bender
disk 34.
[0198] The role of the reaction mass as may be used in some
embodiments will now be explained. If the effective moving mass at
the bender actuator's perimeter is relatively small, then much of
the bender's force output may be shunted into oscillating the
bender's perimeter between the displacement extremes 16 and 17
shown in FIG. 2, possibly resulting in reduced power delivery
through standoff 32 into the fluid load. Reaction mass 36 provides
a mass for bender 34 to push against and thus may cause more force
to be delivered to diaphragm 24 (as compared to without the
reaction mass 36) and thus more power being delivered to the fluid
load. The optimal mass to be added for achieving a given design
performance goal may be determined by, for example, modeling or by
experiment. Changing the mass of annular reaction mass 36 will
typically also change the effective moving mass M of the system,
which in turn will change the frequency
f.sub.o=(1/2.pi.)(K/M).sup.1/2 of the system resonance.
[0199] Some embodiments of the present invention may be improved by
taking power factors into consideration. A typical power factor is
expressed in the form of cos .theta., where .theta. is the time
phase angle between a time varying force F(t)=F cos(.omega.t) and
the resulting velocity V of the driven component so that the
delivered power is FV cos .theta.. For maximum power transfer to
the load, the ideal power factor is unity, implying that .theta. is
zero. For a given power-delivery design target, if the power factor
cos .theta. drops below 1, then the product FV must increase
proportionately to maintain the power-delivery target. Increasing F
to maintain power transfer reduces efficiency and increasing V to
maintain power transfer increase the stress, vibration, and
resulting noise of the device. For the present invention, the
bender's force is being delivered through a path that includes the
bender's own internal spring. As such, the time phase .theta.
between F and V for a given design will not necessarily be equal to
zero at resonance. In order to optimize energy efficiency and
minimize noise and vibration it is desirable to tune the system in
order to keep the phase angle .theta. as close to zero as
possible.
[0200] The performance of some embodiments of the present invention
can be altered by the magnitude of the effective moving mass M as
well as how M is distributed between the various moving components.
Referring to FIG. 3, the total effective moving mass M can be
approximately defined as two separate moving masses defined as a
fluid diaphragm mass M.sub.D and a reaction mass M.sub.R. M.sub.D
is equal to the sum of the effective dynamic mass of diaphragm 24,
the mass of standoff 32, and a central portion of bender 34.
M.sub.R is equal to the sum of the annular reaction mass 36 and a
portion of bender 34 with said portion extending radially from
reaction mass 36 towards the center of bender 34. M.sub.D and
M.sub.R are connected by the spring stiffness of bender 34 and the
time phase between their respective motions will depend on the
specific design, component values, and operating conditions. For
another embodiment of the present invention, the ratio of
M.sub.R/M.sub.D may be greater than 1 in order to increase
mechanical power transfer to the fluid load. For a constant peak
drive force, when M.sub.R is increased from a value of zero, while
holding M.sub.D constant, transduction efficiency generally
increases and power transfer can be found to reach a maximum at
some value of M.sub.R/M.sub.D. Performance may be enhanced by
keeping the magnitude of M=(M.sub.R+M.sub.D) to a minimum for a
given application, so as to minimize the amount of force that is
shunted from the load in order to accelerate mass M. In this way,
minimizing the magnitude of M may maximize the systems overall
energy efficiency.
[0201] While all of the masses and spring constants described above
may be changed in order to optimize the power factor, additional
components may be added to further change (improve) the mechanical
power factor. In FIG. 4 for example, stand-off 26 of FIG. 3 has
been replaced with an elliptical spring 38. Spring 38 provides a
resilient connection between bender actuator 40 and diaphragm 42.
Changes in the spring stiffness, mass, and damping constant of
spring 38 can be used to tune the phase angle .theta. and so
compensate for the non-ideal power-factor characteristics of bender
actuator 40. In the embodiment of FIG. 4, the characteristics
chosen for spring 38 may depend on the performance specifications
of a given application, but will be generally chosen to minimize
the time phase angle .theta.. In these discussions, the oscillation
of the pump body in response to the diaphragm reaction forces must
also be considered.
[0202] FIG. 5 shows another tuning spring arrangement having a
bender actuator 44, a cylindrical reaction mass 46 attached to the
center of bender 44, an annular standoff 48 having its lower
surface attached to the perimeter of bender 44, a disk tuning
spring 50 having its perimeter attached to the upper surface of
annular standoff 48, and a cylindrical standoff 52 having its lower
surface attached to the center of tuning spring 50 and its upper
surface attached to the center of fluidic diaphragm 54. In the
embodiment of FIG. 5, the perimeter of bender 44 serves as the PTO
point. Oscillating forces from bender 44 are transmitted in turn
from the perimeter of bender 44, through standoff 48, through disk
tuning spring 50, through stand-off 52, and finally to fluidic
diaphragm 42. Alternatively in FIG. 5, reaction mass 46 could be
connected to the opposite face of bender disk 34. In the embodiment
of FIG. 5, the characteristics of spring 50 may depend on the
performance specifications of a given application, and may be
chosen to optimize the time phase angle .theta..
[0203] The tuning springs depicted in FIGS. 4 and 5, and in other
exemplary embodiments, may be replaced with different style
springs, such as, for example, leaf springs and coil springs, and
could provide linear or nonlinear stiffness characteristics.
[0204] Depending on the specific application and design of the
present invention, the bending amplitude of the bender actuator may
be less than, equal to, or greater than the displacement of the
diaphragm and/or piston. For example, varying the ratio of
M.sub.R/M.sub.D may result in the bending amplitude of the bender
actuator being less than, equal to, or greater than the
displacement of the diaphragm and/or piston. Further, the degree of
linearity or nonlinearity of the mechanical and fluidic springs in
the system may result in the bending amplitude of the bender
actuator being less than, equal to, or greater than the
displacement of the diaphragm and/or piston. The ratio of
displacements between the diaphragm/piston and bender actuator is
not necessarily a constant during operation. For some applications
such as pumps or compressors, the ratio of
bender-to-diaphragm/piston displacement may vary during operation
from less than one, to unity, or to greater than 1.
[0205] The mechanical resonance frequency of a bender disk, with
respect to the system resonance frequency, may also be of benefit
in improving system performance and maximizing the mechanical
power-factor. However, in some embodiments, care may be taken in
the system design to prevent the system resonance frequency from
coinciding with the bender disk resonance frequency. In many
embodiments, the bender resonance frequency chosen may be above the
expected operating range of the system. For applications such as
pumps and compressors, where the system resonance frequency can
change, a resonance controller may be used to keep the electrical
drive frequency locked to the changing system resonance frequency.
In some embodiments of the invention, the bender disk's mechanical
resonance frequency may not be tuned close to the system resonance
frequency, so that the two resonant frequencies are not likely to
overlap during operation, thus reducing possible problems for the
resonance controller due to resonance repulsion phenomena.
Axial Stability
[0206] For the reaction-drive embodiments of FIGS. 1, 3, 4, and 5,
the desired displacements that perform useful work are in the axial
direction. As such, many embodiments will have the center of
gravity of the moving components, such as the bender disk, reaction
mass, or springs, be close to the axis of motion. Axial centering
may help to minimize off-axis moments of inertia that could lead to
transverse oscillations of the moving masses that may create
additional stresses on the diaphragm and unwanted system
vibrations. Also, the embodiments of FIGS. 1, 3, 4, and 5 may have
non-axial resonance modes which could be excited by an unbalanced
moving mass thereby intensifying the diaphragm's mechanical
stresses. In many embodiments, the designs will endeavor to avoid
the coincidence of non-axial mode frequencies with the drive
frequency.
[0207] Transverse modes may be further discouraged by adding
stabilizing components that may allow axial motion while rejecting
transverse motion. FIG. 6 provides an embodiment of the present
invention for rejecting or substantially rejecting transverse
motion, where a cylindrical fluid-filled cavity 56 is bounded by
enclosure 58 and circular fluidic diaphragm 60. Diaphragm 60 is
held around its perimeter between O-ring 62 and O-ring 64 being
clamped into enclosure 58 by threaded clamp ring 66. Fluidic
diaphragm 60 is attached to cylindrical standoff 68 with the other
end of standoff 68 being attached to bender actuator 70. Attached
to the perimeter of bender actuator 70 is annular reaction mass 72.
A stabilizing disk 76 is rigidly connected to enclosure 58 by being
clamped between clamp ring 66 and second clamp ring 78 and
stabilizing disk 76 is rigidly connected to bender 70 by
cylindrical stabilizing standoff 74. Stabilizing disk spring 76 is
designed so as to be axially compliant but comparatively stiff in a
direction transverse to the desired axial motion. Stabilizing disk
76 can be constructed of any number of materials including metals,
plastics, or elastomers as long as excessive motional
damping/substantial motional damping is avoided. Stabilizing disk
spring 76 of FIG. 6 need not necessarily be a disk, but could
instead, for example, comprise any number of leaf spring shapes or
profiles. The PTO point for bender 70 of this embodiment is
presented at the center of bender 70.
[0208] In FIG. 6, alignment disk 76 is displaced from the plane of
diaphragm 60 by a distance D. Increasing D may result in increased
transverse rejection. The exact value of D chosen for a given
design may represent a compromise between the desired level of
transverse rejection and the physical size of the system. Alignment
disk 76 may also be constructed with a radially serpentine profile
to increase its axial compliance. In summary, axial stability may
be enhanced by providing an axially-compliant transversely-stiff
component that is attached to the moving components at a point
removed some distance D from the fluidic diaphragm's plane. As
such, any number of stabilizing components may be used, such as
sliding bushings, thrust bearings, or springs, etc.
[0209] FIG. 6a provides an embodiment of the present invention for
rejecting or substantially rejecting transverse motion, where a
cylindrical fluid-filled cavity 300 is bounded by enclosure 302 and
circular fluidic diaphragm 304. Diaphragm 304 is held around its
perimeter between O-ring 306 and O-ring 308 being clamped into
enclosure 302 by threaded clamp ring 310. Fluidic diaphragm 304 is
attached to cylindrical standoff 312 with the other end of standoff
312 being attached to bender actuator 314. Attached to the
perimeter of bender actuator 314 is annular reaction mass 316. A
stabilizing disk 318 is rigidly connected to enclosure 302 by being
clamped between clamp ring 310 and second clamp ring 320 and
stabilizing disk 318 is rigidly connected to the perimeter 322 of
bender 314. Stabilizing disk spring 318 is designed so as to
present a low spring stiffness to axial motion but a high spring
stiffness in a direction transverse to the desired axial motion.
Stabilizing disk 318 can be constructed of any number of materials
including metals, plastics, or elastomers as long as excessive
spring stiffness and excessive motional damping/substantial
motional damping is avoided. Stabilizing disk spring 318 of FIG. 6a
need not necessarily be a disk, but could instead, for example,
comprise any number of leaf spring shapes or profiles.
[0210] Referring to FIG. 6a, many of the advantages of the present
invention result from bender 314 being connected to fluid diaphragm
304, or a similar fluid piston, while avoiding rigid secondary
connections between enclosure 302 and other parts of bender 314. To
prevent such secondary connections from being rigid any such
secondary connection should be resilient, which is to say the
secondary connection should have a small spring constant value k so
as to not to overly constrain the advantageous dynamics of the
present invention. For example, if stabilizing spring 318 of FIG.
6a were made extremely stiff so as to effectively ground the
perimeter 322 of bender 314 to enclosure 302, then the displacement
of diaphragm 304 could never exceed the bending displacement of
bender 312. However, it is understood that the spring stiffness k
of any secondary connection can have a range of stiffness values
and that there may be a corresponding range of performance values
such as resulting diaphragm or piston stroke, power delivered to
the fluid load, mechanical transduction efficiency, etc.
[0211] In terms of compliance, the stiffness k of spring 318 could
ideally be varied over a range whereby the constraint imposed on
bender 314 would correspondingly vary over a compliance range from
infinity (no constraint) to zero (completely rigid). Performance
would increase with the compliance C=1/k of spring 318. For
example, if the peak force of bender 314 were held constant while
the compliance C of spring 318 was progressively reduced from an
infinite value to a value of zero, then the displacement of
diaphragm (or a piston) 304 would change from a maximum value
(determined by all of the component values and fluid
characteristics) to a value equal to the bender's maximum
displacement. So for constant peak force, if the compliance C of
spring 318 was reduced such that the displacement of diaphragm 304
were reduced 10%, then performance would be reduced by roughly 10%.
If the compliance C of spring 318 was reduced such that the
displacement of diaphragm 304 was reduced 20%, then performance
would be reduced by roughly 20%. If the compliance C of spring 318
was reduced such that the displacement of diaphragm 304 was reduced
30%, then performance would be reduced by roughly 30%. If the
compliance C of spring 318 was reduced such that the displacement
of diaphragm 304 was reduced 40%, then performance would be reduced
by roughly 40%. If the compliance C of spring 318 was reduced such
that the displacement of diaphragm 304 was reduced 50%, then
performance would be reduced by roughly 50% and so on until the
compliance C of reaches a value of zero and the diaphragm or piston
displacement becomes limited to that of bender 314. The preceding
assumes of course that the system is being driven at or near its
system resonance f.sub.o, which may shift with changing values of
C. Accordingly, a secondary bender connection having a non-zero
compliance is considered to be within the scope of the present
invention.
Reaction-Drive Pumps
[0212] The reaction-drive methods described above provide a compact
diaphragm actuator system for the diaphragm pumps and compressors
of the present invention. The low profile topology of a
reaction-drive system enables high-performance miniaturization of
diaphragm type pumps down into the MESO and MEMS size range.
[0213] FIG. 7 illustrates a reaction-drive pump embodiment of the
present invention which shows a top view and side view of a pump
79, where the top is shown with plenum cover plate 88 removed. In
FIG. 7 a pump body 80 is provided with O-ring seal 82 that creates
a pressure seal between pump body 80 and actuator cover plate 86
and where pump body 80 is provided with O-ring seal 84 that creates
a pressure seal between pump body 80 and plenum cover plate 88.
Pump 79 is further provided with a fluidic diaphragm 90 being held
around its perimeter between O-ring 92 and O-ring 94 being clamped
into pump body 80 by threaded clamp ring 96. Fluidic diaphragm 90
is typically constructed of metal but could also be constructed of
other materials. Standoff 98 is rigidly connected to the center of
diaphragm 90 with the other end of standoff 98 being rigidly
connected to the center of bender actuator 100. Annular reaction
mass 102 is connected to the perimeter of bender actuator 100.
Electrical wires 104 connect bender actuator 100 to pressure-tight
electrical feedthroughs 106 which all serve to connect the bender
actuator to an external voltage waveform generator. A compression
chamber 108 is bounded by fluidic diaphragm 90 and pump body
80.
[0214] Pump body 80 of FIG. 7 is also provided with annular
discharge plenum 110 and cylindrical inlet plenum 112, where
discharge plenum 110 and cylindrical inlet plenum 112 are
co-axially located in pump body 80. Discharge plenum 110 is
connected to compression chamber 108 by six discharge ports 114 as
shown in the top view of FIG. 7 but not shown in the plane of the
side view. Inlet plenum 112 is connected to compression chamber 108
by six inlet ports 116. Seated on the floor 118 of discharge plenum
110 and covering discharge ports 114 is discharge reed valve 120,
the profile of which is shown in the top view of FIG. 7. Seated on
the floor 122 of inlet plenum 112 and covering inlet ports 116 is
inlet reed valve 124, the profile of which is shown with the dotted
line in the top view of FIG. 7. Discharge reed valve 120 is pressed
around its perimeter against floor 118 of discharge plenum 110 by
annular spacer 126 which is in turn clamped by plenum cover plate
88. Inlet reed valve 124 is pressed around its perimeter against
upper surface 128 of compression cavity 108 by O-ring 92. The inlet
and discharge reed valves of the present embodiment are typically
constructed from flapper valve steel and are from 0.001-0.004 mils
thick for small compressor running in the 200-300 Hz frequency
range. A gasket 130 creates a pressure seal between discharge
plenum 110 and inlet plenum 112. Within plenum cover plate 88 is an
inlet passage 132 that directs flow from the outside of pump 79 to
inlet plenum 112 and an discharge passage 134 that directs flow out
of discharge plenum 110 to the exterior of pump 79.
[0215] In operation, an alternating voltage waveform of frequency f
is applied to bender actuator 100 causing it to oscillate at
frequency f between bending deflections such as, by way of example,
those shown in FIG. 2. As bender actuator 100 mechanically
oscillates at frequency f oscillating forces may be transmitted to
fluidic diaphragm 90 through standoff 98 causing diaphragm 90 to
also oscillate at frequency f thereby causing the pressure within
compression chamber 108 to oscillate at frequency f. In the
embodiment of FIG. 7, the power-take-off (PTO) point from bender
actuator 100 is at the center of bender actuator 100. If the
electrical drive frequency f is equal to or close to the system
resonance frequency f.sub.o then the displacements of fluidic
diaphragm 90 should increase proportionately or substantially
proportionately to the system's resonance quality factor Q at
frequency f. In such an embodiment, the system resonance frequency
f.sub.o at a given operating condition may be determined by the
stiffness of the combined mechanical and fluidic springs, the
effective moving mass, and the damping related to pumping work
including the valve losses, etc.
[0216] The inlet stroke occurs when diaphragm 90 is moving downward
away from the upper surface 128 of compression chamber 108 and the
discharge stroke occurs when diaphragm 90 is moving up towards the
upper surface 128 of compression chamber 108. During the inlet
stroke, the fluid pressure within compression cavity 108 drops
below the fluid pressure within inlet plenum 112 and the resulting
pressure difference will open inlet reed valve 124 thus allowing
fluid to flow from inlet plenum 112 through inlet ports 116 and
into compression cavity 108. When diaphragm 90 reaches the bottom
of its stroke it reverses directions marking the beginning of the
compression stroke and the fluid pressure within compression
chamber begins to increase. When the fluid pressure within
compression cavity 108 rises above the fluid pressure within inlet
plenum 112 the resulting pressure difference will close inlet reed
valve 124 thus sealing inlet ports 116 and halting the fluid flow
from inlet plenum 112 into compression cavity 108. During the
compression stroke, the fluid pressure within compression cavity
108 rises above the fluid pressure within discharge plenum 110 and
the resulting pressure difference will open discharge reed valve
120 thus allowing fluid to flow from compression cavity 108 through
outlet ports 114 and into discharge plenum 110. When diaphragm 90
reaches the top of its stroke it reverses directions marking the
beginning of the inlet stroke and the fluid pressure within
compression chamber begins to decrease. When the fluid pressure
within compression cavity 108 falls below the fluid pressure within
discharge plenum 110, the resulting pressure difference will close
discharge reed valve 120 thus halting or effectively halting the
fluid flow from compression cavity 108 into discharge plenum 110.
In this way, a net fluid flow through pump 79 is created where
fluid is drawn in through inlet passage 132 and discharged through
discharge passage 134. Also assisting in the closing of the inlet
and discharge valves is the spring stiffness of the valves, which
will always tend to restore the valves to the closed position.
[0217] Diaphragm 90 of pump 79 in the embodiment depicted in FIG. 7
does not have a fixed displacement. Within the displacement limits
of diaphragm 90, the displacement amplitude of diaphragm 90 may be
varied by changing the amplitude of the driving voltage waveform,
by changing the drive frequency with respect to the system
resonance frequency, or by changing both voltage amplitude and
frequency. As such, diaphragm 90 is free to move between a
plurality of first positions and a plurality of second positions,
wherein the first positions are proximal to surface 128 of
compression chamber 108 at the top of a respective compression
stroke and the second positions are distal to the surface 128 of
compression chamber 108 at the end of a respective suction stroke.
The diaphragm is operably movable to a plurality of the first
positions on successive compression strokes and a plurality of
second positions on successive suction strokes in response to
varying drive voltage or drive frequency. This plurality of
diaphragm displacement amplitudes provides variable capacity
operation both for pump 79 and for all of the other pump
embodiments of the present invention, whereby varying the
diaphragm's displacement will cause the pump's capacity to vary.
This variable capacity feature can be used with either liquids or
gases.
[0218] Pump 79 of FIG. 7 is approximately 2.25 inches in diameter
as measured across the pump body. Diaphragms used are typically
made of flapper valve steel with thicknesses of roughly 0.002-0.005
inches. For air, typical operating frequencies vary from 200-400 Hz
based on the compression ratio, flow rate, and specific design of
the system.
[0219] It is to be understood that in many other embodiments of the
invention, the relative diameters of the bender actuator and the
fluidic diaphragm will be different than those recited herein by
example. The diameter of the bender could be either larger than or
smaller than the diameter of the fluidic diaphragm. Both the force
needed to drive the fluidic diaphragm as well as the pump's flow
capacity increases with the diameter of the fluidic diaphragm. The
diameter of the bender actuator needed to provide the desired force
will vary with the type of bender actuator.
Pressurized Operation and Pressure Equalization
[0220] O-rings 82 and 84 of FIG. 7 provide pressure sealing for
pump body 80 and allow for operation with high-pressure fluids. For
example, the pump of many embodiments of the present invention may
be used as a compressor in a refrigeration or heat-pump loop and
lends itself to spot cooling or heating applications where small
compressors are needed. FIG. 8 shows a vapor-compression heat
transfer cycle, having a refrigerant compressor 140, a condenser
142, a pressure drop capillary tube 144, an evaporator 146, and a
cooled region 148. In operation compressor 140 provides flow and
pressure lift for the refrigerant which flows clockwise around the
loop where the gaseous refrigerant condenses to liquid in condenser
142, experiences a pressure drop in capillary tube 144, absorbs
heat from cooled region 148 and boils within evaporator 146, and
finally returns in a gas state to compressor 140.
[0221] For applications of pump 79 in FIG. 7 requiring a pressure
lift of the fluid, the diaphragm 90 may be prevented from
distorting in response to the elevated average pressure within
compression chamber 108. Higher average pressures within
compression chamber 108 may cause diaphragm 90 to bulge out away
from the inner surface 128 of compression chamber 108. For a given
peak-to-peak diaphragm displacement, this diaphragm distortion may
increase the pump's clearance volume and as well as increase the
bending stresses of the diaphragm 90.
[0222] Pressure-induced diaphragm distortion may be reduced by
increasing the stiffness of diaphragm 90. Another method of
controlling pressure-induced diaphragm distortion may be to
equalize=the pressure on both sides of the fluidic diaphragm 90. As
shown in FIG. 7, a pressure equalization hole 136 in diaphragm 90
may provide pressure equalization for the pumps of the present
invention. If the average fluid pressure within compression chamber
108 rises above the fluid pressure within actuator chamber 138,
then the resulting pressure difference may cause fluid to flow from
compression chamber 108 into actuator chamber 138 until the
pressures are equalized.
[0223] The diameter of pressure equalization hole 136 may be chosen
to provide a pressure equalization time-constant that is many
pumping cycles in duration. If the flow rate time-constant is to
short (hole to large), then the pump's flow capacity and efficiency
might be reduced since energy might be wasted pumping fluid in and
out hole 136 each pumping cycle. If the flow rate time-constant is
relatively long (e.g., the hole is to small), then pressure
equalization could be to slow to prevent diaphragm distortion.
Sizing of hole 136 may be determined from orifice flow calculations
based on a given pressure differential across the hole and the
volume of actuator chamber 138. As an alternative to diaphragm hole
136, drillings through the pump body 80 could be used that connect
the compression chamber 108 to actuator chamber 138.
Clearance Volume
[0224] In most embodiments of the present invention, the
compression ratio that may be achieved is based on the pump's
clearance volume, since the compression
ratio=(V.sub.s+V.sub.c)/V.sub.c where V.sub.s is swept volume and
V.sub.c is clearance volume. The clearance volume is the volume of
the compression chamber when the diaphragm is at the top of its
stroke.
[0225] When diaphragm 90 of pump 79, in FIG. 7, is at the top of
its stroke a substantial clearance volume will remain around the
perimeter of compression chamber 108. For a design like that of
pump 79, the clearance volume at the maximum stroke could be, for
example, as large as 1/3 of the swept volume. For applications
where no pressure lift is required the design of pump 79 may
provide the needed performance.
[0226] FIG. 9 shows an embodiment of the present invention that
reduces the clearance volume. In FIG. 9, a side view and a top view
are provided, where the top view is seen with the plenum cap
removed. In FIG. 9 a pump 162 is provided, where O-ring 92 of FIG.
7 has been replaced with tapered ring 150. To avoid covering the
discharge ports, tapered ring 150 has ports that coincide with the
discharge ports in compressor body 160 but are not shown in the
cross-sectional view of FIG. 9, since the cross-sectional plane
does not cut through the ports. Pump 162 also replaces inlet reed
valve 124 of FIG. 7 with inlet reed valve 154 shown in the top view
of FIG. 9 with the dotted line. Inlet reed 154 is centrally located
on the upper surface 158 of compression chamber 152 so as not to
interfere with tapered O-ring 150. In operation, when diaphragm 156
is displaced toward the upper surface 158 of compression chamber
152, the bending profile of diaphragm 156 around its perimeter is
intended to closely match the radial contour of tapered ring 150,
thereby reducing the clearance volume of compression chamber 152.
Alternatively, the contour of tapered ring 150 could be included in
pump body 160 as part of its integral structure. Many methods and
configurations for reducing the clearance volume of diaphragm
compressors may be used to practice such embodiments of the
invention.
[0227] FIG. 10 provides an embodiment of the present invention for
further reducing the clearance volume of an oscillating pump, where
standoff 170 of pump 168 has an upper section 164 having a diameter
D and being rigidly attached to diaphragm 166. The area of
diaphragm 166 that is attached to section 164 of standoff 170 may
be constrained to move in a planar manner like a piston face, while
the outer section of diaphragm 166, having a diameter greater than
D and less than the clamped diameter, will be free to flex like a
surrounding membrane. This piston-diaphragm configuration in
combination with the tapered compression chamber will result in
less clearance volume than pump 162 FIG. 9. The piston-like design
of pump 168 may increase the stresses on diaphragm 166 for a given
displacement, and thus may drive the choice of diaphragm material
and thickness. However, the increased performance may allow the
displacement to be reduced for a given operating condition, thereby
tending to offset the higher stresses on the diaphragm.
[0228] The compression chamber heights and contours shown in FIGS.
9 & 10 are somewhat exaggerated for clarity. When shaping the
compression chamber to minimize clearance volume, the specific
contour used will be determined by the shape of the
diaphragm-piston at its maximum stroke, which in turn will be a
function of the specific design chosen.
[0229] For some embodiments of the present invention, the
particular design may represent a compromise between low clearance
volume and the way in which the spring properties of fluid within
the compression cavity affect the system dynamics. A low clearance
volume can result in less fluid remaining at the end of a
compression stroke and thus less fluid spring stiffness and
associated restoring force. If a very low clearance volume is
desired then mechanical springs can be added to compensate for the
lost fluidic spring stiffness. Such mechanical springs can take the
form of alignment disk 76 in FIG. 6, leaf springs, or can simply
involve using a stiffer fluidic diaphragm.
[0230] Many other embodiments for reducing clearance volume will
occur to those that are skilled in the art for reducing clearance
volume. Other variations in how a piston can interface with the
compression chamber to reduce clearance volume is seen in the prior
art patents U.S. Pat. No. 3,572,908, U.S. Pat. No. 6,514,047, G.B.
Pat. 428,632, G.B. Pat. 700,368, and U.S. Pat. No. 4,874,299, the
contents of which are incorporated herein by reference in their
entirety.
Valves
[0231] The relatively high operating frequencies of the present
invention mean that passive valve designs often will take into
consideration certain fluidic and mechanical dynamics issues that
become increasingly important at higher frequencies. These
frequency-related effects include, for example, the inertia and
spring stiffness of the moving valves and related opening and
closing times, inertial timing effects of the fluid as it is
accelerated through the valve and valve port flow path, and the
effect that the size and cross-sectional profile of the valve ports
has on fluid flow timing. These parameters may be used to enhance
the flow and pressure performance of a given pump design and can be
successfully modeled with a number of numerical lumped-element
models. In pumps of some of the embodiments, reed valves without
valve stops may be used in order to provide low profile valves.
When valve stops are absent the valves must be tuned by choosing
the proper valve stiffness and valve mass in order to achieve good
valve timing for a particular pump operating frequency, flow, and
compression ratio.
[0232] Some embodiments of the present invention can operate
without moving mechanical valves, such as reed valves, by proper
tuning of the valve ports. Valve port tuning may take the form of
various valve port types that are well known in the art such as
diffuser valves, nozzle valves, and Tesla valves, to name a few.
These valve ports typically present a changing cross-sectional area
to the fluid flow passing through the port and are designed to
present a low flow-impedance in one direction and a high
flow-impedance in the opposite direction. This difference in
directional flow impedances creates a rectifying effect that
converts an oscillating flow into a net flow in one direction.
Although tuned ports alone cannot provide the flow and pressure
performance of mechanical valves, such as reed valves, they provide
simplicity and reliability and can be scaled to small sizes and
high frequencies.
[0233] Pumps of some embodiments of the present invention may also
use actuated valves that may be actuated by bender actuators,
electromagnetic actuators, electrostatic actuators, or other
actuators that can provide the displacement and frequency response
required by a given application. Pumps according to some
embodiments may also employ valve stops that limit the opening
height of valves in order to optimize valve performance as in well
known in the art of pump valves.
[0234] FIG. 11 illustrates another pump embodiment of the present
invention where the inlet reed valves are located on the moving
diaphragm-piston assembly. In FIG. 11 pump 172 comprises a pump
body 174, a bender actuator 176, a standoff 178 having its lower
end rigidly connected to bender actuator 176 and its upper end
rigidly connected to fluidic diaphragm 180. Standoff 178 is
provided with six inlet ports 182 on a circle, where only two of
the six inlet ports 182 are shown in the plane of the
cross-sectional view of pump 172. An inlet reed valve 184 is
rigidly attached to the center of diaphragm 180 so that the petals
of inlet reed valve 184 cover inlet ports 182. Pump body 174 is
provided with six outlet ports 186 on a circle, where only two of
the six outlet ports 186 are shown in the plane of the cross
sectional view of pump 172. Outlet reed valve 188 is rigidly
connected around its perimeter to surface 190 of pump body 174 so
that the petals of outlet reed 188 cover outlet ports 186.
[0235] In operation, a voltage waveform of frequency f is applied
to bender actuator 176 which excites the system resonance of pump
172, as described previously, and fluidic diaphragm 180 oscillates
in response between two displacement extremes, thereby causing the
fluid pressure within compression cavity 196 to oscillate at
frequency f. In response to the oscillating fluid pressure within
compression cavity 196, inlet valve 184 and outlet valve 188 open
and close in sequence once per cycle, thereby drawing a low
pressure fluid in through pump body inlet 194, through actuator
chamber 200, through inlet ports 182 and into compression chamber
196, and then discharging a high pressure fluid through outlet
ports 186, through outlet plenum 198, and out of pump 172 through
pump body outlet 192. Locating the inlet ports and inlet reed
valves on standoff 178 provides design flexibility and enables
further downsizing of the pump. Another advantage is that the
motion of the piston will provide a natural actuation of the inlet
valves, where the inertia of the valve and the motion of the piston
will tend to open and close the valve in proper phase with the
pressure cycle.
[0236] A simple redesign of the reed valves, for pump 172 of FIG.
11, would allow the outlet valves to be located on standoff 178
thus cover the backside of ports 182 and allow the inlet valves to
be located on surface 190 of pump body 174. In this case, the
outlet valves, rather than the inlet valves, would have the benefit
of actuation.
Reduction of Pump Vibrations
[0237] In some embodiments of the present invention, the higher the
fluid compression, the greater the potential vibration amplitudes
of the pump. FIG. 12 illustrates an embodiment of the present
invention that may reduce the pump's vibration. Here, two opposing
fluidic diaphragms are present. In FIG. 12, a pump 202 is provided
comprising a pump body 204, a first bender actuator 206, a first
standoff 208 having its lower end rigidly connected to first bender
actuator 206 and its upper end rigidly connected to first fluidic
diaphragm 210. First standoff 208 is provided with six outlet ports
212 on a circle, where only two of the six outlet ports 212 are
shown in the plane of the cross-sectional view of pump 202. An
outlet reed valve 214 is mounted flush to lower surface 216 of
first standoff 208, so that the petals of outlet reed valve 214
cover outlet ports 212. Inner ring 218 of outlet reed valve 214 is
rigidly attached to lower surface 216 of first standoff 208 leaving
the petals of outlet reed valve 214 free to open and close in a
cantilever fashion.
[0238] Pump 202 is further provided with a second bender actuator
220, a second standoff 222 having its upper end rigidly connected
to second bender actuator 220 and its upper end rigidly connected
to second fluidic diaphragm 224. Second standoff 222 is provided
with six inlet ports 226 on a circle, where only two of the six
outlet ports 226 are shown in the plane of the cross-sectional view
of pump 202. An inlet reed valve 228 is mounted flush to lower
surface 230 of second fluidic diaphragm 224, so that the petals of
inlet reed valve 228 cover inlet ports 226. The central area 232 of
inlet reed valve 228 is rigidly attached to lower surface 230 of
second fluidic diaphragm 224 so as to leave the petals of inlet
reed valve 228 free to open and close in a cantilever fashion. Pump
202 is also provided with a pump enclosure comprising a cylindrical
housing 236, an upper enclosure cap 238 and a lower enclosure cap
240. Cylindrical housing 236 has housing inlet 250 and housing
outlet 248. Cylindrical housing 236 is connected to pump body 204
by a resilient annular ring 242 which provides a pressure seal
between discharge plenum 244 and inlet plenum 246.
[0239] In operation, a voltage waveform of frequency f is applied
to both first and second bender actuators 206 and 220, thus causing
both first and second fluidic diaphragms 210 and 224 to oscillate
in response between their respective displacement extremes. The
voltage waveform of frequency f is applied to first and second
benders actuators 206 and 220 with the same time phase, thereby
assuring that each fluidic diaphragm will traverse their
compression and inlet strokes in unison and thereby causing the
fluid pressure within compression cavity 234 to oscillate at
frequency f. In response to the oscillating fluid pressure within
compression cavity 234, outlet valve 214 and inlet valve 228 will
open and close in sequence once per cycle, thereby drawing a low
pressure fluid in through housing inlet 250, through inlet plenum
246, through inlet ports 226 and into compression chamber 234, and
then discharging a high pressure fluid through outlet ports 212,
through outlet plenum 244, and out through housing outlet 248.
[0240] Pump 202 of FIG. 12 may have the following aspects Locating
outlet valve 214 and inlet valve 228 on respective first and second
standoffs 208 and 222 provides design flexibility and may enable
further downsizing of the pump. Another aspect of this embodiment
is that the motion of the first and second standoffs 208 and 222
may provide a natural actuation of discharge valve 214 and inlet
valve 228, where the inertia of the valves and the motion of their
respective standoffs may tend to open and close the valves in
proper phase with the pressure cycle. A further advantage is
provided by resilient annular ring 242 which creates a level of
vibration isolation between pump body 204 and the pump housing. The
stiffness of annular ring 242 will be chosen by the designer to
minimize vibration transmission from pump body 204 to pump housing
242 as is well understood in the art of vibration control.
Alternatively, the valves of pump 202 in FIG. 12 could be mounted
in a stationary fashion within pump body 204 around the perimeter
of compression chamber 234.
[0241] Pump 202 of FIG. 12 can benefit from other aspects of other
embodiments disclosed herein, such as, by way of example, tuning
springs for improving mechanical power factors, stabilizing springs
to improve axial stability, etc.
Drive Circuits & Controls
[0242] The pump embodiments of the present invention rely on the
system's mechanical resonance to provide large fluidic diaphragm
displacements. Changing operating conditions may shift the system's
resonance frequency. For example, the pumps of the present
invention may be nonlinear mechanical oscillators in that their
system resonance frequency may change with drive amplitude. As
such, a resonance controller may be used when the application calls
for changes in drive voltage in order to change the pump's flow
capacity and pressure. One exemplary resonance controller is shown
in FIG. 13 where a pump 252 of the present invention is provided
with a function generator 254, a drive amplifier 256, a
microprocessor 258, and a low resistance resistor 260. In
operation, function generator 254 provides a voltage waveform of
frequency f to amplifier 256 which in turns delivers the amplified
voltage waveform to the bender actuator terminals of pump 252. For
a given voltage amplitude V.sub.o, microprocessor 258 measures the
time varying voltage V(t) across the terminals of pump 252, the
time varying current I(t) across resistor 260, and the time phase
angle .phi. between V(t) and I(t). Microprocessor 258 then
calculates the electrical power factor cos .phi. and then
calculates the delivered electrical power P=V(t)I(t)cos .phi.. The
delivered electrical power P reaches a maximum at the system
resonance frequency f.sub.o. Thus microprocessor 258 keeps the
drive frequency f close to the system resonance frequency f.sub.o
by continuously running a search routine that makes incremental
changes in frequency f and then determines if P has increased or
decreased. If P decreases for a given frequency change, then
microprocessor 258 makes a step change in frequency having an
arithmetic sign that is opposite to the previous frequency change
step. If P increases for a given frequency change, then
microprocessor 258 makes a step change in frequency having the same
arithmetic sign as the previous frequency change step.
[0243] Many other resonance control methods can be used. For
example, the parameter being maximized by the resonance controller
could be a signal provided by a displacement sensor proximal to the
bender actuator, a pressure sensor at the pump's outlet, or an
accelerometer attached to the pump body. Another approach would be
to use a phase locked loop PLL to maintain a target time phase
angle between drive voltage and current that corresponds to a
desired drive frequency being equal to or near the system resonance
frequency.
[0244] For pumps having two opposed fluidic diaphragms, such as
pump 202 of FIG. 12, force cancellation may be enhanced with
additional controls. The circuit shown in FIG. 14 provides one
embodiment of a force cancellation control as well as a resonance
controller like that of FIG. 13. In FIG. 14 a dual-diaphragm pump
262 of the present invention has a first bender actuator 280 and a
second bender actuator 282 and is further provided with a
controller circuit comprising a first amplifier 264, a second
amplifier 266, a microprocessor 268, a function generator 270, a
first current sensing resister 272, a second current sensing
resister 274, a first displacement sensor 276, a second
displacement sensor 278 and an accelerometer 284.
[0245] In operation, function generator 270 provides a voltage
waveform of frequency f to first and second amplifiers 264 and 266
where each amplifier delivers respective amplified voltage
waveforms to the first and second bender actuator 280 and 282 of
pump 262. For a given voltage amplitude V.sub.o, microprocessor 268
measures the time varying voltage V(t) across the terminals of
bender actuators 280 and 282, measures the time varying current
I(t) across resistors 272 and 274, and measures the time phase
angles .phi. between the respective V(t) and I(t) of bender
actuators 280 and 282. Microprocessor 268 then calculates the
electrical power factor cos .phi. and then calculates the delivered
electrical power P=V(t)I(t)cos .phi. for each bender actuator. The
delivered electrical power P reaches a maximum at the system
resonance frequency f.sub.o. Thus microprocessor 268 keeps the
drive frequency f of function generator 270 close to the system
resonance frequency f.sub.o by continuously running a search
routine that makes incremental changes in frequency f and then
determines if P has increased or decreased. If P decreases for a
given frequency change, then microprocessor 268 makes a step change
in frequency of having an arithmetic sign that is opposite to the
previous frequency change step. If P increases for a given
frequency change, then microprocessor 268 makes a step change in
frequency having the same arithmetic sign as the previous frequency
change step.
[0246] Running simultaneously with the resonance controller of FIG.
14, microprocessor 268 measures the displacement amplitudes of
bender actuators 280 and 282 by means of respective displacement
sensors 276 and 278 and makes adjustments to the gain of amplifiers
264 and 266 in order that the two diaphragms of pump 262 have equal
displacement amplitudes. Microprocessor 268 also monitors the
output of accelerometer 284 and makes further adjustments in the
relative gain of amplifiers 264 and 266 in order to minimize the
acceleration signal of accelerometer 284, thereby minimizing the
vibration of pump 262. Many other equivalent control schemes will
occur to those skilled in the art that can minimize pump vibration
by controlling the relative displacements of a two-diaphragm
compressor of the present invention. Other feedback sources for the
control circuit could include sensing the electrical
characteristics of the bender actuators as viewed at the bender's
terminals.
Synthetic Jets
[0247] Another application of the reaction-drive system according
to some embodiments of the invention is in the actuation of
synthetic jets. FIG. 15 shows a synthetic jet device 286 having a
reaction-drive actuator embodiment of the present invention, where
synthetic jet 286 is provided with a bender actuator 288 having a
reaction mass 290 being rigidly connected to the perimeter of
bender actuator 288, a fluidic diaphragm 292, a standoff 294 being
rigidly connected to the center of diaphragm 292 with the other end
of standoff 294 being rigidly connected to the center of bender
actuator 288, a fluid-filled cavity 296, and a port 298.
[0248] In operation the bender actuator 288 drives fluidic
diaphragm 292 at a frequency f so that energy is stored in the
system resonance and thus allows the displacement of fluidic
diaphragm 292 to exceed the bending displacement of bender actuator
288. The displacement oscillations of diaphragm 292 creates an
oscillating pressures within cavity 296 at frequency f thus causing
the fluid to oscillate back and forth in port 298 at frequency f.
As is known in the art of synthetic jets, the oscillation of the
fluid within port 298 creates a pulsating jet of flow that proceeds
away from synthetic jet 286 along the cylindrical axis of port 298.
One possible result of using a reaction-drive diaphragm actuator is
that more energy can be transferred to the fluid in the same sized
unit resulting in higher jet flows.
Fluid Applications
[0249] The reaction-drive actuator according to some embodiments of
the invention may be applied in a number of applications where
energy needs to be applied to fluids and especially for smaller
sized fluid applications. The reaction-drive actuator according to
some embodiments may be employed for applications such as atomizers
for any number of liquids including fuels; mixers for fuels, gases,
2-phase mixing such as with liquids and gases, and powders;
micro-reactors for chemical manufacturing, mixing in connection
with respiratory drug delivery. The pumps according to some
embodiments may be employed wherever pumps and compressors are
found in consumer, commercial, industrial, medical, and scientific
applications and are particularly advantageous where small size,
high performance, low noise, and low vibrations are required. Pumps
of the present invention can further be employed in applications
including the general compression of gases such as air,
hydrocarbons, process gases, high-purity gases, hazardous and
corrosive gases, as well as the compression of phase-change
refrigerants for refrigeration, air-conditioning and heat pumps,
and other specialty vapor-compression heat transfer
applications.
[0250] Some embodiments of the pump described herein may be used
with various consumer and industrial products. By way of example
only, some pumps may be used with miniaturized fuel cells for
portable electronic devices, such as portable computing devices,
PDAs and cell phones, self-contained thermal management systems
that can fit on a circuit card and provide cooling for
microprocessors and other semi-conductor electronics, and portable
personal medical devices for ambulatory patients, etc. Thus, the
present invention extends to apparatuses and systems, and methods
of using the pumps in such a manner.
[0251] The present invention includes methods of practicing the
invention, software to practice the invention, and apparatuses
configured to implement the present invention. Accordingly, the
present invention includes a program product and hardware and
firmware for implementing algorithms to practice the present
invention, as well as the systems and methods described herein, and
also for the control of the devices and implementation of the
methods described herein. Thus, by way of example, the present
invention includes a processor with logic to control a pump or a
component of the pump according to the present invention. It is
noted that the term "processor," as used herein, encompasses both
simple circuits and complex circuits, as well as computer
processors.
[0252] While the present invention enables miniaturization, the
scope of the present invention is in no way limited to embodiments
of any given size. Various embodiments and enhancements of the
present invention are disclosed herein and it will occur to those
skilled in the art to use many different combinations of these
embodiments and enhancements. All of the various combinations of
these embodiments will be determined by the requirements of a given
application and are considered within the scope of the present
invention. For example, the number of valves used, whether or not
added axial stability is required, the use of one or two
diaphragms, whether or not controls are needed, the types of
methods used for joining components, the type of bender actuator
used, the types of seals used, and the use of pumps in series or
parallel will all be determined by the performance and cost
requirements of a given application. Other examples of applications
within the scope of the present invention that will occur to those
skilled in the art would be to locate a single bender actuator
between two back-to-back fluidic diaphragms with each diaphragm
having their own compression chambers so as to drive the two
diaphragms with the single bender actuator in a push-pull
configuration. Further, pumps of the present invention can be
scaled up or down in size and can be used in closed cycle systems
as well as open systems as will be evident to those skilled in the
art.
[0253] The foregoing description of some of the embodiments of the
present invention have been presented for purposes of illustration
and description. It is not intended to be exhaustive or to limit
the invention to a precise form disclosed, and obviously many
modifications and variations are possible in light of the above
teaching. The embodiments were chosen and described in order to
best explain the principles of the invention and its practical
application to thereby enable others skilled in the art to best
utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated.
Although the above description contains many specifications, these
should not be construed as limitations on the scope of the
invention, but rather as an exemplification of alternative
embodiments thereof.
* * * * *