TUNED MICRO CHECK VALVES AND PUMPS

Abstract

A fluid pump for pumping a fluid between a fluid inlet and a fluid outlet has a chamber with an inlet and an outlet. At least one flow restricting element is disposed at a flow line portion and is configured to resonate along a continuum of states between a first end state and a second end state to thereby affect fluid flow profile through said inlet or said outlet. While resonating the element transitions through a range of states differing in the flow they permit. A driver is configured to modulate conditions in the chamber or on the at least one flow restricting element at a characteristic frequency profile, thereby inducing the at least one flow restricting element to resonate between the first and second states at about said characteristic frequency profile.

Claims

1. A pump 100 for providing fluid pressure; said pump 100 comprising: a pump chamber 20; a driver 30 configured to modulate a volume of said pump chamber 20 at a characteristic frequency; a first valve 110 adapted for controlling flow between said chamber 20 and external environment, said first valve adapted for intermittently blocking and unblocking said flow; said first valve having a resonance frequency matching said characteristic frequency of said driver.

2. The pump of claim 1, wherein the volume of said chamber is between 50 nl to 50 μl.

3. The pump of claim 1, wherein said valve is a check valve.

4. The pump of claim 1, wherein said driver 30 includes a diaphragm.

5. The pump of claim 1, further wherein said first valve is an inlet valve adapted for inflow to said chamber 20 and further comprising: an outlet check valve 120 adapted for outflow from said chamber 20.

6. The pump of claim 5, where each of said first valve and said outlet valve comprises: a passage 42/62 adapted for conducting a fluid flow and a flap 40/60 adapted for intermittently blocking said fluid flow.

7. The pump of claim 6, wherein said flap 40/60 has a geometric shape and a mass matched with resonant coherent oscillation in said passages 42 and 62, respectively, when excited by said driver 30 such that said flap blocks said fluid flow in an antiphase manner between said inlet valve and said outlet valve.

8. The pump according to claim 1, wherein said driver 30 is configured to oscillate said chamber volume at an audible frequency and first valve is configured for resonant oscillation.

9. The pump according to claim 1, wherein said valve includes a resonantly oscillating flap 40/60.

10. The pump according to claim 9, wherein said flap 40/60 is configured for partially blocking a passage 42/62 with a gap 47/67 between a fixed member 45/65 and said flap 40/60 being sufficiently narrow for blocking of said passage 42/62 and generating a fluid outflow; said gap 47/67 providing sufficient clearance for contact-free resonant oscillation of said flap 40/60.

11. The pump according to claim 9, wherein said flap is of a tapered shape.

12. The pump according to claim 1, wherein said flap includes a resonantly oscillating piston 220 connected to an abutment 250 by means of a spring 240.

13. A method of generating fluid pressure, said method comprising the steps of: oscillating a volume of a chamber at a characteristic frequency; resonating a first valve at an inlet to said chamber at said characteristic frequency to open when the volume of the chamber is increasing and close when the volume of the chamber is decreasing.

14. The method of claim 13, further comprising: resonating a second valve flap at an outlet to said chamber at said characteristic frequency to close when the volume of the chamber is decreasing and open when the volume of the chamber is increasing.

15. The method of claim 13, where said resonating is achieved by elastically deforming a valve flap at a resonance frequency thereof.

16. The method of claim 13, where said oscillated is achieved by elastically deforming a drive membrane 30.

17. The method of claim 13, wherein said oscillating and said resonating are at a frequency out of audible frequencies.

18. The method of claim 13, wherein said step of resonating of said valve is between a partially open and a fully closed condition.

19. The method of claim 13, wherein said step of resonating of said valve is performed by a resonantly oscillating piston 220 connected to an abutment 250 by means of a spring 240.

20. A pressure-responsive valve comprising a valve chamber defined by a chamber wall having an opening fluidly interconnecting said chamber with environment; and a valve flap configured for resonant vibration alternatively opening and blocking said opening.

21. The pressure responsive valve of claim 20, wherein said flap has a distal portion which is configured to move partially parallel to said chamber wall; said distal portion having a hole such vibration of said flap under changes of a pressure within said chamber, alternatively aligns said hole to said opening to permit fluid communication of said valve chamber with the environment and moves said hole out of alignment with said opening to block fluid communication of said valve chamber with the environment.

22. A pressure-responsive valve comprising a valve chamber defined by a chamber wall having a plurality of openings fluidly interconnecting said chamber with an external environment; and a valve flap configured for resonant vibration sequentially opening and blocking each said opening of said multiple openings.

23. The pressure responsive valve of claim 22, wherein said flap has a distal portion which is configured to move partially parallel to said chamber wall; said distal portion having a hole such that vibration of said flap under changes of a pressure within said chamber, sequentially aligns said hole to a first opening of said plurality of openings to permit fluid communication through said first opening and moves said hole out of alignment with said first opening to block fluid communication through said first opening while aligning said hole to a second opening of said plurality of openings to permit fluid communication through said second opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0060] FIGS. 1A-1C are schematic illustrations of a longitudinal cross section of an example of an embodiment of the fluid pumping arrangement according to an aspect of the present disclosure.

[0061] FIG. 2 is a schematic illustration of a longitudinal cross section exemplifying the different states of the flow restricting element of the present disclosure;

[0062] FIG. 3 is a schematic illustration of a longitudinal cross section exemplifying the geometric profile of the flow restricting element of the present disclosure;

[0063] FIG. 4 is a cross-sectional view of a cylindrical valve with an oscillating piston in accordance with an embodiment of an aspect of the present disclosure;

[0064] FIG. 5 is an isometric view of a cylindrical valve with an oscillating piston in accordance with an embodiment of an aspect of the present disclosure;

[0065] FIG. 6 is a schematic view of a one-way valve in accordance with an embodiment of an aspect of the present disclosure;

[0066] FIG. 7 is a schematic view of a two-way valve in accordance with an embodiment of an aspect of the present disclosure;

[0067] FIG. 8 is a block diagram of a valve in accordance with an embodiment of an aspect of the present disclosure; and

[0068] FIG. 9 is a flow chart illustration of a method of controlling fluid flow in accordance with an embodiment of an aspect of the present disclosure.

DETAILED DESCRIPTION

[0069] Reference is made to FIGS. 1A-1C, which are schematic illustrations of a longitudinal cross section of a non-limiting example of a pump according to an aspect of the present disclosure.

[0070] FIG. 1A shows a pump 100, having a housing 10 defining a pump chamber 20, a fluid inlet 50 and a fluid outlet 70. The pump chamber 20 is defined downstream the fluid inlet 50 and upstream the fluid outlet 70. An inlet flow restricting element 40 is disposed at a first flow path portion 110 so as to control the inflow of fluid into the chamber 20 through a flow line portion 42. An outlet flow restricting element 60 is disposed at a second flow path portion 120 so as to control the outflow of fluid from the chamber 20 through a flow line portion 62. Each of the inlet and outlet flow restricting elements 40 and 60 are configured to continuously oscillate between a first end state 40o/60o and a second end state 40i/60i (the first and second end states are shown in dash lines), wherein a transition state, 43/63, optionally being resting, neutral state is defined between the first end state 40o/60o and the second end state 40i/60i. The inlet and outlet flow restricting elements 42 and 62 are either configured to (i) rotate about axes defined by the attachment profile of the restricting elements to the housing thereby allowing the oscillation between the first and second positions, or (ii) to elastically deform in response to forces applied thereon. The inlet flow restricting element 42 is transitionable between at least two ranges of states, a first, flow permitting range of states and a second, flow restricting range of states. At this non-limiting example, the flow permitting range of states is defined between the transition state 43 and the second end state 40i, and the flow restricting range of states is defined between the transition state 43 and the first end state 40o. The outlet flow restricting element 62 is transitionable between at least two ranges of states, a first, flow permitting range of states and a second, flow restricting range of states. At this non-limiting example, the flow permitting state is defined between the transition state 63 and the first end state 60o and the flow restricting state is defined between the transition state 63 and the second end state 60i. The geometric profile of the walls of the housing resulting the transition between the states according to the position of the oscillation of the flow restricting elements. Along the range of the flow restricting states of the flow restricting elements, the geometric profile of the walls 45/65 is designed to maintain a narrow gap 47 between the flow restricting element and the wall, thus substantially restricting the flow into and out of the chamber 20. The geometric profile of the walls along the range of the flow permitting states of the flow restricting elements is designed to maintain a relatively large gap allowing non-restrictive flow into and out of the chamber.

[0071] A driver 30 is configured to modulate the volume within the chamber 20 between a first volume resulting from a first driver state 30o and a second volume resulting from a second driver state 30i at a resonating characteristic frequency profile to thereby cause the flow restricting elements 42/62 to matchingly resonate at the characteristic frequency profile and therefore continuously transition between the flow restricting state and the flow permitting state. The driver 30 in this non-limiting example comprises a resonating membrane or diaphragm that is driven at the characteristic frequency profile between the first and second driver states 30o and a second driver state 30i, the second driver state 30i results in a chamber volume smaller than that resulted by the first driver state 30o.

[0072] The inlet and outlet flow restricting elements are typically resonate in a phase shift between them, and in some specific embodiments the flow restricting elements resonate in an antiphase manner, namely that when one is in a flow restricting state the other is in a flow permitting state and vice versa. Reference is specifically made to FIGS. 1B-1C, which exemplify the antiphase operation of the two flow restricting elements. FIG. 1B shows the driver in the first state 30o, the inlet flow restricting element 40 is in the flow permitting state range defined by any state at the range between the second end state 40i and the transition state 43 and the outlet flow restricting element 60 is in the flow restricting state defined by any state at the range between the second end state 60i and the transition state 63. FIG. 1C shows the driver in the second state 30i, the inlet flow restricting element 40 is in the flow restricting state defined by any state at the range between the first end state 40o and the transition state 43 and the outlet flow restricting element 60 is in the flow permitting state defined by any state at the range between the first end state 60o and the transition state 60.

[0073] The pump 100 operates continuously and the states of the flow restricting elements continue to switch in relation to the resonating characteristic frequency profile. In other words, in every time period of a resonance cycle of the driver, each of the flow restricting elements switches between the first and the second state one time and spends half of the time period in each state.

[0074] The flow restricting elements harmonically resonate around the resting position and in a first rotational direction from the resting position they enter a flow restricting state and in a second rotational direction from the resting position they enter a flow permitting state. The harmonic forces acting on the flow restricting elements, both intrinsic and external forces, resulting in that the strongest forces act at the end of the range of the harmonic oscillation for each state, therefore allowing a very fast transitions between states by using the harmonic resonance effect. In some embodiments, the frequency of said driver and/or a resonance frequency of a valve may range between 1 to 20 Hz and/or between 20 to 100 Hz and/or between 100 to 1000 Hz and/or between 1000 Hz to 10000 Hz and/or between 10000 Hz to 25000 Hz and/or between 25000 Hz to 200000 Hz. For example, the frequency of said driver and/or a resonance frequency of a valve may range in an audible frequency between 20 Hz to 20 kHz and/or a range out of the audible frequency for example between 25000 Hz to 250000 Hz.

[0075] Reference is now made to FIG. 2, which is a schematic illustration of a longitudinal cross section of an example showing different states of the flow restricting element. The flow restricting element 60 is in the form of a continuously oscillating flap, which is continuously transitioning between a flow permitting range of states, exemplified by the first end state 60o that is diverted from the transition state towards a first side, and a flow restricting state, exemplified by the second end state 60i that is diverted from the transition state towards a second side, opposite the first side. The state of the flow restricting element is defined by its relationship with the geometrical profile of the wall portion 65 that results in the desired gap 67 between the wall and the flow restricting element 60, being a relatively large gap in a flow permitting state and relatively narrow gap in a flow restricting state. FIG. 3 specifically exemplifies a longitudinal cross section of a flow restricting element 40/60 being shaped in a tapered manner. Alternatively or additionally, a flap may have a constant thickness. Alternatively or additionally, one portion of the flap by have a constant thickness while another portion is tapered. For example, between 0 to 10% and/or between 10 to 30% and/or between 30 to 60% and/or between 60 to 90% and/or between 90 to 100% of the flap may be tapered. Alternatively or additionally, the tapering may be near the fixed end and/or near the free end and/or both (for example, a middle portion of the flap may have uniform thickness).

[0076] To improve reproducibility of flap resonant frequency, mass, length or stiffness of the flaps are calibrated to match the resonance frequency of the driver.

[0077] Means for adjusting the resonance frequency of the flaps such as applying electromagnetic field to the flaps in the field, a flap holder adjustable by a screw or real time varying flap temperature by an individual microheating element are in the scope of the present invention. The resonant frequency can be also adjusted by piezoelectric drivers. Adjustment efficiency can be estimated according output flow and pressure monitoring data. Piezo drivers may also be used for this purpose.

[0078] Reference is now made to FIGS. 4 and 5, showing in a non-limiting manner an embodiment of a non-contact check valve 200 comprising a cylinder 210 and a valve flap in the form of a piston 220 (end positions are referred as 220i and 220o). Analogously with the valve configuration exemplified in FIGS. 1A-1C, a gap between cylinder 210 and piston 220 is sufficiently narrow for blocking of the passage and sufficiently wide for contact-free resonant oscillation of the piston 220. A biasing element 240 optionally includes an elastic element such as a spring. The biasing element 240 connects between the mobile piston and an immobile portion 250 of the pump body. Optionally, the piston sequentially moves between the flow permitting state 220o where it is not blocking flow through the cylinder 210 and the flow restricting state 220i where it restricts flow through the cylinder 210. In some embodiments the piston moves in response to changes in fluid pressure. Alternatively or additionally, movement is driven by resonant oscillation and/or active forcing.

[0079] In some embodiments, a flow direction of the pump can be switched by changing the phase relationship between driver and a valve movement and/or between the pressure phase in the pump chambers and valve movement. The aforesaid switch can be achieved by means of a slight change in a frequency of a driver (for example a membrane) which results in phase trailing or leading each valve relative to the membrane and/or a change in the flow direction.

[0080] Reference is now made to FIG. 6, presenting a one-way valve illustrated by a portion of a valve chamber wall 310 provided with an opening 320. A valve flap 330 can displace (vibrate) in a direction 350 parallel to a portion of wall 310. The flap has an opening 340, which is biased to a normal position which is displaced relative to the opening 320. In other words, in normal position, the valve is closed. When pressure in the pump chamber increases, the flap 330 is displaced up and coincides with the opening 340. This up position of the flap 330 allows the pressurized fluid (e.g. liquid or gas) accommodated within the valve chamber to be blown off.

[0081] For purposes of the present invention, the term “proximal end” 333 of the flap member refers to a flap member portion in proximity to a member holder (not shown) while the term “distal end” 335 refers to an opposite portion provided with an opening. Specifically, proximal and distal portions are marked as 333 and 335, respectfully.

[0082] In some embodiments, flap 330 may be tuned. For example, when the valve is being used in a device having a characteristic stroke frequency, flap 330 may be tuned to resonate at the characteristic frequency.

[0083] Reference is now made to FIG. 7, presenting a two-way valve. According to this embodiment of the present invention, the valve chamber wall 310 is provided with two openings 323 and 325 which are in a fluid connection with pipes 327 and 329, respectively.

[0084] A vibrating valve flow 330 blocks alternatively the top opening 325 in response to changes in pressure inside the valve chamber. In this position, the air accommodated in the valve chamber is discharged through the lower opening 323 and pipe 327. The aforesaid opening 323 is blocked when the air pressure inside the valve chamber is low. At the same time, outer air enters the valve chamber through the top opening 325 and pipe 329.

[0085] In some embodiments, flap 330 may be tuned. For example, when the valve is being used in a device having a characteristic stroke frequency, flap 330 may be tuned to resonate at the characteristic frequency.

[0086] It should be emphasized that according to the present invention, the flap is narrow, so fluid (e.g. liquid or gas in the chamber) can freely flow around the flap as needed.

[0087] It should be emphasized that in the claimed micro-pump there is any mechanical contact between the oscillating flaps 40 and 60 and the non-movable part 45 and 65, respectively. The proposed technical solution prevents the oscillating flaps 40 and 60 from wear that occurs in the known standard flap valves. Moreover, during operation, mechanical contact between the valve flap and seat the results in substantial losses, specifically, in generation of substantial level of heat and noise. In the claimed micro-pump, energy losses are minimized.

[0088] In accordance with one embodiment of the current invention, a resonant membrane micro-pump 100 for providing fluid pressure is disclosed. The aforesaid pump 100 comprises: (a) a pump chamber 20; (b) a resonantly driven membrane 30, the membrane is configured to modulate a pressure of a fluid accommodated in the pump chamber 20; (c) an inlet check valve 110 adapted for inflowing the fluid into the chamber 20; (d) an outlet check valve 120 adapted for outflowing the fluid from the chamber 20. Each valve comprises a passage 42/62 adapted for conducting a fluid flow and a blocking element adapted for intermittently blocking the fluid flow.

[0089] In some embodiments, the blocking elements of the valves 110 and 120 having a geometric shape and a mass distribution thereof matched with resonant coherent oscillation in said passages 42 and 62, respectively, when excited by the membrane 30 such that the blocking elements block the fluid flow in an antiphase manner.

[0090] In accordance with another embodiment of the current invention, the membrane 30 and the flaps 40 and 60 are configured for resonant oscillation out of audible frequencies.

[0091] In accordance with a further embodiment of the current invention, the blocking element is a resonantly oscillating flap 40/60.

[0092] In accordance with a further embodiment of the current invention, the flap 40/60 is configured for partially blocking the passage 42/62 with a gap 47/67 between the fixed member 45/65 and the flap 40/60 being sufficiently narrow for blocking of the passage 42/62 and generating a fluid outflow. The gap 47/67 provides sufficient clearance for contact-free resonant oscillation of said flap 40/60.

[0093] In accordance with a further embodiment of the current invention, the flap is of a tapered shape.

[0094] In accordance with a further embodiment of the current invention, the blocking element is a resonantly oscillating piston 220 connected to an abutment 250 by means of a spring 240.

[0095] In accordance with a further embodiment of the current invention, a method of providing fluid pressure is disclosed. The aforesaid method comprises the steps of: (a) providing a resonance membrane micro-pump 100 for providing fluid pressure; the aforesaid pump 100 comprising (i) a pump chamber 20; (ii) a harmonically driven membrane 30, the membrane is configured to modulate a pressure of a fluid accommodated in the pump chamber 20; (iii) an inlet check valve 110 adapted for inflowing said fluid into the chamber 20; (iv) an outlet check valve 120 adapted for outflowing the fluid from the chamber 20; each valve comprises: a passage 42/62 adapted for conducting a fluid flow and a blocking element adapted for intermittently blocking said fluid flow; the blocking elements of the valves 110 and 120 have a geometric shape and a mass distribution thereof such that said blocking elements are matched with resonant coherent oscillation in said passages 42 and 62, respectively, when excited by said membrane 30 such that said blocking elements block said fluid flow in an antiphase manner.

[0096] In some embodiments, the step of blocking the fluid flow performed by resonantly oscillating blocking elements 40 and 60 in the passages 42 and 62, respectively, when excited by the membrane 30.

[0097] In accordance with a further embodiment of the current invention, the membrane 30 and the flaps 40 and 60 resonantly oscillate at a frequency out of audible frequencies.

[0098] In accordance with a further embodiment of the current invention, the step of blocking the passage 42/62 is performed by resonantly oscillating flaps 40 and 60.

[0099] In accordance with a further embodiment of the current invention, the passage 42/62 is partially blocked by the flap 40/60, so that a gap 47/67 between the fixed member 45/65 and the flap 40/60 is sufficiently narrow for blocking of the passage 42/62 and generating a fluid outflow. The gap 47/67 provides sufficient clearance for contact-free resonant oscillation of said flap 40/60.

[0100] In accordance with a further embodiment of the current invention, the step of blocking the passage 42/62 is performed by said flap 40/60 of a tapered shape.

[0101] In accordance with a further embodiment of the current invention, the step of blocking said passage 42/62 is performed by a resonantly oscillating piston 220 connected to an abutment 250 by means of a spring 240.

[0102] In some embodiments, a valve of the present invention is formed using micro techniques, for example like an integrated circuit and/or an electronic chip. For example, a valve may be fabricated by a photolithography, deposition (such as chemical vapor deposition), and/or etching. The main process steps are optionally supplemented by doping and etching, ion beam milling etc.

[0103] FIG. 8 is a block diagram of a valve in accordance with an embodiment of the current invention. In some embodiments, a valve includes an opening 882 and a flap 884. For example, the flap 884 may have a closed position where it blocks (and/or partially blocks) flow through the opening and/or an open position where fluid is allowed to flow relatively freely through the opening. Optionally the flap oscillates between the open and closed positions either as a result of changes in fluid pressure and/or under driving of an active mechanism. Optionally, the flap 882 resonance frequency. For example, the resonance frequency may be adjusted to correspond to a driving frequency of flow.

[0104] FIG. 9 is a flow chart illustration of a method of controlling fluid flow in accordance with an embodiment of the current invention. In some embodiments, flow is driven 992 as a characteristic frequency. Optionally a valve oscillates between an open state and a closed state (for example fully closed and/or partially closed). Optionally the valve is tuned such that oscillation of the valve between the open and closed state has resonance frequency matching the characteristic driving frequency. For example, the valve may resonate 994 at the characteristic driving 992 frequency.