Patent Application
20120181360
The present disclosure relates generally to synthetic jet ejectors, and more particularly to systems and methods for preventing dust and ambient particles from contaminating synthetic jet ejectors.
A variety of thermal management devices are known to the art, including conventional fan based systems, piezoelectric systems, and synthetic jet ejectors. The latter type of system has emerged as a highly efficient and versatile solution, especially in applications where thermal management is required at the local level.
Various examples of synthetic jet ejectors are known to the art. Earlier examples are described in U.S. Pat. No. 5,758,823 (Glezer et al.), entitled “Synthetic Jet Actuator and Applications Thereof”; U.S. Pat. No. 5,894,990 (Glezer et al.), entitled “Synthetic Jet Actuator and Applications Thereof”; U.S. Pat. No. 5,988,522 (Glezer et al.), entitled Synthetic Jet Actuators for Modifying the Direction of Fluid Flows”; U.S. Pat. No. 6,056,204 (Glezer et al.), entitled “Synthetic Jet Actuators for Mixing Applications”; U.S. Pat. No. 6,123,145 (Glezer et al.), entitled Synthetic Jet Actuators for Cooling Heated Bodies and Environments”; and U.S. Pat. No. 6,588,497 (Glezer et al.), entitled “System and Method for Thermal Management by Synthetic Jet Ejector Channel Cooling Techniques.
Further advances have been made in the art of synthetic jet ejectors, both with respect to synthetic jet ejector technology in general and with respect to the applications of this technology. Some examples of these advances are described in U.S. 20100263838 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”; U.S. 20100039012 (Grimm), entitled “Advanced Synjet Cooler Design For LED Light Modules”; U.S. 20100033071 (Heffington et al.), entitled “Thermal management of LED Illumination Devices”; U.S. 20090141065 (Darbin et al.), entitled “Method and Apparatus for Controlling Diaphragm Displacement in Synthetic Jet Actuators”; U.S. 20090109625 (Booth et al.), entitled Light Fixture with Multiple LEDs and Synthetic Jet Thermal Management System“; U.S. 20090084866 (Grimm et al.), entitled Vibration Balanced Synthetic Jet Ejector”; U.S. 20080295997 (Heffington et al.), entitled Synthetic Jet Ejector with Viewing Window and Temporal Aliasing”; U.S. 20080219007 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. 20080151541 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. 20080043061 (Glezer et al.), entitled “Methods for Reducing the Non-Linear Behavior of Actuators Used for Synthetic Jets”; U.S. 20080009187 (Grimm et al.), entitled “Moldable Housing design for Synthetic Jet Ejector”; U.S. 20080006393 (Grimm), entitled Vibration Isolation System for Synthetic Jet Devices”; U.S. 20070272393 (Reichenbach), entitled “Electronics Package for Synthetic Jet Ejectors”; U.S. 20070141453 (Mahalingam et al.), entitled “Thermal Management of Batteries using Synthetic Jets”; U.S. 20070096118 (Mahalingam et al.), entitled “Synthetic Jet Cooling System for LED Module”; U.S. 20070081027 (Beltran et al.), entitled “Acoustic Resonator for Synthetic Jet Generation for Thermal Management”; U.S. 20070023169 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”; U.S. 20070119573 (Mahalingam et al.), entitled “Synthetic Jet Ejector for the Thermal Management of PCI Cards”; U.S. 20070119575 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; U.S. 20070127210 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; U.S. 20070141453 (Mahalingam et al.), entitled “Thermal Management of Batteries using Synthetic Jets”; U.S. Pat. No. 7,252,140 (Glezer et al.), entitled “Apparatus and Method for Enhanced Heat Transfer”; U.S. Pat. No. 7,606,029 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; U.S. Pat. No. 7,607,470 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; U.S. Pat. No. 7,760,499 (Darbin et al.), entitled “Thermal Management System for Card Cages”; U.S. Pat. No. 7,768,779 (Heffington et al.), entitled “Synthetic Jet Ejector with Viewing Window and Temporal Aliasing”; U.S. Pat. No. 7,784,972 (Heffington et al.), entitled “Thermal Management System for LED Array”; and U.S. Pat. No. 7,819,556 (Heffington et al.), entitled “Thermal Management System for LED Array”.
In one aspect, a synthetic jet ejector is disclosed which comprises a housing having an orifice defined in a wall thereof from which a synthetic jet is emitted, and a barrier disposed about said orifice. The barrier has a first end (disposed proximal to said orifice) which has a first perimeter, and a second end (disposed distal to said orifice) which has a second perimeter. The second perimeter has a larger circumference than said first perimeter.
In another aspect, a synthetic jet ejector is disclosed which comprises (a) a housing; (b) a synthetic jet actuator disposed within said housing and comprising a diaphragm, a magnet and a pot, wherein said magnet and pot are disposed on a first side of said diaphragm; and (c) a porous member disposed within said housing on said first side of said diaphragm.
In another aspect, a synthetic jet ejector is disclosed which comprises a housing having a first compartment with a first diaphragm disposed therein and a second compartment with a second diaphragm disposed therein. The first diaphragm separates said first compartment into first and second sub-compartments, and the second diaphragm separates said second compartment into third and fourth sub-compartments. The second and fourth sub-compartments are in fluidic communication with each other by way of a conduit. The first sub-compartment has a first aperture in fluidic communication therewith from which a first synthetic jet is ejected, and the third sub-compartment has a second aperture in fluidic communication therewith from which a second synthetic jet is ejected.
In a further aspect, a synthetic jet ejector is disclosed which comprises (a) a housing equipped with first and second apertures; (b) first, second, third and fourth diaphragms, disposed within said housing, which divide the interior space of said housing into first, second, third, fourth and fifth compartments, wherein said second compartment is disposed between, and in fluidic communication with, said first and second diaphragms and is further in fluidic communication with said first aperture, and wherein said fourth compartment is disposed between, and in fluidic communication with, said third and fourth diaphragms and is further in fluidic communication with said second aperture; and (c) a conduit in fluidic communication with said first and fifth compartments.
In still another aspect, a synthetic jet ejector is disclosed which comprises (a) a first actuator comprising a first diaphragm driven by a first coil, wherein said first coil is disposed on a first side of said first diaphragm; (b) a second actuator comprising a second diaphragm driven by a second coil, wherein said second coil is disposed on a first side of said second diaphragm; and (c) an airtight enclosure which encloses said first and second coils; wherein at least one of said first and second diaphragms is in fluidic communication with the ambient environment.
In yet another aspect, a synthetic jet ejector is disclosed which comprises (a) a synthetic jet actuator comprising a first housing equipped with a first aperture and having a first diaphragm disposed therein; (b) a second housing equipped with an inlet and an outlet and having first and second compartments therein which are separated from each other by a second diaphragm, wherein said first compartment is in fluidic communication with said inlet, and wherein said second compartment is in fluidic communication with said outlet; and (c) a first conduit releasably attached to said first housing which fluidically connects said first aperture to said inlet.
In a further aspect, a synthetic jet ejector is disclosed which is equipped with an electrostatic dust guard. The synthetic jet ejector comprises (a) a synthetic jet actuator comprising a housing equipped with an aperture and having a diaphragm disposed therein; and (b) an electrical circuit equipped with a power source, a switch and an electrical conduit, wherein said switch transforms said electrical conduit between a first state and a second state, wherein said electrical conduit is disposed in the vicinity of said aperture, and wherein either (i) the electrical conduit is in a charged state when it is in the first state, and is in an uncharged state when it is in the second state, or (ii) the electrical conduit is in a charged state having a first polarity when it is in the first state, and is in a charged state having the opposite polarity when it is in the second state.
Prior to describing the devices and methodologies described herein, a brief explanation of a typical synthetic jet ejector, and the manner in which it operates to create a synthetic jet, may be useful.
The formation of a synthetic jet may be appreciated with respect to
The flexible diaphragm 18 may be controlled to move by any suitable control system 24. For example, the diaphragm 18 may be equipped with a metal layer, and a metal electrode may be disposed adjacent to but spaced from the metal layer so that the diaphragm 18 can be moved via an electrical bias imposed between the electrode and the metal layer. Moreover, the generation of the electrical bias can be controlled by any suitable device, for example but not limited to, a computer, logic processor, or signal generator. The control system 24 can cause the diaphragm 18 to move periodically, or modulate in time-harmonic motion, and force fluid in and out of the orifice 16.
Alternatively, a piezoelectric actuator could be attached to the diaphragm 18. The control system would, in that case, cause the piezoelectric actuator to vibrate and thereby move the diaphragm 18 in time-harmonic motion. The method of causing the diaphragm 18 to modulate is not particularly limited to any particular means or structure.
The operation of the synthetic jet actuator 10 will now be described with reference to
Synthetic jet ejectors represent a considerable advance in the art. This is especially true in thermal management applications, where they are frequently utilized, alone or in conjunction with a fan-based thermal management system, to provide quiet, energy efficient and localized cooling for LEDs, CPUs and other heat sources. Nonetheless, further improvement is required in these devices. In particular, it has been found that the performance of synthetic jet ejectors can degrade over time.
It has now been found that the presence of dust or particulate contaminants in the ambient environment is a significant cause of performance degradation in synthetic jet ejectors. It has further been found that this effect may be mitigated by sealing off the motor of the synthetic jet ejector from the ambient environment, or by providing a dust barrier (which may be physical or electrostatic) between the motor and the ambient environment.
Still referring to
For example, the barrier 211 could comprise one or more solid barriers, or may comprise various screens, meshes, fibers, or other porous materials. Also, in some embodiments, the barrier 211 may comprise multiple sections. For example, in some embodiments, the barrier 211 may comprise overlapping sheaths which are arranged like the petals of a flower. Moreover, each of these barriers 211 or screens may have a variety of shapes.
The barrier 211 may be frustoconical in shape, or may be concave or convex. Preferably, however, the barrier 211 has a first end having a first perimeter which is disposed proximal to the orifice 207, and a second end having a second perimeter which is distal to the orifice 207, and the second perimeter is preferably larger than the first perimeter. It is also preferred that the first end forms a fluidic seal with the housing 205 and is centered on the orifice 207, and that the second end is open to the ambient environment. It is further preferred that the barrier 211 curves outward in the direction going from the first end to the second end.
In some embodiments, the barrier 211 may have a major surface described by the rotation of a curve about an axis. The barrier 211 may also have a rotational axis of symmetry about the center of the orifice 207, and preferably, any plane which bisects the rotational axis of symmetry also bisects the barrier 211. In some embodiments, the barrier 211 may have a cross-sectional shape, in a plane parallel to the wall of the housing in which the orifice 207 is disposed, which is circular or elliptical.
As described above with reference to
It will, of course, be appreciated that a similar approach may be utilized if the aperture is in the form of a nozzle. In such an embodiment, the barrier 211 may extend from the body or the tip of the nozzle, or the nozzle may extend from the barrier 211. For example, in one implementation of the latter embodiment, the nozzle may extend from the barrier 211 in a manner analogous to the way a stamen extends from a flower.
The synthetic jet ejector 301 in this embodiment is equipped with a screen 311 or other barrier which is disposed on a side of the synthetic jet ejector 301 exposed to the ambient environment. The screen 311 is of appropriate mesh and construction to capture particles of dust and other contaminants. Since the screen 311 is placed in a region that is not exposed to high velocities, the pressure drop will not be as high as if the screen 311 is disposed at the aperture 307. This embodiment is particularly suitable for preventing the accumulation of dust and other contaminants on the magnet 317 and pot 319 of the synthetic jet ejector 301.
Various types of screening, mesh or other porous materials may be utilized in this embodiment or in the other embodiments disclosed herein (including, for example, any of the porous materials in the previously described embodiment). For example, such screening or mesh 311 may be metallic or polymeric, or may comprise a rigid or conformable fabric. Preferably, the synthetic jet ejector 301 operates to create a fluidic flow between the diaphragm and an aperture in the housing such that the fluidic flow passes through the screen 311 and creates a synthetic jet 309 at the aperture 307 or nozzle.
The first diaphragm 409 further divides the first compartment 407 into first 415 and second 417 sub-compartments. Similarly, the second diaphragm 413 further divides the second compartment 411 into third 419 and fourth 421 sub-compartments. A conduit 423 connects the second 417 and fourth 421 sub-compartments. The housing 403 is also equipped with first 425 and second 427 nozzles (which, in alternative embodiments, may be apertures), and the first 415 and third 419 sub-compartments are in fluidic communication with the first 425 and second 427 nozzles, respectively.
In operation, the first 409 and second 413 diaphragms are preferably operated out-of-phase, and more preferably 180° out-of-phase. Because the second 417 and fourth 421 sub-compartments are in fluidic communication with each other, these compartments may be hermetically sealed from the external environment, while still allowing the first 409 and second 413 diaphragms to vibrate as required to form synthetic jets 431 and 433 at nozzles 425 and 427, respectively. Advantageously, because the second 417 and fourth 421 sub-compartments are hermetically sealed from the external environment and house the magnets and pots that drive the diaphragms 409 and 413, these elements are protected from any dust or debris present in the external environment.
While the conduit 423 is depicted as being tubular, it will be appreciated that conduits of various geometries and dimensions may be utilized in embodiments of this type. It will further be appreciated that, in some implementations, multiple conduits 423 may be utilized. Moreover, the conduit 423 may be equipped with one or more heat fins on an interior or exterior surface thereof.
Notably, the second compartment 515 is bounded by the first 505 and second 507 diaphragms, and the fourth 519 compartment is bounded by the third 509 and fourth 511 diaphragms. Also, the first 513 and fifth 521 compartments are in fluidic communication with each other by way of a conduit 523.
In operation, the first 505 and second 507 diaphragms are preferably operated out-of-phase, and more preferably 180° out-of-phase, and the third 509 and fourth 511 diaphragms are preferably operated out-of-phase, and more preferably 180° out-of-phase. Even more preferably, both sets of diaphragms are operated out of phase, and most preferably, both sets of diaphragms are operated 180° out of phase. Because the first 513 and fifth 521 compartments are in fluidic communication with each other, these compartments may be hermetically sealed from the external environment, while still allowing the first 505 and fourth 511 diaphragms to vibrate. Similarly, the third compartment may be hermetically sealed from the external environment, while still allowing the second 507 and third 509 diaphragms to vibrate, by oscillating the second 507 and third 509 diaphragms out-of-phase.
Advantageously, because the first 513, third 517 and fifth 521 compartments are hermetically sealed from the external environment and house the magnets and pots that drive the diaphragms, these elements are protected from any dust, debris, salt, acid, or other contaminants present in the external environment. Moreover, the presence of the conduit 523 prevents the formation of an air spring in the sealed motor cavities. Here, it is to be noted that the presence of an air spring may alter the resonance of the synthetic jet ejector 501.
While the conduit 523 is depicted as being tubular, it will be appreciated that conduits of various geometries and dimensions may be utilized in embodiments of this type. It will further be appreciated that, in some implementations, multiple conduits 523 may be utilized. Moreover, the conduit 523 may be equipped with one or more heat fins on an interior or exterior surface thereof.
Each of the first 611 compartments contains the coil and other components of the actuator that cause the diaphragm 607 to vibrate. The first compartments 611 are sealed off from the ambient environment, but are in fluidic communication with each other by way of a conduit 619. In addition to reducing or eliminating pressure differences between the first compartments 607, the conduit 619 may also serve to dissipate heat to the ambient environment.
While the conduit 619 is depicted as being tubular, it will be appreciated that conduits of various geometries and dimensions may be utilized in embodiments of this type. It will further be appreciated that, in some implementations, multiple conduits 619 may be utilized. Moreover, the conduit 619 may be equipped with one or more heat fins on an interior or exterior surface thereof to aid in heat dissipation to the ambient environment.
A nozzle of this type may be incorporated into a wide variety of synthetic jet ejectors to keep dust and other particulate contaminants from entering the synthetic jet ejector during the inflow phase of operation (this phase is illustrated in
In some embodiments, an opposite strategy may be utilized. In particular, in some embodiments, a negative charge may be applied to the charge plates 705 during the inflow cycle of the synthetic jet ejector, and a positive (or zero) charge may be applied to the charge plates 705 during the outflow cycle. This may have the effect of repelling dust from the vicinity of the aperture during the inflow cycle.
In still other embodiments, a positive or negative charge may be applied to the charge plates 705 during both the inflow and outflow cycles (for example, a constant charge may be utilized). For example, a constant negative charge may be utilized to provide a constant repulsive charge for dust particles in the vicinity of the aperture while the synthetic jet ejector is in operation. Alternatively, a constant positive charge may be utilized to attract dust to the charge plates 705; in such an embodiment, the greater turbulence and directionality associated with the formation of a synthetic jet during the outflow cycle may be utilized to overcome the attractive charge, thus dislodging dust from the charge plates 705. Of course, it will be appreciated that various parameters may affect the operation of these embodiments including, but not limited to, the geometry and dimensions of the aperture, the dimensions and position of the plates, and the magnitude of the charge.
The operation of the synthetic jet ejector 801 of
Preferably, the dust trap 805 is operated with the same periodicity as the synthetic jet actuator 803 such that dust is collected on the dust trap 805 during the inflow stage 809 of the synthetic jet actuator 803, and is repelled during the outflow stage 911. Since the jet exhaust is much stronger than the intake suction, this mode of operation causes any dust which is trapped on the dust trap 805 to be blown a significant distance away from the dust trap 805 when it is released. Hence, the dust and contaminants do not become re-attracted to the dust trap 805, thus avoiding the creation of dust balls.
The motion of the actuators is indicated by the arrows. Preferably, the actuators are operated out of phase so that both are moving in the same direction, thus avoiding the creation of pressure differences within the enclosure 1111.
The synthetic jet actuator 1205 comprises an actuator 1207 and a first diaphragm 1209. The actuator 1207 is adapted to oscillate the first diaphragm 1209. A second or “slave” diaphragm 1211 is also disposed within the housing 1203 and is in fluidic communication with the first diaphragm 1209.
In operation, the actuator 1207 oscillates the first diaphragm 1209. Because the first diaphragm is in fluidic communication with the second diaphragm 1211 and the space between the two diaphragms is sealed, the oscillations in the first diaphragm 1209 cause corresponding oscillations in the second diaphragm 1211. As a result, a first synthetic jet 1213 is emitted from a first nozzle 1215 disposed on a first end of the housing 1203 through the action of the first diaphragm 1209, and a second synthetic jet 1217 is emitted from a second nozzle 1219 disposed on a first end of the housing 1203 through the action of the second diaphragm 1211. Of course, it will be appreciated that either or both of the first diaphragm 1209 and the second diaphragm 1211 may cause the formation of a plurality of synthetic jets at one or more nozzles or orifices. The first 1209 and second 1211 diaphragms may be the same or different, but preferably comprise the same material and have the same dimensions.
The synthetic jet actuator 1305 comprises an actuator 1307 and a first diaphragm 1309. The actuator 1307 is adapted to oscillate the first diaphragm 1309. A second or “slave” diaphragm 1311 is also disposed within the housing 1303 and is in mechanical communication with the first diaphragm 1309 by way of a plurality of struts 1310 or other connectors.
In operation, the actuator 1307 oscillates the first diaphragm 1309. Because the first diaphragm is in mechanical communication with the second diaphragm 1311, the oscillations in the first diaphragm 1309 cause corresponding oscillations in the second diaphragm 1311. As a result, a first synthetic jet 1313 is emitted from a first nozzle 1315 disposed on a first end of the housing 1303 through the action of the first diaphragm 1309, and a second synthetic jet 1317 is emitted from a second nozzle 1319 disposed on a first end of the housing 1303 through the action of the second diaphragm 1311.
Of course, it will be appreciated that either or both of the first diaphragm 1309 and the second diaphragm 1311 may cause the formation of a plurality of synthetic jets at one or more nozzles or orifices. Moreover, the first 1209 and second 1211 diaphragms may be the same or different, but preferably comprise the same material and have the same dimensions.
In operation, the synthetic jet ejector creates a fluidic flow into and out of the inlet 1413 of the conduit 1411, which causes the bladder 1409 to oscillate. The oscillation of the bladder 1409 causes the formation of a synthetic jet 1417 at the outlet 1415 of the conduit 1411.
The embodiment of
The above description of the present invention is illustrative, and is not intended to be limiting. It will thus be appreciated that various additions, substitutions and modifications may be made to the above described embodiments without departing from the scope of the present invention. Accordingly, the scope of the present invention should be construed in reference to the appended claims.
This application claims the benefit of U.S. Provisional Application No. 61/425,385, filed Dec. 21, 2010, having the same title and the same inventors, and which is incorporated herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61425385 | Dec 2010 | US |
