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.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

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

1) Field of Invention

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.

2) Description of Related Art

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

In another embodiment of the invention, there is a fluid energy transfer device comprising:

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

a bender actuator; wherein

the bender actuator is attached to the fluid diaphragm to form a bender-diaphragm 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 only due to the frequency of 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, and is exemplary greater than about an order of magnitude greater than the distance of peak-to-peak bending.

In another embodiment of the invention, there is a fluid energy transfer device comprising:

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

a bender actuator;

wherein the bender actuator is at least one of (i) connected directly to the fluid diaphragm and (ii) directly linked to the fluid diaphragm,

wherein the bender is effectively not connected and effectively not linked to any other component of the pump other than the diaphragm, and

wherein the bender is optionally connected to electrical leads adapted to conduct electrons to the bender.

In another embodiment of the present invention, there is a fluid energy transfer device comprising:

a fluid chamber having an inner wall shaped so as to form a chamber volume and having an opening;

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;

a fluid within the fluid chamber;

a fluid spring comprising the fluid within the fluidic chamber;

a mechanical spring comprising the diaphragm;

a bender actuator having an attachment point being attached to the fluidic diaphragm;

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.

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.

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.

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.

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.

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.

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.

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.

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.

In another embodiment of the present invention, there is a fluid transfer device as described above and/or below, further comprising:

an inlet port being connected in communication with the fluid chamber for flowing a fluid into the fluid chamber;

an outlet port being connected in communication with the fluid chamber for flowing a fluid out of the fluid chamber.

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;

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.

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.

In another embodiment of the present invention, there is a pump comprising:

a fluid chamber having an inner wall shaped so as to form a chamber volume and having an opening;

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;

an inlet port being connected in communication with the fluid chamber for flowing a fluid into the fluid chamber;

an outlet port being connected in communication with the fluid chamber for flowing a fluid out of the fluid chamber;

a fluid within the fluid chamber;

a fluid spring comprising the fluid within the fluid chamber;

a mechanical spring comprising the diaphragm;

a bender actuator having an attachment point being attached to the fluidic diaphragm;

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the control means further comprises:

a means for measuring selected operating conditions in the pump;

means for varying the drive frequency of the motor in response to the measured operating conditions in order to maximize the measured operating conditions.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the fluid is a gas.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the fluid is a liquid.

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.

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.

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.

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;

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.

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.

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.

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.

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.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the pump further comprises:

a plurality of inlet ports being connected in communication with the fluid chamber for flowing a fluid into the fluid chamber;

a plurality of outlet ports being connected in communication with the fluid chamber for flowing a fluid out of the fluid chamber.

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.

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.

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.

In another embodiment of the present invention, there is a pump comprising:

a fluid chamber having an inner wall shaped so as to form a chamber volume and having a first and second opening;

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;

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;

at least one inlet port being connected in communication with the fluid chamber for flowing a fluid into the fluid chamber;

at least one outlet port being connected in communication with the fluid chamber for flowing a fluid out of the fluid chamber;

a fluid within the fluid chamber;

a fluid spring comprising the fluid within the fluid chamber;

a first mechanical spring comprising the first diaphragm;

a second mechanical spring comprising the second diaphragm;

a first bender actuator having a first attachment point being attached to the first fluidic diaphragm;

a second bender actuator having a second attachment point being attached to the second fluidic diaphragm;

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.

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.

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.

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,

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.

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.

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.

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.

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.

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.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the control means further comprises:

a means for measuring selected operating conditions in the pump;

means for varying the drive frequency of the motor in response to the measured operating conditions in order to maximize the measured operating conditions.

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.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the fluid is a gas.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the fluid is a liquid.

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.

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.

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.

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;

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.

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.

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.

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.

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.

In another embodiment of the present invention, there is a pump as described above and/or below, wherein the pump further comprises:

a plurality of inlet ports being connected in communication with the fluid chamber for flowing a fluid into the fluid chamber;

a plurality of outlet ports being connected in communication with the fluid chamber for flowing a fluid out of the fluid chamber.

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.

In another embodiment of the present invention, there is a method of pumping a fluid comprising:

providing a pump for compressing a fluid, the pump comprising;

a fluid chamber having an inner wall shaped so as to form a chamber volume and having an opening;

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;

an inlet port being connected in communication with the fluid chamber for flowing a fluid into the fluid chamber;

an outlet port being connected in communication with the fluid chamber for flowing a fluid out of the fluid chamber;

a fluid within the fluid chamber;

a fluid spring comprising the fluid within the fluid chamber;

a mechanical spring comprising the diaphragm;

a bender actuator having an attachment point being attached to the fluidic diaphragm; the method further comprising:

introducing a fluid into the fluid chamber at a first pressure, wherein the fluid acts as a fluid spring under varying pressure conditions;

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;

operating the bender actuator at a drive frequency so as to store energy in the mass-spring mechanical resonance;

oscillating the diaphragm between the plurality of first positions and second positions;

compressing the fluid to a desired second pressure; and

evacuating the fluid from the compression chamber at the second pressure.

In another embodiment of the invention, there is a fluid energy transfer device comprising:

a fluid chamber for receiving a specific fluid having an inner wall shaped so as to form a chamber volume and having an opening;

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;

a bender actuator having an attachment point being attached to the fluid diaphragm;

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.

In another embodiment of the invention, there is a fluidic energy transfer device comprising:

a fluid chamber having an inner wall shaped so as to form a chamber volume and having an opening;

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;

a fluid within the fluidic chamber;

a fluidic load comprising said fluid;

a fluid spring comprising the fluid within said fluidic chamber;

a mechanical spring comprising said diaphragm; and

a bender actuator having an attachment point being attached to said fluidic diaphragm;

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.

In another embodiment of the invention, there is a fluid energy transfer device comprising:

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;

a bender actuator; wherein

the bender actuator is attached to the fluid diaphragm to form a bender-diaphragm 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 only due to the frequency of 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, and is exemplary about an order of magnitude greater than the distance of peak-to-peak bending.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

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;

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;

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;

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;

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;

FIG. 6 is a cross-sectional view an embodiment of the present invention having an axial alignment disk that may improve axial stability;

FIG. 6a is a cross-sectional view an another embodiment of the present invention;

FIG. 7 is a cross-sectional view of a reaction-drive pump embodiment of the present invention;

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;

FIG. 9 is a cross-sectional view of a reaction-drive pump embodiment of the present invention that provides reduced clearance volume;

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;

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;

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;

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;

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;

FIG. 15 is a cross-sectional view of a synthetic-jet embodiment of the present invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

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.

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_o=(½π)(K/M)^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_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_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.

If a drive frequency f is chosen to be near or equal to the system's fundamental resonant frequency f_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.

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× greater than the piezo bender displacement. Depending on the tuning of the system, displacement amplifications higher and even much higher than 15× may be provided, as well as amplifications that are lower and even much lower than 15×. The resonant displacement-amplification of a bender actuator comprises the characteristic dynamics of the present invention and is referred to herein as “reaction-drive.”

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.

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

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.

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.

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_o=(½π)(K/M)^1/2 of the system resonance.

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 θ, where θ is the time phase angle between a time varying force F(t)=F cos(ωt) and the resulting velocity V of the driven component so that the delivered power is FV cos θ. For maximum power transfer to the load, the ideal power factor is unity, implying that θ is zero. For a given power-delivery design target, if the power factor cos θ 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 θ 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 θ as close to zero as possible.

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_D and a reaction mass M_R. M_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_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_D and M_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_R/M_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_R is increased from a value of zero, while holding M_D constant, transduction efficiency generally increases and power transfer can be found to reach a maximum at some value of M_R/M_D. Performance may be enhanced by keeping the magnitude of M=(M_R+M_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.

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 θ 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 θ. In these discussions, the oscillation of the pump body in response to the diaphragm reaction forces must also be considered.

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 θ.

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.

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_R/M_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.

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

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.

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.

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.

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.

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.

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_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

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.

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.

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.

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_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_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.

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.

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.

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.

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

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.

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.

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.

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

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_s+V_c)/V_c where V_s is swept volume and V_c is clearance volume. The clearance volume is the volume of the compression chamber when the diaphragm is at the top of its stroke.

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 ⅓ of the swept volume. For applications where no pressure lift is required the design of pump 79 may provide the needed performance.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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

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_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 φ between V(t) and I(t). Microprocessor 258 then calculates the electrical power factor cos φ and then calculates the delivered electrical power P=V(t)·I(t)·cos φ. The delivered electrical power P reaches a maximum at the system resonance frequency f_o. Thus microprocessor 258 keeps the drive frequency f close to the system resonance frequency f_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.

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.

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.

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_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 φ between the respective V(t) and I(t) of bender actuators 280 and 282. Microprocessor 268 then calculates the electrical power factor cos φ and then calculates the delivered electrical power P=V(t)·I(t)·cos φ for each bender actuator. The delivered electrical power P reaches a maximum at the system resonance frequency f_o. Thus microprocessor 268 keeps the drive frequency f of function generator 270 close to the system resonance frequency f_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.

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

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.

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

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.

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.

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.

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.

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.

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.