JP2012528980A - Fluid disc pump - Google Patents

Abstract

Disclosed is a pump having a substantially cylindrical shape and defining a cavity formed by side walls closed at both ends by end walls, wherein the cavity contains a fluid. The pump is further operatively associated with at least one of the end walls to produce a vibratory motion of the driven end wall, thereby generating a displacement vibration of the driven end wall within the cavity. It has an actuator. The pump further includes an isolator that is operatively associated with the periphery of the driven end wall to reduce attenuation of the displacement vibration.
[Selection]
1A

Description

  The illustrative embodiment of the present invention relates generally to a pump for fluids, and more particularly a pump wherein the pumping cavity is a substantially disk-shaped cylindrical cavity having substantially circular end walls and side walls. About.

  The generation of large amplitude pressure oscillations in closed cavities has received much attention in the fields of thermoacoustics and pump type compressors. Recent developments in nonlinear acoustics have allowed the generation of pressure waves of greater amplitude than previously thought possible.

  It is known to use acoustic resonances to achieve fluid pumping from defined inlets and outlets. This can be accomplished using a cylindrical cavity with an acoustic driver that drives an acoustic standing wave at one end. In such a cylindrical cavity, the acoustic pressure wave has a limited amplitude. Changing cross-sectional cavities such as cones, horn cones, spheres, etc. are used to achieve large amplitude pressure oscillations, thereby greatly improving pumping efficiency. In such a large-amplitude wave, the non-linear mechanism with energy dissipation is suppressed. However, large amplitude acoustic resonance has not been used until recently in disk-shaped cavities where radial (radial) pressure oscillations are excited. International Patent Application No. PCT / GB2006 / 001487 published as WO2006 / 111775 ('487 application) is a substantially disk-shaped cavity having a high aspect ratio (ie, the ratio of cavity radius to cavity height). Is disclosed.

  Such a pump comprises a substantially cylindrical cavity with side walls closed at each end by end walls. Such a pump also has an actuator that drives any one of the end walls to vibrate in a direction substantially perpendicular to the surface of the driven end wall. The spatial profile of the driven end wall motion is described to be matched to the spatial profile of the hydraulic oscillations in the cavity, which is referred to herein as mode matching. It is. When the pump is mode-matched, the work done on the fluid in the cavity by the actuator is applied constructively across the surface of the driven end wall, thereby improving the amplitude of pressure oscillations in the cavity. Achieve high pump efficiency. In pumps that are not mode matched, an area in the end wall where work done on the fluid by the end wall reduces rather than improves the amplitude of fluid pressure oscillations in the fluid in the cavity Can exist. In this way, the effective work done on the fluid by the actuator is reduced and the pump becomes less efficient. The efficiency of a mode matched pump depends on the boundary between the driven end wall and the side wall. The efficiency of such a pump is maintained by configuring such a boundary so as not to reduce or attenuate the movement of the driven end wall, thereby mitigating any reduction in the amplitude of fluid pressure oscillations in the cavity. It is desirable.

  According to one embodiment of the invention, the actuator of the pump described above is in the direction of the driven end wall in a direction substantially perpendicular to the end wall or in a direction substantially parallel to the long axis of the cylindrical cavity. An oscillating motion (“displacement vibration”) is produced (this vibration is hereinafter referred to as “axial vibration” of the driven end wall in the cavity). The axial vibration of the driven end wall generates a substantially proportional “pressure vibration” of the fluid in the cavity and is described in the first application described in the '487 application (incorporated herein by reference). Form a radial pressure distribution approximating that of a Bessel function of the kind. Such vibration is hereinafter referred to as “radial vibration” of the fluid pressure in the cavity. The portion of the driven end wall between the actuator and the side wall forms a boundary with the pump side wall that reduces the attenuation of the displacement vibrations and mitigates any decrease in pressure vibrations in the cavity. . The above portion is hereinafter referred to as an “isolator”. An illustrative embodiment of the isolator is operatively associated with the peripheral edge of the driven end wall to reduce the damping of the displacement vibration.

  According to another embodiment of the invention, the pump comprises a pump body having a substantially cylindrical shape defining a cavity formed by side walls closed at both ends by a substantially circular end wall. And at least one of the end walls is a driven end wall having a central portion and a peripheral edge adjacent the side wall, and the cavity contains fluid in use. The pump is further operatively associated with a central portion of the driven end wall and in a direction substantially perpendicular to the driven end wall and generally at the driven end wall. It has an actuator that generates a vibration motion having a maximum amplitude at the center, and thereby generates a displacement vibration of the driven end wall in use. The pump further includes an isolator that is operatively associated with the peripheral edge of the driven end wall to reduce attenuation of the displacement vibration due to the connection of the end wall to the side wall of the cavity. The pump further includes a first opening disposed substantially at the center of one of the end walls, and a second opening disposed at any other position in the pump body. The displacement vibration generates a radial vibration of fluid pressure in the cavity of the pump body, causing a fluid flow through the opening.

  Other objects, features and advantages of the illustrative embodiments will become apparent with reference to the drawings and detailed description which follow.

FIG. 1A shows a schematic cross-sectional view of a first pump supplying positive pressure, according to an illustrative embodiment of the invention. FIG. 1A (1) shows a graph of displacement vibration of the end wall driven by the first pump of FIG. 1A. FIG. 1A (2) shows a graph of pressure oscillations in the cavity of the first pump of FIG. 1A. FIG. 1B shows a schematic top view of the first pump of FIG. 1A. FIG. 2A shows a schematic cross-sectional view of a valve for use with a pump according to an illustrative embodiment of the invention. FIG. 2A (1) shows a cross section of the valve of FIG. 2A during operation. FIG. 2A (2) shows a cross section of the valve of FIG. 2A during operation. FIG. 2B shows a schematic top view of the valve of FIG. 2A. FIG. 3 shows a schematic cross-sectional view of a second pump supplying negative pressure according to an illustrative embodiment of the invention. FIG. 4 shows a schematic cross-sectional view of a third pump having a frustoconical base according to an illustrative embodiment of the invention. FIG. 5 shows a schematic cross-sectional view of a fourth pump including two actuators according to another illustrative embodiment of the invention. FIG. 6 shows an exploded schematic cross section of the edge of the pump of FIGS. 1A and 1B and shows a first embodiment of an isolator. FIG. 6A shows a graph of displacement vibration of the pump of FIG. FIG. 6B shows a graph of pressure oscillations in the cavity of the pump of FIG. FIG. 7A shows a schematic cross section of the pump of FIG. 3 and shows another embodiment of the isolator of FIG. FIG. 7B shows a schematic cross section of the pump of FIG. 3 and shows another embodiment of the isolator of FIG. FIG. 8 shows a schematic cross section of the pump of FIG. 1 and shows another embodiment of an isolator. FIG. 9 shows a schematic cross section of the pump of FIG. 1 and shows still another embodiment of the isolator. FIG. 10 shows a schematic cross section of the pump of FIG. 1 and shows still another embodiment of an isolator. FIG. 10A shows a graph of displacement vibration of the pump of FIG. FIG. 10B shows a graph of pressure oscillations in the cavity of the pump of FIG.

  In the following detailed description of several illustrative embodiments, reference is made to the accompanying drawings that form a part of these embodiments. In the drawings, there are shown by way of illustration specific preferred embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, other embodiments may be utilized, and the spirit and scope of the invention It is understood that logical, structural, mechanical, electrical, and chemical changes can be made without departing from the invention. To avoid detail not necessary to enable one skilled in the art to practice the embodiments described herein, the description may omit certain information known by those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of these illustrative examples is defined only by the appended claims.

  FIG. 1A is a schematic cross-sectional view of a pump 10 according to an illustrative embodiment of the invention. Referring also to FIG. 1B, the pump 10 has a pump body having a substantially cylindrical shape, the pump body being closed at one end by a base 18 and at the other end by an end plate 17 and an annular isolator. A cylindrical wall (cylindrical wall) 19 closed by 30 is included. The annular isolator 30 is disposed between the end plate 17 and the other end of the cylindrical wall 19 of the pump body. The cylindrical wall 19 and base 18 can be a single part having the pump body and can be attached to other components or systems. The cylindrical wall 19, the base 18, the end plate 17 and the inner surface of the isolator 30 form a cavity 11 in the pump 10, which has a side wall 14 closed at both ends by end walls 12 and 13. have. The end wall 13 is the inner surface of the base 18, while the side wall 14 is the inner surface of the cylindrical wall 19. The end wall 12 has a central portion corresponding to the inner surface of the end plate 17 and a peripheral edge portion corresponding to the inner surface of the isolator 30. Although the cavity 11 is substantially circular in shape, the cavity 11 may be oval or other shapes. The base 18 and cylindrical wall 19 of the pump body can be formed from any suitable rigid material including, but not limited to, metal, ceramic, glass or plastic.

  The pump 10 also has a piezoelectric disk 20 that is operatively connected to the end plate 17 to form an actuator 40 that is operatively connected to the central portion of the end wall 12 via the end plate 17. Are related. The piezoelectric disk 20 need not be formed from a piezoelectric material, and can be formed from any electrically active material such as, for example, an electrostrictive material or a magnetostrictive material. The end plate 17 preferably has the same bending rigidity as the piezoelectric disk 20 and can be formed from an electrically inactive material such as metal or ceramic. When the piezoelectric disk 20 is excited by an oscillating current, the piezoelectric disk 20 curves the end plate 17 in an attempt to expand and contract in the radial direction with respect to the long axis of the cavity 11, and thereby the end wall 12. Induces an axial deflection in a direction substantially perpendicular to the end wall 12. Alternatively, the end plate 17 can be formed of an electrically active material such as a piezoelectric material, a magnetostrictive material or an electrostrictive material. In other embodiments, the piezoelectric disk 20 may be replaced by a device that is in a force transfer relationship with respect to the end wall 12, such as a mechanical, magnetic, or electrostatic device, in which case the end wall 12 Can be formed as an electrically inactive or passive material layer that is driven into a vibrating state in a manner similar to that described above by such a device (not shown).

  The pump 10 further has at least two openings extending from the cavity 11 to the outside of the pump 10, at least a first of which is for controlling the flow of fluid through the openings. Valves may be included. While the opening containing the valve can be located in the cavity 11 at any position where the actuator 40 produces a pressure differential as will be described in detail later, one preferred embodiment of the pump 10 is the end wall 12, 13 with a valved opening located approximately in the center. The pump 10 shown in FIGS. 1A and 1B has a primary opening 16 that extends from the cavity 11 through the base 18 of the pump body at approximately the center of the end wall 13 and includes a valve 46. A valve 46 is mounted in the primary opening 16 and permits unidirectional fluid flow as indicated by the arrows, thus functioning as an outlet of the pump 10. The second opening 15 can be disposed at any position in the cavity 11 other than the position of the opening 16 including the valve 46. In one preferred embodiment of the pump 10, the second opening is disposed between the center of one of the end walls 12, 13 and the side wall 14. The embodiment of the pump 10 shown in FIGS. 1A and 1B has two secondary openings 15 extending between the center of the end wall 12 and the side wall 14 extending from the cavity 11 via the actuator 40. ing. These secondary openings 15 are not valved in this embodiment of the pump 10, but these openings can be valved to improve performance if necessary. In this embodiment of the pump 10, the primary opening 16 draws fluid into the cavity 11 of the pump 10 through the secondary opening 15 and through the primary opening 16 as indicated by the arrows. The valve is pumped from the cavity 11 to provide a positive pressure to the primary opening 16.

  Referring to FIG. 3, the pump 10 of FIG. 1 with an alternative configuration of the primary side opening 16 is shown. More specifically, the valve 46 'of the primary side opening 16' allows fluid to be drawn into the cavity 16 through the primary side opening 16 'and through the secondary side opening 15 as indicated by the arrows. 16 and thereby reversed to provide a suction or vacuum source for the primary opening 16 '. As used herein, the term “reduced pressure” broadly refers to a pressure that is lower than the ambient pressure where the pump 10 is located. The terms “vacuum” and “negative pressure” may be used to describe the reduced pressure, but the actual pressure drop may be significantly less than the pressure drop normally associated with a full vacuum. is there. The pressure is “negative” in the sense of gauge pressure. That is, the pressure is reduced below ambient atmospheric pressure. Unless indicated otherwise, the pressure values mentioned here are gauge pressures. Reference to an increase in vacuum typically refers to a decrease in absolute pressure, while a decrease in vacuum typically refers to an increase in absolute pressure.

  Valves 46 and 46 'allow fluid to flow in substantially one direction as described above. Valves 46 and 46 'allow ball valves, diaphragm valves, swing valves, duckbill valves, clapper valves, lift valves, or some other type of check valve or fluid to flow in substantially only one direction. It can be some other valve. Some valve types can regulate fluid flow by switching between open and closed positions. In order for such valves to operate at the high frequency generated by the actuator 40, the valves 46 and 46 'are extremely fast so that they can be opened and closed on a time scale significantly shorter than the time scale of the pressure change. Must have a response time. One embodiment of valves 46 and 46 'has a small inertia and thus uses a very light flap valve that can move at high speed in response to changes in relative pressure across the valve structure, Achieve this.

  Referring to FIG. 2A in more detail, a schematic cross-sectional view of one embodiment of a flap valve 50 mounted in the opening 16 (or 16 ') is shown. The flap valve 50 is disposed between the holding plate 52 and the sealing plate 53 and is biased (biased) toward the sealing plate 53 to a “closed” position that seals the flap valve 50 when not in use. The flap 51 is made to have. That is, the flap valve 50 is a normally closed type. The valve 50 is mounted in the opening 16 such that the upper surface of the holding plate 52 is preferably flush with the end wall 13 in order to maintain the resonance quality of the cavity 11. Both the holding plate 52 and the sealing plate 53 have vent holes 54 and 55, respectively, which vent holes from one side of the plate to the other as indicated by solid and dotted circles in FIG. 2B, respectively. It extends to. 2B is a top view of the flap valve 50 of FIG. 2A. The flap 51 also has vent holes 56 that are generally aligned with the vent holes 54 of the retaining plate 52 to form a passage through which fluid can flow as indicated by the dotted arrows in FIG. 2A (1). . However, as can be seen in FIGS. 2A and 2B, the vent holes 54 of the retaining plate 52 and the vent holes 56 of the flap 51 are not shown in the illustration of the sealing plate 53 blocked by the flap 51 when in the “closed” position as shown. It is not aligned with the vent 55 and therefore no fluid can flow through the flap valve 50.

  The operation of the flap valve 50 is a function of the change in direction of the fluid pressure differential (ΔP) across the flap valve 50. In FIG. 2A, a negative value (−ΔP) is assigned to the differential pressure, as indicated by an arrow pointing downward. This negative differential pressure (−ΔP) drives the flap 51 to the fully closed position as described above. In this case, the flap 51 is sealed against the sealing plate 53 and blocks the vent hole 55. The flow of fluid through the flap valve 50 is prevented. When the pressure difference between both ends of the flap valve 50 is reversed so as to become a positive pressure difference (+ ΔP) as shown by an arrow pointing upward in FIG. 2A (1), the biased flap 51 is The sealing plate 53 is moved toward the holding plate 52 to the “open” position. In this position, the above movement of the flap 51 unblocks the vent 55 of the sealing plate 53 so that the fluid is vented and then the aligned vent 56 and retention of the flap 51 as indicated by the dotted arrows. It becomes possible to flow through the vent holes 54 of the plate 52. When the differential pressure returns to a negative differential pressure (−ΔP) as indicated by the arrow pointing downward in FIG. 2A (2), the fluid is reversed via the flap valve 50 as indicated by the dotted arrow. This begins to flow in the direction, causing the flap 51 to return toward the closed position shown in FIG. 2A. In this way, the changing differential pressure is obtained when the flap valve 50 is repeatedly moved between the closed position and the open position, and when the differential pressure changes from a positive value to a negative value, the flap 51 is closed. Shut off fluid flow. It should be understood that the flap 51 may be biased toward the holding plate 52 to an “open” position when the flap valve 50 is not in use, depending on the application of the flap valve 50. . That is, in this case, the flap valve is a normally open type.

  Referring now to FIG. 4, a pump 70 according to another illustrative embodiment of the present invention is shown. The pump 70 is substantially similar to the pump 10 of FIG. 1 except that the pump body has a base 18 'with an upper surface forming an end wall 13' that is frustoconical. As a result, the height of the cavity 11 varies from the height at the side wall 14 to a smaller height between such end walls 12, 13 'at the center of the end walls 12, 13'. The frustoconical shape of the end wall 13 ′ is such that the pressure at the center of the cavity 11 where the height of the cavity 11 is smaller than the pressure at the side wall 13 of the cavity 11 where the height of the cavity 11 is larger. Strengthen. Therefore, when comparing a cylindrical cavity 11 with a frustoconical cavity 11 with equal central pressure amplitude, the frustoconical cavity 11 will usually have a smaller pressure at a position away from the center of the cavity 11. It is clear that it is deaf. That is, increasing the height of the cavity 11 acts to decrease the amplitude of the pressure wave. Both the viscous and thermal energy losses experienced during the vibration of the fluid in the cavity 11 increase with the amplitude of such vibration, so the design of the truncated cone cavity 11 is adopted for the efficiency of the pump 70. It is advantageous to reduce the amplitude of vibration away from the center of the cavity 11. In one illustrative example of a pump 70 having a cavity 11 diameter of about 20 mm, the height of the cavity 11 on the side wall 14 is about 1.0 mm and tapers to a height at the center of the end wall 13 ′ of about 0.3 mm. It becomes. Either one of the end walls 12, 13 or both end walls 12, 13 can have a truncated cone shape.

  Referring now to FIG. 5, a pump 60 according to another illustrative embodiment of the present invention is illustrated. The pump 60 is substantially similar to the pump 10 of FIG. 1 except that it includes a second actuator 62 that replaces the base 18 of the pump body. The actuator 62 includes a second disk 64 and an annular isolator 66 disposed between the disk 64 and the side wall 14. The pump 60 also has a second piezoelectric disk 68 operatively connected to the disk 64 to form an actuator 62. Actuator 62 is operatively associated with end wall 13 having the inner surface of disk 64 and isolator 66. The second actuator 62 also generates an oscillating motion of the end wall 13 in a direction substantially perpendicular to the end wall in a manner similar to that of the actuator 40 relative to the end wall 12 described above. When the actuators 40 and 62 are driven, a control circuit (not shown) for coordinating the axial displacement vibrations of these actuators is provided. These actuators are preferably driven so that they move at the same frequency but generally out-of-phase, i.e., the centers of the end walls 12, 13 first move towards each other and then move away.

The pump dimensions described here are preferably specified with respect to the relationship between the height (h) of the cavity 11 and the radius (r) of the cavity, which is the distance from the long axis of the cavity 11 to the side wall 14. The inequality of These formulas are as follows:
r / h>1.2; and h ² / r> 4 × 10 ⁻¹⁰ meters In one embodiment of the present invention, the ratio of the cavity radius to the cavity height (r / h) is the fluid in the cavity 11. When is a gas, it is between about 10 and about 50. In this example, the volume of the cavity 11 can be less than about 10 ml. Furthermore, the ratio of h ² / r is preferably in the range between about 10 ⁻³ meters and about 10 ⁻⁶ meters when the working fluid is a gas as opposed to a liquid.

  In one embodiment of the invention, the secondary opening 15 is located where the amplitude of the pressure oscillation in the cavity 11 is close to zero, i.e. at the "node" point of the pressure oscillation. When the cavity 11 is cylindrical, the radial dependence of the pressure oscillation can be approximated by a first-type Bessel function, and the radial node of the lowest order pressure oscillation in the cavity is the center of the end wall 12. Alternatively, it occurs at a distance of about 0.63r ± 0.2r from the long axis of the cavity 11. Thus, the secondary opening 15 is preferably at a radial distance (a) from the center of the end walls 12, 13 {where (a) ≈0.63r ± 0.2r}, ie the pressure oscillation. It is placed near the node point.

  Further, the pump disclosed herein preferably relates to the cavity radius (r) and the operating frequency (f), which is the frequency at which the actuator 40 oscillates to produce axial displacement of the end wall 12. The inequality of The inequality is as follows:

ここで、キャビティ１１内の作動流体における音速（ｃ）は、上記式に表されているように約１１５ｍ／ｓなる遅い速度（ｃ_ｓ）と約１,９７０ｍ／ｓに等しい速い速度（ｃ_ｆ）との間の範囲とすることができ、ｋ_０は定数である（ｋ_０＝３.８３）。アクチュエータ４０の振動運動の周波数は、好ましくは、キャビティ１１内の半径方向圧力振動の最低共振周波数に概ね等しくされるが、該最低共振周波数から２０％以内とすることもできる。キャビティ１１内の半径方向圧力振動の最低共振周波数は、好ましくは、５００Ｈｚより高いものとする。

Here, the sound velocity in the working fluid in the cavity. 11 (c), about as represented in the above formula 115m / s becomes slower rate _{(c s)} and about 1,970M / faster rate equal to s _{(c f} ) And k ₀ is a constant (k ₀ = 3.83). The frequency of the oscillatory motion of the actuator 40 is preferably approximately equal to the lowest resonance frequency of radial pressure oscillations in the cavity 11, but may be within 20% of the lowest resonance frequency. The lowest resonance frequency of radial pressure oscillations in the cavity 11 is preferably higher than 500 Hz.

  Referring now to the pump 10 in operation, the piezoelectric disk 20 is excited and expands and contracts radially relative to the end plate 17 which causes the actuator 40 to bend and thereby the driven end wall 12. Induced axial displacement in a direction substantially perpendicular to the driven end wall 12. Since the actuator 40 is operatively associated with the central portion of the end wall 12 as described above, the axial displacement vibration of the actuator 40 causes the axial displacement of the maximum amplitude vibration along the surface of the end wall 12. Vibration is generated, that is, anti-node vibration at approximately the center of the end wall 12. Returning to FIG. 1A, the displacement vibration of the pump 10 and the resulting pressure vibration described generally above are shown in greater detail in FIGS. 1A (1) and 1A (2), respectively. The phase relationship between the displacement vibration and the pressure vibration can vary, and no particular phase relationship should be suggested from any figure.

  FIG. 1A (1) illustrates one possible displacement profile showing axial vibration of the driven end wall 12 in the cavity 11. The solid curve and arrow represent the displacement of the driven end wall 12 at a point in time, while the dotted curve represents the displacement of the driven end wall 12 after a half cycle. The displacement shown in this and other figures is exaggerated. Since the actuator 40 is not rigidly attached at its periphery but is suspended by the isolator 30, the actuator 40 freely vibrates with respect to the center of gravity in its basic mode. In this basic mode, the amplitude of the displacement vibration of the actuator 40 becomes substantially zero at the annular displacement node 22 located between the center of the end wall 12 and the side wall 14. The amplitude of the displacement vibration at other points on the end wall 12 has an amplitude greater than zero as represented by a vertical arrow. The center displacement antinode 21 exists in the vicinity of the center of the actuator 40, while the peripheral displacement antinode 21 ′ exists in the vicinity of the circumference of the actuator 40.

  FIG. 1A (2) illustrates one possible pressure vibration profile showing the pressure vibration in the cavity 11 resulting from the axial displacement vibration shown in FIG. 1A (1). The solid curve and arrow represent the pressure at a point in time, while the dotted curve represents the pressure after half a cycle. In this mode and higher order modes, the amplitude of the pressure oscillation has a central pressure antinode 23 near the center of the cavity 11 and a peripheral pressure antinode 24 near the side wall 14 of the cavity 11. . The amplitude of the pressure oscillation is substantially zero at the annular pressure node 25 between the pressure antinodes 23 and 24. In the case of a cylindrical cavity, the radial dependence of the amplitude of pressure oscillation in the cavity 11 can be approximated by a first type Bessel function. Since the pressure vibration described above results from the radial movement of the fluid in the cavity 11, it is referred to as “radial pressure vibration” of the fluid in the cavity 11 as distinguished from the axial displacement vibration of the actuator 40.

  3 and 1A (2), the operation of the flap valve 50 described above in the pump 10 causes the fluid to flow in the direction indicated by the dotted arrow in FIG. A negative pressure is formed outside the side opening 16 ′. Referring to FIG. 3 in more detail, the flap valve 50 is drawn into the primary opening 16 'and fluid is drawn into the cavity 11 and through the primary opening 16' as indicated by the solid arrow. 15 is discharged from the cavity 11 via 15, and thereby, a reduced pressure source is formed in the primary side opening 16 ′. The fluid flow through the primary opening 16 'indicated by the solid arrow pointing upwards is the fluid flowing through the vent holes 54 and 55 of the flap valve 50 indicated by the dotted arrows in FIG. It corresponds to the flow of. As described above, the operation of the flap valve 50 is a function of the change in the direction of the pressure difference (ΔP) of the fluid across the flap valve 50. Such differential pressure (ΔP) is assumed to be substantially uniform across the entire surface of the retaining plate 52. Because its position corresponds to the central pressure antinode 23 shown in FIG. 1A (2), which is generally aligned with the primary opening 16 ′ in the base 18 of the pump 10, the pressure across the valve 50 is therefore free of space. This is because it is a good approximation that there is no change. When the pressure difference between both ends of the flap valve 50 is reversed so as to become a positive pressure difference (+ ΔP) as shown in FIG. 2A (1), the biased flap 51 is held away from the sealing plate 53. It is moved to the open position towards the plate 52. In this position, the movement of the flap 51 unblocks the vent 55 of the sealing plate 53, so that the fluid passes through the vent 55 as indicated by the dotted arrow, and then holds the vent 56 and the aligned flap 51. It is allowed to flow through the vents 54 of the plate 52. This forms a reduced pressure source outside the primary opening 16 'in the base 18 of the pump 10, as also indicated by the dotted arrows. When the differential pressure changes back to the negative differential pressure (−ΔP) as shown in FIG. 2A (2), the fluid begins to flow in the opposite direction through the flap valve 50 as indicated by the dotted line, This causes the flap 51 to return toward the closed position shown in FIG. 2A. Thus, when the differential pressure (ΔP) repeats the flap valve 50 between the closed position and the open position, the pump 10 forms a reduced pressure every half cycle in which the flap valve 50 is open.

  With further reference to FIGS. 1A (1) and 1A (2), the radial dependence of the amplitude of the axial displacement vibration of the actuator 40 (the “mode-shape” of the actuator 40) is desired in the cavity 11. It can be seen that the Bessel function of the first kind should be approximated to more closely match the radial dependence of the pressure vibration amplitude (the “mode shape” of the pressure vibration). Rather than mounting the actuator 40 rigidly around the circumference of the actuator, allowing the actuator to vibrate more freely with respect to its center of gravity, the mode shape of the displacement vibration is the pressure in the cavity 11. It substantially matches the mode shape of the vibration, thus achieving mode shape matching, or more simply mode matching. In this regard, the mode matching is not always perfect, but the axial displacement vibration of the actuator 40 and the corresponding pressure vibration in the cavity 11 have substantially the same relative phase over the entire surface of the actuator 40. Therefore, the radial position of the annular pressure node 25 of the pressure vibration in the cavity 11 and the radial position of the annular displacement node 22 of the axial displacement vibration of the actuator 40 substantially coincide with each other.

Since the actuator 40 vibrates with respect to the center of gravity (about the center of gravity), when the actuator 40 vibrates in the basic mode as illustrated in FIG. 1A (1), the radial position of the annular displacement node 22 is It is always located within the radius of the actuator 40. Thus, in order to ensure that the annular displacement node 22 coincides with the annular pressure node 25, the radius (r _act ) of the actuator is preferably an annular pressure node to optimize mode matching. Must be greater than 25 radii. Assuming that the pressure oscillation in the cavity 11 again approximates the first type Bessel function, the radius of the annular pressure node 25 is the radius from the center of the end wall 13 to the side wall 14, that is, the radius of the cavity 11 shown in FIG. r) of about 0.63. Therefore, the radius (r _act ) of the actuator 40 should preferably satisfy the inequality r _act ≧ 0.63r.

  Here, referring to FIG. 6, which is an exploded cross-sectional view of the edge of the pump 10 of FIG. 1, the isolator 30 is a flexible membrane 31, which is shown in FIG. 6A by the displacement 21 ′ of the peripheral displacement vibration. Bending and stretching in response to actuator 40 vibration as shown allows the edges of the actuator 40 to move freely as described above. The flexible membrane 31 provides a low mechanical impedance support between the actuator 40 of the pump 10 and the cylindrical wall 19, thereby damping the axial vibration 21 ′ of the peripheral displacement vibration of the actuator 40. By reducing, the potential damping effect of the side wall 14 on the actuator 40 is overcome. The flexible membrane 31 essentially minimizes energy being transferred from the actuator 40 to the sidewall 14 which remains substantially stationary. Thus, the annular displacement node 22 remains substantially aligned with the annular pressure node 25 so as to maintain the mode matching conditions of the pump 10. Thus, the axial displacement vibration of the driven end wall 12 efficiently generates pressure vibration from the central pressure antinode 23 (FIG. 1A) in the cavity 11 to the peripheral pressure antinode 24 in the side wall 14. to continue.

A simple sheet as described above having a uniform thickness (δ _m ) and Young's modulus (E _m ) across an annular gap (g) between the edge of the actuator 40 and the side wall 14 of the cavity 11; In the case of the flexible film 31 formed from the above, the force per unit length (F _stretch ) required to displace the edge of the flexible film 31 by the axial displacement (u) is approximated by the following equation: It is possible:

ここで、ｕ及びδ_ｍはｇより大幅に小さい。これは、アクチュエータ４０のディスク状実施例の縁部を同じ変位だけ曲げるのに要する単位長さ当たりの近似の力（Ｆ_bend）：

Here, u and δ _m are significantly smaller than g. This is an approximate force per unit length (F _bend ) required to bend the edge of the disk-like embodiment of the actuator 40 by the same displacement:

と比較することができ、ここで、アクチュエータ４０は実行ヤング率（Ｅ_ａ）、厚さ（δ_ａ）及び半径（Ｒ）を有する。アクチュエータ４０の縁部が自由に振動するためには、Ｆ_stretchはＦ_bendより大幅に小さくなければならず、このことは、上記の単純な可撓膜３１が、好ましくは、下記の不等式により特徴付けられる厚さ（δ_ｍ）を有さねばならないことを暗示する：

Where the actuator 40 has an effective Young's modulus (E _a ), thickness (δ _a ), and radius (R). In order for the edge of the actuator 40 to vibrate freely, F _stretch must be significantly less than F _bend , which is why the simple flexible membrane 31 described above is preferably characterized by the following inequality: Implying that it must have a thickness (δ _m ) attached:

アクチュエータ４０が、ｇ＝１ｍｍ、δ_ａ＝１ｍｍ、Ｒ＝１０ｍｍ及びｕ＝１０μｍなる全体寸法を持つスチール製端部プレート１７及び圧電ディスク２０を有するような一実施例において、この不等式は、カプトン（Kapton）からなる可撓膜３１の厚さが好ましくはδ_ｍ≪1,000ミクロンであり、スチールからなる可撓膜３１の厚さが好ましくはδ_ｍ≪100ミクロンであることを要する。

In one embodiment where the actuator 40 has a steel end plate 17 and a piezoelectric disk 20 with overall dimensions g = 1 mm, δ _a = 1 mm, R = 10 mm and u = 10 μm, this inequality is expressed in Kapton ( The thickness of the flexible membrane 31 made of Kapton) is preferably δ _m << 1,000 microns, and the thickness of the flexible membrane 31 made of steel is preferably δ _m << 100 microns.

  In one non-limiting example, the diameter of the actuator 40 can be 1-2 mm smaller than the diameter of the cavity 11 so that the flexible membrane 31 extends around the periphery of the end wall 12. The peripheral edge may be an annular gap (gap) of 0.5 to 1.0 mm between the edge of the actuator 40 and the side wall 14 of the cavity 11. In general, the annular width of the flexible membrane 31 is such that the diameter of the actuator approaches the diameter of the cavity so that the diameter of the annular displacement node 22 is approximately equal to the diameter of the annular pressure node 25. While it must be relatively small compared to the radius (r) of the cavity, it should be large enough to promote and not limit the vibration of the actuator 40. The flexible film 31 can be formed of a polymer sheet material having a uniform thickness such as PET or Kapton. In one embodiment, the flexible membrane 31 can be formed from a Kapton sheeting having a thickness less than about 200 microns. The flexible membrane 31 can also be formed from a thin metal sheet of uniform thickness, such as, for example, steel or brass or some other suitable flexible material. In other embodiments, the flexible membrane 31 can be formed from a steel sheet having a thickness of less than about 20 microns. The flexible membrane 31 can be formed of any other flexible material suitable for promoting the vibration of the actuator 40 as described above. The flexible membrane 31 can be glued, welded, clamped, soldered or otherwise attached to the actuator 40 depending on the material used, and the flexible membrane 31 is attached to the side wall 14. Similar or other methods can be used for attachment.

  The major component of the movement of the edge of the actuator 40 is substantially perpendicular to the driven end wall 12 or substantially parallel to the long axis of the cavity 11 (“axial movement”), The edge of the actuator 40 also has a small component “radial motion” that occurs in a plane perpendicular to the long axis of the cavity 11. For at least this reason, the flexible membrane 31 must also be designed to extend radially. Such radial stretching can be achieved by forming the actuator 40 from a thin elastic material as described above, or by the radial flexibility of the flexible membrane 31 to stretch and compress (ie, vibration of the actuator 40). Can be achieved by incorporating structural features into the flexible membrane 31 to improve the extensibility of the flexible membrane 31 with respect to the radial movement of the actuator 40 to further promote the motion.

  Referring to FIGS. 7A and 7B in more detail, additional embodiments of the flexible membrane 31 having structural features that improve the stretchability of the flexible membrane 31 to facilitate radial movement of the actuator 40 are shown. It is shown. Referring to FIG. 7A in more detail, a first embodiment 32 of a structurally modified flexible membrane is shown, which is an annular bellows extending between the actuator 40 and the side wall 14. (Concertina portion) 33 is included. The bellows portion 33 has an annular bend that appears as a wave in FIG. 7A in the flexible membrane 32, and these bends expand and contract like an accordion by the movement of the actuator 40. The bellows portion 33 of the flexible membrane 32 effectively reduces the radial stiffness of the flexible membrane 32, thereby improving the stretchability of the flexible membrane 32 and making the actuator 40 easier in the radial direction. Allows to stretch and contract.

  Referring to FIG. 7B in more detail, a second embodiment of a structurally modified flexible membrane 34 is shown, wherein the flexible membrane 34 is between each of the flexible membranes 34 between the actuator 40 and the sidewall 14. The annular semicircular grooves 35 are alternately arranged on the side (surface). The annular groove 35 of the flexible membrane 34 can be formed by chemical etching, polishing, or some similar method, or can be formed by lamination. The annular groove 35 of the flexible membrane 34 effectively reduces the radial stiffness of the flexible membrane 34, thereby improving the stretchability of the flexible membrane 34 and the radial direction of the actuator 40. Easy to stretch and shrink. Note that the structure shown in FIGS. 7A and 7B and similar structures may also advantageously reduce the force required to bend the isolators 32, 34 in the axial direction.

  The isolator 30 and the flexible films 31, 32, and 34 shown in the above figures are ring-shaped parts extending between the side wall 14 and the actuator 40, but the isolator 30 may have different shapes. It can also be supported in different ways by the cylindrical wall 19 without extending completely to the side wall 14 of the cavity 11. Referring to FIGS. 8 and 9, alternative embodiments of flexible membrane 31 are shown, which include flexible membranes 36 and 37 that function in a manner similar to other flexible membranes 31, 32, and 34, respectively. Contains. Referring to FIG. 8 in more detail, the flexible membrane 36 is formed in the shape of a disk, and the inner surface of the flexible membrane forms the end wall 12 rather than the end plate 17. The end plate 17 is shown remaining operatively connected to the upper surface of the flexible membrane 36. In the embodiment of FIGS. 8 and 9, end wall 12 still has a central portion operatively connected to actuator 40, and the peripheral portion functions as isolator 30 between side wall 14 and actuator 40. . As such, the flexible membrane 36 operates in a manner similar to that of the other flexible membranes 31, 32, and 34.

  Referring to FIG. 9 in more detail, the cylindrical wall 19 of the pump body includes a lip 19a that extends radially inward from the side wall 14 of the pump body. The inner surface of the lip 19 a facing the cavity 11 forms the outer surface of the peripheral edge located adjacent to the side wall 14 in the end wall 12. The flexible membrane 37 can be disk-shaped or ring-shaped as shown, and is attached to the inner surface of the lip 19a of the cylindrical wall 19 to form the remainder of the end wall 12 as described above. Regardless of the shape of the flexible membrane 37, the end wall 12 still has a central portion operatively connected to the actuator 40, and the peripheral edge is an isolator 30 between the actuator 40 and the lip 19 a of the cylindrical wall 19. Function as. As such, the flexible membrane 37 operates in a manner similar to that of the other flexible membranes 31, 32, and 34. The structure, suspension, and shape of the isolator 30 are not limited to these embodiments, and various changes and modifications can be made without departing from the spirit of the present invention described herein. It will be clear.

1-9, the side wall 14 extends continuously with the end walls 12 and 13 of the cavity 11, and the radius of the actuator 40 (r _act ) is the radius of the cavity 11 ( smaller than r). In such an embodiment, the sidewall 14 forms an uninterrupted surface from which the radial acoustic standing waves formed in the cavity 11 during operation are reflected. However, the radius (r _act ) of the actuator extends completely to the side wall 14 so that the radius is substantially equal to the radius (r) of the cavity, and the annular displacement node 22 of the displacement oscillation is the annular pressure node of the pressure oscillation. It would be desirable to ensure a tighter alignment with 25, thereby maintaining the aforementioned mode matching conditions more closely.

  Referring to FIG. 10 in further detail, yet another embodiment of the pump 10 is illustrated, in which the actuator 40 has the same radius as the diameter of the cavity 11 and the flexible membrane 31 shown in FIG. Are supported by a flexible membrane 38 having the same characteristics as The flexible membrane 38 must bend in response to the vibration of the actuator 40 to allow the edges of the actuator 40 to move freely, so that the cylindrical wall 19 of the pump body is the cylindrical wall. 19 has an annular step 19b extending radially outward from the side wall 14 to the annular edge 19c. The annular step 19c is cut deep enough in the upper surface of the cylindrical wall 19 to allow the actuator 40 to vibrate freely without disturbing the bending of the flexible membrane 38. . The step 19c must be deep enough to accept the bending of the flexible membrane 38, but not deep enough to significantly reduce the resonance quality of the cavity 11 described above.

As seen in FIGS. 10 and 10A, the driven end wall 12 has a flexible membrane 38 and a lower surface of the end plate 17 and has a radius (r _end ) greater than the radius of the cavity 11. . That is, r _end > r. Thus, the peripheral edge of the end wall 12 extends beyond the side wall 14 of the cavity 11. Referring to FIGS. 10A and 10B in more detail, the axial vibration of the actuator 10 and the corresponding pressure vibration in the cavity 11 continue to have substantially the same relative phase across the entire surface of the actuator 40, such displacement vibration. And the amplitude of the pressure oscillation is more closely proportional at the side wall 14. As a result, the radial position of the annular pressure node 25 of the pressure oscillation in the cavity 11 and the annular displacement node 22 of the axial vibration of the actuator 40 can be more closely matched, further improving mode matching.

  In order to ensure that the side wall 14 still forms a substantially uninterrupted surface in which the radial acoustic standing wave is reflected in the cavity 11, the depth of the step 19b is preferably as described above. As minimized. In one non-limiting example, the depth of the step 19b can be sized to maintain as much as possible the resonant quality of the cavity 11 of the pump. For example, the depth of the step portion 19 b can be 10% or less of the height of the cavity 11.

From the foregoing description, it will be apparent that an invention having great advantages has been provided. Further, the present invention shows only a few of the forms thereof, but the present invention is not limited to these, and various changes and modifications can be made without departing from the spirit of the present invention. Is possible.

Claims (52)

At least one of the end walls having a substantially cylindrical shape defining a cavity for containing fluid, the cavity being formed by side walls closed at both ends by a substantially circular end wall Is a driven end wall, and the driven end wall has a central portion and a pump body having a peripheral portion extending radially outward from the central portion of the driven end wall;
Operatively associated with the central portion of the driven end wall to cause an oscillating motion of the driven end wall, thereby substantially in the end wall of the driven end wall in use. An actuator that generates a displacement vibration in a direction perpendicular to a center of the driven end wall and an annular node between the side wall;
An isolator operatively associated with the peripheral edge of the driven end wall to reduce attenuation of the displacement vibration;
A first opening disposed at any position other than the position of the annular node in the cavity and extending through the pump body;
A second opening disposed at any position other than the position of the first opening in the pump body, and extending through the pump body;
A valve disposed in at least one of the first opening and the second opening;
And in use, the displacement vibration generates a corresponding radial pressure vibration of the fluid in the cavity of the pump body, causing a fluid flow through the first and second openings. .   The pump according to claim 1, wherein the ratio of the radius (r) of the cavity extending from the long axis of the cavity to the side wall to the height (h) of the side wall of the cavity is greater than about 1.2. pump. A pump according to claim 2, the height of the cavity (h) and the radius of the cavity (r) ^{further, h 2 / r> 4 ×} 10 -10 meters become pumps are related by the equation.   3. The pump according to claim 2, wherein the second opening is disposed on one of the end walls at a distance of about 0.63 (r) ± 0.2 (r) from the center of the end wall. Pump.   3. The pump according to claim 2, wherein the actuator drives the end wall associated with the actuator to generate the oscillating motion at a frequency (f). The pump according to claim 2, wherein the actuator drives the end wall associated with the actuator to generate the oscillating motion at a frequency (f), wherein the radius (r) is

A pump that is related to the frequency (f) by the formula: where c _s ≈115 m / s, c _r ≈1970 m / s, and k ₀ = 3.83.   The pump of claim 1, wherein the lowest resonant frequency of the radial pressure oscillation is higher than about 500 Hz.   2. The pump according to claim 1, wherein the frequency of the displacement vibration of the driven end wall is approximately equal to the lowest resonance frequency of the radial pressure vibration.   The pump according to claim 1, wherein the frequency of the displacement vibration of the driven end wall is within 20% of the lowest resonance frequency of the radial pressure vibration.   2. The pump according to claim 1, wherein the displacement vibration of the driven end wall has a mode shape matched to the radial pressure vibration.   The pump according to claim 1, wherein the valve allows the fluid to flow substantially unidirectionally through the cavity.   The pump according to claim 1, wherein the isolator is a flexible membrane.   13. A pump according to claim 12, wherein the flexible membrane is formed from plastic.   14. The pump according to claim 13, wherein the flexible membrane has an annular width between about 0.5 mm and 1.0 mm, and the thickness of the flexible membrane is less than about 200 microns.   The pump according to claim 12, wherein the flexible film is formed of metal.   16. The pump of claim 15, wherein the flexible membrane has an annular width between about 0.5 mm and 1.0 mm, and the thickness of the flexible membrane is less than about 20 microns.   2. The pump according to claim 1, wherein the side wall of the pump has a recess extending radially outward in the cavity adjacent to at least one of the end walls.   The pump of claim 2, wherein the ratio of r / h is between about 10 and about 50 when the fluid used in the cavity is a gas. A pump according to claim 3, when the fluid used within the cavity is a gas, the ratio of the h ^{2 /} r is between 10 ^-3 meters and about 10 ^-6 meters pump .   The pump of claim 2, wherein the cavity volume is less than about 10 ml. The pump according to claim 1,
A second actuator operatively associated with a central portion of the other end wall of the end walls to produce an oscillating motion in a direction substantially perpendicular to the end wall of the other end wall;
A second isolator operatively associated with a peripheral edge of the other end wall to reduce damping of vibrational motion of the other end wall by the side wall in the cavity;
Further having a pump.   The pump according to claim 2, wherein the radius of the actuator is 0.63 (r) or more.   23. The pump according to claim 22, wherein the radius of the actuator is equal to or less than the radius (r) of the cavity.   The pump according to claim 1, wherein the actuator includes a piezoelectric component that causes the oscillating motion.   The pump according to claim 1, wherein the actuator includes a magnetostrictive component that supplies the oscillating motion. A cavity having a substantially cylindrical shape for containing a fluid with side walls closed by two end faces, said cavity having a height (h) and a radius (r), said height ( a pump body having a ratio of said radius (r) to h) greater than about 1.2;
An actuator that is operatively associated with a central portion of one of the end faces and that generates an oscillating motion of the end face in use with an annular node between the center of the end face and the sidewall. When,
An isolator operatively associated with a peripheral edge of the end face to reduce damping of the oscillatory motion;
A first opening disposed at any position other than the position of the annular node in the cavity and extending through the pump body;
A second opening disposed at any position other than the position of the first opening in the pump body, and extending through the pump body;
A valve disposed in at least one of the first opening and the second opening to allow the fluid to flow through the cavity in use;
Having a pump.   27. The pump according to claim 26, wherein the oscillating motion generates radial pressure oscillations of the fluid in the cavity, causing fluid flow through the first opening and the second opening.   28. The pump according to claim 27, wherein the lowest resonant frequency of the radial pressure oscillation is higher than about 500 Hz.   28. A pump according to claim 27, wherein the frequency of the oscillating motion is approximately equal to the lowest resonance frequency of the radial pressure oscillation.   28. A pump according to claim 27, wherein the frequency of the oscillating motion is within 20% of the lowest resonant frequency of the radial pressure oscillation.   28. A pump according to claim 27, wherein the oscillating motion is modal matched to the radial pressure oscillation.   27. A pump according to claim 26, wherein the side wall of the pump has a recess extending radially outwardly in the cavity adjacent to at least one of the end walls. 27. A pump according to claim 26, wherein the height (h) of the cavity and the radius (r) of the cavity are further related by the formula h ² / r> 4 × 10 ⁻¹⁰ meters. 27. The pump of claim 26, wherein the actuator drives the end face of the cavity associated with the actuator to generate the oscillating motion at a frequency (f), wherein the radius (r) is

A pump that is related to the frequency (f) by the formula: where c _s ≈115 m / s, c _r ≈1970 m / s, and k ₀ = 3.83.   27. The pump according to claim 26, wherein the isolator is a flexible membrane.   36. The pump according to claim 35, wherein the flexible membrane is formed from plastic.   37. The pump of claim 36, wherein the flexible membrane has an annular width between about 0.5 mm and 1.0 mm, and the thickness of the flexible membrane is less than about 200 microns.   36. The pump according to claim 35, wherein the flexible membrane is made of metal.   40. The pump of claim 38, wherein the flexible membrane has an annular width between about 0.5 mm and 1.0 mm, and the thickness of the flexible membrane is less than about 20 microns.   27. The pump according to claim 26, wherein the actuator has a radius of 0.63 (r) or more.   41. A pump according to claim 40, wherein the radius of the actuator is less than or equal to the radius (r) of the cavity.   27. The pump according to claim 26, wherein the second opening is disposed at one of the end faces at a distance of about 0.63 (r) ± 0.2 (r) from the center of the end face. .   27. A pump according to claim 26, wherein the valve allows the fluid to flow substantially unidirectionally through the cavity.   27. The pump of claim 26, wherein the ratio of r / h is in the range between about 10 and about 50 when the fluid used in the cavity is a gas. A pump according to claim 26, when the fluid used within the cavity is a gas, the ratio of the h ^{2 /} r is between 10 ^-3 meters and about 10 ^-6 meters pump .   27. The pump of claim 26, wherein the cavity volume is less than about 10 ml. The pump according to claim 26,
A second actuator operatively associated with a central portion of the other end face of the cavity to cause an oscillating motion of the other end face;
A second isolator operatively associated with a peripheral edge of the other end face to reduce damping of the oscillatory motion;
Further having a pump.   27. The pump according to claim 26, wherein the actuator includes a piezoelectric component that causes the oscillating motion.   27. A pump according to claim 26, wherein the actuator comprises a magnetostrictive component for supplying the oscillatory motion.   27. The pump according to claim 26, wherein one end face of the end faces of the cavity has a truncated conical shape, and the height (h) of the cavity is substantially equal to the center of the one end face. A pump that varies from a height of 1 to a second height that is less than the first height adjacent to the sidewall.   27. The pump according to claim 26, wherein one end face of the end faces of the cavity has a truncated conical shape, and the height (h) of the cavity is substantially equal to the center of the one end face. A pump that increases from a height of 1 to a second height adjacent to the side wall.   52. The pump according to claim 51, wherein a ratio of the first height to the second height is about 50% or more.

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