CN117109678A - Micro valve and mass flowmeter applied to same - Google Patents
Micro valve and mass flowmeter applied to same Download PDFInfo
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- CN117109678A CN117109678A CN202310721559.2A CN202310721559A CN117109678A CN 117109678 A CN117109678 A CN 117109678A CN 202310721559 A CN202310721559 A CN 202310721559A CN 117109678 A CN117109678 A CN 117109678A
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- cantilever
- throttle
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/005—Valves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
Abstract
The invention relates to the technical field of micro-valves, and provides a micro-valve and a mass flowmeter applied to the micro-valve. The microvalve includes a first substrate, a second substrate, and an intermediate layer, wherein the intermediate layer is disposed between the first substrate and the second substrate, the intermediate layer comprising: an array of a plurality of actuators, the performing comprising: an orifice having a throttle inlet and a throttle outlet, gas flowing from the throttle inlet into the orifice and from the throttle outlet to the second substrate; and a cantilever that moves relative to the throttle inlet, wherein an opening area of the throttle inlet is adjusted by adjusting a distance between the cantilever and the throttle inlet. According to the invention, the opening area of the throttle air inlet is adjusted by moving the cantilever relative to the throttle air inlet so as to improve the valve flux. The actuator array may enable proportional control and may enable diffuse gas or form a mass flow meter. In addition, a plurality of micro-valves can be mutually spliced to further improve the flow.
Description
Technical Field
The present invention relates generally to the field of microvalve technology. In particular, the invention relates to a micro valve and a mass flowmeter for use therewith.
Background
The structure of a conventional Micro Valve (Micro Valve) or microelectromechanical system Valve (mems Valve) is similar to that of a Diaphragm Valve (Diaphragm/Membrane Valve). Figures 1A-B show schematic diagrams of prior art micro-valves. As shown in fig. 1A-B, an actuatable diaphragm is provided on top of the micro valve, a valve seat is provided below the diaphragm, and an Actuator (or the diaphragm is also an Actuator) pushes the diaphragm upward to open the aperture (Orifice) or downward to close the aperture. Wherein the magnitude of the flux of the microvalve is determined by the perimeter of the aperture x the stroke (Displacement) of the diaphragm.
Conventional micro-valves are typically constructed with a bottom substrate (silicon or quartz glass) as the base, channels etched in the substrate for horizontal flow of gas or liquid, and a diaphragm and/or actuator bonded to the channels to form the complete micro-valve. For the case that the flow channel is complicated or deep etching is needed, channels can be respectively manufactured on two substrates, and the two substrates are aligned and then bonded together to form a complete flow channel.
Due to the micro-scale or even nano-scale processing characteristics of the MEMS process, the thickness of the substrate used for processing is usually only 625um, the deposition thickness of lead zirconate titanate (PZT) is usually only 5um at maximum, the depth and aperture of deep trench etching are not more than 1mm, the upward movement stroke of the diaphragm is usually in the micrometer scale (for example, the upward movement stroke of a 25mm PZT ceramic cantilever is usually only 250um, and only 10 um-scale movement can be usually realized on the micro-nano structure of the MEMS). In other words, conventional micro-valves can only achieve micro-liter level flow control. Taking a 1/8 inch opening as an example, an opening of 1.78mm diameter would produce only 1.78 x 0.01 x 3.14= 0.055892mm for a diaphragm with a mating stroke of 10um 2 Even if the stroke of the diaphragm can reach 100um, only 0.56mm can be produced 2 Is a flux of (a). In the prior art, the 1/8 inch opening and the diaphragm with the 100um stroke still have certain realization air spaces, and the stroke of the diaphragm in the micro valve is only about 10-20 um.
Therefore, there is a need to propose a new type of micro-valve that can achieve a larger valve flux.
Disclosure of Invention
To at least partially solve the above-mentioned problems in the prior art, the present invention proposes a micro valve comprising:
a first substrate having a substrate inlet, wherein gas flows from the substrate inlet to an intermediate layer;
an intermediate layer disposed between the first substrate and the second substrate, the intermediate layer comprising an array formed by a plurality of actuators comprising:
an orifice having a throttle inlet port and a throttle outlet port, wherein gas flows from the throttle inlet port into the orifice and from the throttle outlet port to the second substrate; and
a cantilever configured to move relative to the throttle inlet, wherein an opening area of the throttle inlet is adjusted by adjusting a distance between the cantilever and the throttle inlet; and
A second substrate having a substrate exit port, wherein gas flows from the substrate exit port.
In one embodiment of the invention, it is provided that the micro valve further comprises:
the shell surrounds the actuator and is a gas constraint space or shell, the gas inlet constraint space shell is provided with a shell gas inlet and a shell gas outlet, and the shell comprises a metal shell, a ceramic shell or a resin shell or a constraint space formed by a comparable semiconductor packaging process.
In one embodiment of the invention, the orifice includes:
an orifice step connected to the second substrate, wherein the orifice vent is disposed on the orifice step; and
an orifice fence, a first end of which is connected with the first substrate, and a second end of which is opposite to the first end is connected with the orifice step, the orifice intake port being arranged on the orifice fence.
In one embodiment of the invention, it is provided that the first substrate further comprises:
a substrate step connected to a first end of the orifice enclosure, wherein the substrate step and/or the orifice step are configured to inhibit a short circuit airflow created by a gap between the cantilever and the second substrate and/or the first substrate.
In one embodiment of the invention, it is provided that the cantilever has a coating of wetting material thereon; and/or
The cantilever comprises an electrostatic driving cantilever, an electromagnetic driving cantilever, a piezoelectric driving cantilever or an electrothermal driving cantilever.
In one embodiment of the invention, it is provided that the cantilever is configured for horizontal movement relative to the throttle inlet; or alternatively
The cantilever is configured to move vertically relative to the throttle inlet.
In one embodiment of the invention, provision is made for further comprising:
and an outer frame disposed around the intermediate layer to restrict an air flow.
In one embodiment of the invention, it is provided that the orifice enclosure comprises a first orifice and a second orifice opposite the first orifice; and
the boom includes a first boom configured to move relative to the first throttle inlet and a second boom configured to move relative to the second throttle inlet.
In one embodiment of the invention, it is provided that a grating is provided on one or more of the following to form the laminar element: a substrate air inlet, a substrate air outlet, and a throttle air outlet.
In one embodiment of the invention, it is provided that the cantilever is connected to one or more orifices.
In one embodiment of the invention, it is provided that a plurality of micro-valves are configured to splice with each other to increase flow.
In one embodiment of the invention, it is provided that the orifice outlets of the plurality of actuators are vented individually or in groups to achieve diffuse venting.
In one embodiment of the invention, it is provided that the micro valve further comprises:
and a control circuit connected to the plurality of actuators, the control circuit being configured to control the opening degrees of the plurality of actuators, respectively.
The term "opening" herein refers to the proportion of actuator opening, which may be any value between 0 and 100%.
In one embodiment of the invention, it is provided that the control circuit is configured to perform the following actions:
setting the flow to be controlled as Q setpoint ；
Determining the maximum exact measurement value of a single actuator as max (Q actr )；
Calculating i=rounding { Q setpoint /max(Q actr )}；
Opening i actuators, wherein the sum of the flows of the i actuators is i×max (Q actr ) The method comprises the steps of carrying out a first treatment on the surface of the And
opening the (i+1) th actuator, and setting the flow rate of the (i+1) th actuator to Q setpoint -i×max(Q actr )。
In an embodiment of the invention, it is provided that the control circuit is further configured to perform the following actions:
when the flow rate of the i+1th actuator is below the threshold, the flow rate of the i-j, i-j+1, & i, i+1 total j+2 actuators is set to (Q setpoint -j×max(Q actr ))/(j+2)。
The present invention also proposes another micro valve comprising:
a first substrate having a substrate inlet, wherein gas flows from the substrate inlet to an intermediate layer;
an intermediate layer disposed between the first substrate and the second substrate, the intermediate layer comprising an array formed by a plurality of actuators comprising:
an orifice having a throttle inlet port and a throttle outlet port, wherein gas flows from the throttle inlet port into the orifice and from the throttle outlet port to the second substrate; and
a diaphragm configured to control an opening degree of the throttle inlet; and
a second substrate having a substrate exit port, wherein gas flows from the substrate exit port.
In one embodiment of the invention, it is provided that the first substrate is configured to restrict the gas flow and the second substrate has a substrate gas inlet and a substrate gas outlet, wherein gas flows from the substrate gas inlet to the intermediate layer and flows back to the second substrate before flowing out of the substrate gas outlet.
The invention also proposes a mass flowmeter comprising:
and (3) micro-valve: and
a sensing component disposed on at least one of the plurality of actuators of the micro valve.
In one embodiment of the invention, it is provided that the sensor element comprises a pressure sensor and a temperature sensor, wherein the micro valve, the pressure sensor and the temperature sensor form a pressure-type mass flowmeter; and/or
The sensing component includes a heater and a temperature sensor, wherein the micro valve, the heater and the temperature sensor form a thermal mass flow meter.
In one embodiment of the invention, it is provided that for blocking flow, the flow Q through the ith actuator on the microvalve is regulated according to the following formula i ：
Q i ＝C×P UPi ，
Wherein C represents a first correlation coefficient, P UPi Representing the pressure on the first side of the i-th actuator, wherein the first correlation coefficient C is related to the opening area A of the i-th actuator i Positive correlation; and/or
For non-blocking flow, flow through the ith actuator on the micro valve is adjusted according to the following formula
Wherein C' represents a second correlation coefficient, A i Represents the opening area, P, of the ith actuator DOWNi The pressure on the second side of the ith actuator, R, T, M, γ, and the specific heat ratio, where the second phase relationship C' is a constant.
The invention has at least the following beneficial effects: the invention provides a micro valve, which comprises an array formed by a plurality of actuators, wherein a cantilever in each actuator can move relative to a throttling air inlet to adjust the opening area of the throttling air inlet, so that the valve flux can be effectively improved. The plurality of actuators may form an actuator array that may achieve proportional control and may achieve diffuse gas or form a mass flow meter. In addition, a plurality of micro-valves can be mutually spliced to further improve the flow.
Drawings
To further clarify the advantages and features present in various embodiments of the present invention, a more particular description of various embodiments of the present invention will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. In the drawings, for clarity, the same or corresponding parts will be designated by the same or similar reference numerals.
Figures 1A-B show schematic diagrams of prior art micro-valves.
Figure 2 illustrates a perspective view of a micro valve and its packaging housing in one embodiment of the invention.
Figure 3 shows a schematic diagram of a micro valve in one embodiment of the invention.
Figure 4 shows a perspective schematic view of a micro valve in one embodiment of the invention.
Figure 5 illustrates a top view of a micro valve in one embodiment of the invention.
Figure 6 illustrates a split schematic of a microvalve in one embodiment of the present invention.
Fig. 7A shows a schematic bottom view of a first substrate in one embodiment of the invention.
FIG. 7B shows a schematic diagram of a second substrate and orifice in an embodiment of the invention.
Fig. 8A and 8B show top views of an intermediate layer when an actuator is opened and closed, respectively, in accordance with one embodiment of the present invention.
Fig. 9 shows a schematic diagram of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention.
Fig. 10 shows a top view of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention.
Fig. 11 shows a split schematic of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention.
Fig. 12 shows a schematic bottom view of a first substrate in another embodiment of the invention.
Fig. 13 shows a schematic diagram of a second substrate and orifice of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention.
Fig. 14 shows a schematic diagram of a cantilever-actuated micro valve in accordance with one embodiment of the present invention.
Fig. 15A and 15B are schematic diagrams illustrating an intermediate layer of a cantilever-actuated micro valve in accordance with an embodiment of the present invention.
FIGS. 16A and 16B illustrate a schematic flow diagram of a cantilever-actuated micro valve in accordance with one embodiment of the present invention.
Fig. 17 shows a schematic diagram of the arrangement of sensors on a micro valve in one embodiment of the invention.
Fig. 18 shows a schematic diagram of a conventional thermal mass flowmeter.
Fig. 19 shows a schematic diagram of an actuator structure on one die in one embodiment of the invention.
Figure 20A shows a schematic view of a grid under one cantilever in one embodiment of the invention.
Figure 20B shows a side view of the grid under one cantilever in one embodiment of the invention.
FIG. 21 illustrates a control logic schematic of an actuator array in accordance with one embodiment of the invention.
Fig. 22 shows a schematic diagram of a micro valve in another embodiment of the invention.
FIG. 23 illustrates a schematic diagram of the airflow at an actuator in one embodiment of the invention.
FIG. 24 is a schematic diagram showing the pressure versus flow rate of a choked flow in an embodiment of the invention.
Detailed Description
It should be noted that the components in the figures may be shown exaggerated for illustrative purposes and are not necessarily to scale. In the drawings, identical or functionally identical components are provided with the same reference numerals.
In the present invention, unless specifically indicated otherwise, "disposed on …", "disposed over …" and "disposed over …" do not preclude the presence of an intermediate therebetween. Furthermore, "disposed on or above" … merely indicates the relative positional relationship between the two components, but may also be converted to "disposed under or below" …, and vice versa, under certain circumstances, such as after reversing the product direction.
In the present application, the embodiments are merely intended to illustrate the scheme of the present application, and should not be construed as limiting.
In the present application, the adjectives "a" and "an" do not exclude a scenario of a plurality of elements, unless specifically indicated.
It should also be noted herein that in embodiments of the present application, only a portion of the components or assemblies may be shown for clarity and simplicity, but those of ordinary skill in the art will appreciate that the components or assemblies may be added as needed for a particular scenario under the teachings of the present application. In addition, features of different embodiments of the application may be combined with each other, unless otherwise specified. For example, a feature of the second embodiment may be substituted for a corresponding feature of the first embodiment, or may have the same or similar function, and the resulting embodiment may fall within the scope of disclosure or description of the application.
It should also be noted herein that, within the scope of the present application, the terms "identical", "equal" and the like do not mean that the two values are absolutely equal, but rather allow for some reasonable error, that is, the terms also encompass "substantially identical", "substantially equal". By analogy, in the present application, the term "perpendicular", "parallel" and the like in the table direction also covers the meaning of "substantially perpendicular", "substantially parallel".
The numbers of the steps of the respective methods of the present invention are not limited to the order of execution of the steps of the methods. The method steps may be performed in a different order unless otherwise indicated.
The invention is further elucidated below in connection with the embodiments with reference to the drawings.
Figure 2 illustrates a perspective view of a micro valve and its packaging housing in one embodiment of the invention. As shown in fig. 2, in which the micro-valve is encapsulated inside the housing 201, gas can flow in or out through the vent holes on the housing 201, and the housing 201 can use a common metal, ceramic or resin encapsulation process. The micro-valve may include a plurality of actuators, which may include a first substrate 202, a second substrate 203, and an intermediate layer 204. The middle layer 204 is disposed between the first substrate 202 and the second substrate 203, and the first substrate 202 and the second substrate 203 are provided with an air inlet hole and/or an air outlet hole, wherein the air can flow in from the first substrate 202 or the second substrate 203, flow through the middle layer 204 and flow out from the second substrate 203 or the opposite side of the first substrate 202, or flow in from the first substrate 202 or the second substrate 203, flow through the middle layer 204 and flow out from the same side of the first substrate 202 or the second substrate 203.
The intermediate layer 204 is provided with openings (Orifice) and horizontally arranged cantilevers (Cantilever), which are also diaphragms in micro-valves, wherein the cantilevers may be provided with a coating of a wetting material to protect the cantilevers. An outer frame may be provided around the middle layer 204 to restrict the air flow. In the intermediate layer 204, the cantilever may move relative to the aperture to adjust the distance between the cantilever and the aperture, thereby changing the aperture opening/flux of the aperture to achieve proportional adjustment of the micro valve. A step may be provided at the location of the opening near the first substrate 202 and the second substrate 203, which step may reduce or even eliminate the short-circuit air flow created by the gap between the cantilever and the first substrate 202 and the second substrate 203. The cantilever may be an electrostatically, electromagnetically, piezoelectrically or electroheat driven cantilever.
It should also be understood that in fig. 2 and other figures of the description, the curvature of the cantilever is shown exaggerated to illustrate the principle, which may not be proportional to the actual situation.
Figure 3 shows a schematic diagram of a micro valve in one embodiment of the invention. As shown in fig. 3, the structure of the micro valve is shown with the package housing removed, and the outer frame disposed around the middle layer 204 is hidden. It can be seen that the first substrate 202 processed by the MEMS process is provided with a plurality of air holes 301 and the intermediate layer 204 is provided with a cantilever 302.
Figure 4 shows a perspective schematic view of a micro valve in one embodiment of the invention. Figure 5 illustrates a top view of a micro valve in one embodiment of the invention. As shown in fig. 4 and 5, the intermediate layer 204 includes a plurality of actuators including a cantilever 302 and an orifice 401, wherein the orifice 401 includes an orifice gas outlet 4011 and a baffle 4012 disposed around the orifice gas outlet 4011.
The micro-valve in the present invention may be a matrix array formed by a plurality of small micro-valves (actuators). The micro-valve of the present invention may include n×m outlets on the outer frame, each outlet corresponding to i (i=1 or 2) orifices 401, respectively, so the micro-valve may be regarded as an array of m×n×i actuators. In the packaging process, if n×m outlets on the outer frame are not converged or are converged to x×f outlets (x < m, y < n), the micro valve can uniformly give out air on a plane.
In the present invention, the micro-valve typically packages a Die (Die) on a Wafer (Wafer) in a Package. The encapsulated package element may be attached to a vacuum bonded radial seal (VCR, vacuum Coupling Radius Seal) fitting or may be arranged on the pipe module by Surface Mount (Surface Mount). Since the Die (Die) Size is limited by the exposure area (Short Size) of the lithography machine, multiple dies, each with an array of multiple actuators built into it, can also be packaged in a single package element in order to increase the flow of the micro-valve. Wherein the actuator arms 302 may be single point fixed or two point fixed, each arm 302 corresponding to one or more orifices 401. A grating may be provided within the orifice 401 to reduce the reynolds number of the orifice 401, thereby allowing the orifice 401 to form a laminar flow element.
Figure 6 illustrates a split schematic of a microvalve in one embodiment of the present invention. As shown in fig. 6, in which the intermediate layer 204 includes a plurality of actuators including an orifice 401 and a cantilever 302, the first substrate 202 and the second substrate 203 are provided with an air hole 301, and the first substrate 202, the intermediate layer 204, and the second substrate 203 are bonded together to form a micro valve.
Fig. 7A shows a schematic bottom view of a first substrate in one embodiment of the invention. FIG. 7B shows a schematic diagram of a second substrate and orifice in an embodiment of the invention. As shown in fig. 7A and 7B, a first step 701 may be provided on the first substrate 202, and a second step 702 may be provided on the second substrate 203. During the movement of the cantilever 302, due to the gap between the cantilever 302 and the first substrate 202 and the second substrate 203, there is also a gap between the cantilever 302 and the orifice 401, and the step may be higher than the gap of the cantilever 302, thereby sealing the gap between the cantilever 302 and the orifice 401. The first substrate 202 and the second substrate 203 may be quartz substrates, silicon substrates, SOI substrates, or silicon carbide substrates. Since the cantilever 302 may have sagging, the step disposed below the orifice 401 may be shallower than the step disposed above the orifice 401. In addition, the step needs to have a height so that the air flow can flow into the orifice 401 along the upper or lower edge of the step to increase the flux.
Fig. 8A and 8B show top views of an intermediate layer when an actuator is opened and closed, respectively, in accordance with one embodiment of the present invention. As shown in fig. 8A and 8B, the proportional control of the flux can be achieved by controlling the distance between the cantilever 302 and the orifice 401 during the movement of the cantilever 302. Where flux (open area) =perimeter of orifice 401×distance between cantilever 302 and orifice 401, gas can flow through orifice 401 and then through the 90 degree fold line down through vent 301 on second substrate 203. In order to maximize the flow rate of the micro valve, it is necessary that the maximum opening area of each orifice 401 is equal to or smaller than the area of the corresponding air outlet vent 301, and the sum of the maximum opening areas of all the orifices 401 is smaller than the sum of the areas of all the air inlet vents 301.
Fig. 9 shows a schematic diagram of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention. Fig. 10 shows a top view of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention. As shown in fig. 9 and 10, the orifice 401 of the actuator is provided with a two-way opening, and a first cantilever 901 and a second cantilever 902 are provided at both openings, respectively. In this embodiment, the orifice 401 may be formed by front and rear vertical baffles and up and down steps, and the flux of the orifice 401 is the sum of the fluxes of the two openings, wherein the sum of the fluxes of the two-way openings is equal to or less than the sum of the fluxes of the corresponding air outlet vents 301. The symmetry of the double-cantilever double-opening micro valve is better, and the integrated processing of the MEMS technology is more facilitated.
Fig. 11 shows a split schematic of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention. Fig. 12 shows a schematic bottom view of a first substrate in another embodiment of the invention. As shown in fig. 12, the bottom of the first substrate 202 of the double cantilever double opening micro valve may also be provided with a first step 701 for shielding the gap between the first cantilever 901 and the second cantilever 902 at the orifice 401 and the first substrate 202.
Fig. 13 shows a schematic diagram of a second substrate and orifice of a dual cantilever dual opening micro valve in accordance with another embodiment of the present invention. As shown in fig. 13, in which the orifice 401 is arranged on the second substrate 203, and a second step 702 is provided between the orifice 401 and the second substrate 203.
In this embodiment, the micro-valve process may include:
the second substrate 203 and the orifice 401 are structured by an etching process on the oxide layer of the SOI wafer.
A first cantilever 901 and a second cantilever 902 are formed on the oxide layer of the other S01 wafer, wherein the PZT layer or the electrostatic actuation layer on the bimorph can be double-sided processed. The processing method of the actuation layer may include Chemical Vapor Deposition (CVD), reactive Physical Vapor Deposition (RPVD), physical Vapor Deposition (PVD), or sol-gel (SolgelJI) methods.
The first substrate 202 may be constructed on another S01 wafer.
The SOI wafer may be boron doped and thinned to 100-200um. Further, the surface of the via and the devices may be protected by CVD or other methods by applying a low dielectric constant passivation layer (e.g., a nitroxide organic polymer) to avoid corrosion of the devices and contamination of the high purity gases.
Fig. 14 shows a schematic diagram of a cantilever-actuated micro valve in accordance with one embodiment of the present invention. As shown in fig. 14, in which the cantilever can be moved up and down, the gas flows in from above or below. Fig. 15A and 15B are schematic diagrams illustrating an intermediate layer of a cantilever-actuated micro valve in accordance with an embodiment of the present invention. As shown in fig. 15A, the cantilever may be bilaterally fixed. As shown in fig. 15B, the cantilever may be single-sided stationary. Wherein the travel of the cantilever fixed on one side is greater.
FIGS. 16A and 16B illustrate a schematic flow diagram of a cantilever-actuated micro valve in accordance with one embodiment of the present invention. As shown in fig. 16A and 16B, the inlet of the gas may be on the first substrate 202 or the second substrate 203. In the embodiment shown in fig. 16A, the gas inlet and outlet are both on the second substrate 203, and the gas inlet and outlet channels are in a dog-bone shape or a finger-bone shape, and the gas inlet and outlet can be distributed and the gas outlet can be collected and combined on the second substrate 203.
The micro-valve with cantilever vertical motion can obtain about 2/3 of the filling factor in the X-axis direction, about 1/1 of the filling factor in the Y-axis direction, and about 50% of the filling factor in total. Assuming that each 75% of the length in the Y-axis direction can be given air, the width of each cantilever is 70um, the distance between the cantilevers is 30um, and the average stroke of the cantilevers is 5um (the stroke of the highest point of the cantilevers is 10um, and the lower flow passage section can be approximated as a triangle). Assuming that the length and width of the die on the wafer are 10mm, an effective size of 7.5mm can be obtained in the length direction of the die, and 100 rows of cantilevers are provided. The total flux area of the cantilever-actuated microvalve may be 7.5mm by 0.005 by 100 by 2=7.5 mm 2 . That is to say that the flux area of a 2cm x 1cm die can be comparable to a 1/4 inch pipe,the flux area of a 2cm by 3cm die may be comparable to a 3/4 inch pipe. And the micro valve can bear larger pressure drop and flow velocity compared with the pipeline, thus 1cm 2 Or 2cm 2 The MEMS process area of the valve can meet the application requirements of a proportional control valve (MFC) in the current semiconductor equipment.
Fig. 17 shows a schematic diagram of the arrangement of sensors on a micro valve in one embodiment of the invention. Wherein pressure sensors may be arranged at the air inlet and the air outlet and temperature sensors may be arranged to form a pressure type mass flow meter. A heater and a thermometer may be provided on the orifice 401 to form a thermal mass flow meter, and this orifice 401 may be equivalent to a heat flow measurement passage in the thermal mass flow meter. Fig. 18 shows a schematic diagram of a conventional thermal mass flowmeter. As shown in fig. 18, where the measurements are made in the bypass channel. While in the embodiment of the invention shown in fig. 17, the heater and temperature and may be placed upstream of or in an orifice 401, this orifice 401 corresponds to the measurement bypass in fig. 18. A grill may be etched at the orifice 401, air inlet, air outlet to form a laminar flow member. Indeed, in embodiments of the present invention, because the size of the orifice 401 is small enough, the orifice 401 and the flow path between the first and second substrates 202, 203 may form a natural laminar flow element. Figure 20A shows a schematic view of a grid under one cantilever in one embodiment of the invention. Figure 20B shows a side view of the grid under one cantilever in one embodiment of the invention. As shown in fig. 20A-B, the grid below the cantilever arm may reduce the characteristic dimensions of the conduit, reduce the reynolds number, form a laminar element (LFE), and may be added to form a laminar element in other intake circuits, as described above.
In embodiments of the present invention, multiple dies may be consolidated and packaged to achieve both flow expansion and diffuse outgassing. Fig. 19 shows a schematic diagram of an actuator structure on one die in one embodiment of the invention. As shown in fig. 19, there may be a 4×2 actuator structure on one die, four orifices 401 on each actuator, two-way openings on the orifices 401, and cantilevers at the two openings, respectively. The cantilever length is assumed to be 2mm and the spacing between the cantilevers is 100um. Then a 20 x 10mm highland can be configured with a 10 x 100 array of actuators, and very precise flow control can be achieved if each actuator is controlled. In fig. 19, 4 2 x 2 die packages can be combined into a larger mass flow meter, i.e., flow x 4. The air outlets of each orifice are not combined (or are combined into a plurality of groups), and each air outlet (or each group of air outlets) independently air out, so that independent and uniform diffuse air out of the mass flowmeter can be realized.
The area flux of the actuator depends on min (a inlet ，A orifice ，A outlet ) Wherein A is inlet Indicating the area of the air inlet of the actuator, A outlet Indicating the area of the air outlet of the actuator, A orifice Indicating the area of the orifice. The total flux of the actuator array is determined by the area flux of the plurality of actuators. Due to A inlet 、A orifice 、A outlet Is proportional to each other, and thus can be obtained by determining A inlet 、A orifice 、A outlet Total area A of MEMS process total The ratio between them, i.e. the Fill-in Factor. That is to say when a for the die of the MEMS process total When the ratio between the characteristic dimensions and the ratio between the characteristic dimensions is determined, the A of the actuator can be determined inlet 、A orifice A is a outlet In turn, the flux area of the actuator array may be determined. When the flow rate, temperature, pressure are determined, the flow rate of the actuator array may be determined.
The calculation is performed by taking the air inlet and the air outlet of the actuator as rectangles, and factor=3.14/4 can be set in consideration of the round angles on the air inlet and the air outlet.
A inlet ＝W inlet ×L inlet ，A outlet ＝W outlet ×L outlet ，A total ＝W×L，
Wherein L is inlet 、W inlet Indicating the length and width of an air inlet of the actuator, L outlet 、W outlet Representing the length and width of the air outlet of the actuator, L, W representing the length and width of the die.
For a single cantilever single opening actuator, A orifice ＝2×(L open +H open )×Δ open For a double cantilever double opening actuator, A orifice ＝4×(L open +H open )×Δ open Wherein L is open 、H open Indicating the length, height, delta of the orifice opening open Indicating the distance of cantilever movement. L (L) open 、L inlet L and outlet and (5) approximating. And A is orifice Need to be equal to A inlet A is a outlet Approximately, assume H open In the case of negligible, A orifice ＝2×L open ×Δ open . Will be L outlet ＝L open Can get->Or for dual cantilever dual opening actuators
In general, the distance delta of cantilever motion open Will not be large and can be obtained by making W outlet 、W inlet About 2 or four times delta open To increase the fill factor, more precisely by further calculating H open (which is slightly less than the height of the cantilever motion). And through the calculation, in the case of matching the sizes of the throttle hole, the air inlet and the air outlet, the flux of the micro valve is limited by delta which is larger conventionally open The flux of the invention is not greatly affected.
In one embodiment of the invention, the cantilever has a height approximately 80-100um, a length approximately 200um-3mm, and a width approximately 20-50um, delta, approximately equal to the thickness of the SOI wafer open Is 1.5-22 um.delta open And under larger conditions, the processing of the throttle hole is facilitated, and the filling factor can be improved.
As described above, A after optimization inlet 、A orifice 、A outlet Is close in size, thus calculating A inlet 、A outlet Can determine A total . In the length direction of the bare chip, orthographic projections of the air inlet and the air outlet cannot be overlapped, and after the orifice enclosure is removed, the filling factor of the optimized bare chip in the length direction is about 1/3. In the width direction of the air outlet and the die, the width of the cantilever, the enclosure of the orifice, and delta open Sum, or width of two cantilevers, of two times delta open And a fill factor of 2/5 can be achieved. A further fill factor of 2/3 (e.g. chamfer) is superimposed, the total fill factor may be 1/3 x 2/5=8.9%. Thus at 30mm 2 The on-die flux area of (a) may be greater than 1/8 inch in pipeline, at 250mm 2 The size of the flux area on the die may be greater than 1/4 inch of the pipeline, and further greater flux may be achieved by stitching the die. Compared with the traditional pipeline, the micro valve provided by the invention can bear higher flow rate, the flow rate of the gas in the pipeline is 12-15m/s, if the flow rate is increased to three times, namely, the flow rate of the gas is increased to 30-45m/s,250mm 2 The on-die flux area of (c) may be greater than or equal to 3/8 inch pipes.
In the present invention, a plurality of actuators may form an actuator array. FIG. 21 illustrates a control logic schematic of an actuator array in accordance with one embodiment of the invention. As shown in fig. 21, the plurality of actuators are connected to a digital control circuit through metal vias, or bonded to a substrate provided with a control circuit that can control the opening of any of the actuators. In one embodiment of the present invention, the number of actuators that are turned on may be selected by a bond Bit Line (Bit Line) to provide more precise control of flow.
Taking an actuator array of 100 actuators as an example, the actuators may be configured such that the flow rate at which each actuator is fully open is approximately the same, i.e., a single actuator fully open may achieve a 1% increase in flow rate. Assuming that the accuracy of the proportional opening degree of the individual actuators themselves is 5%, the actuator array can obtain a control accuracy of 0.05%.
In addition, the actuators in the actuator array can be configured in a time-redundancy manner, so that the service life can be prolonged. In one embodiment of the invention, 120 actuators are provided, each having a plurality of orifices and air outlets. Wherein each air outlet has an independent bit line for selecting its operating state. Wherein the total flux of the actuator array is calibrated to 100 actuators, the flux of the actuator array is 120% of the nameplate value. When one actuator fails, a new backup actuator can be connected through a circuit, so that the valve array can continuously obtain enough flux, and the service life of equipment is effectively prolonged. In addition, the total switching times and the total travel of each actuator can be recorded through firmware. The service life of the actuator is related to the switching times, and the recording of the switching times of the valve is a method for judging the service life loss. Or the travel (distance) is recorded, the exciting voltage (voltage excitation) or exciting current (current excitation) can be integrated with time, and the temperature of the read electrothermal actuator can be integrated with the thermal MEMS actuator. In the working condition, the loss of each actuator can be equivalent by preferentially starting the actuator with the lowest integral value, so that the excessive consumption of the individual actuators is prevented, and the design life is reached in advance.
Proportional control valve (Proportional Valve) refers to a valve controlled factor such as pressure or flow that is proportional to an input signal or exhibits a relatively high linear relationship. For example, a valve driven by a piezoelectric actuator generally has phenomena such as peristaltic motion, hysteresis loop and the like, and has poor linearity. The common practice is to attach piezoelectric sensors on the side surfaces of the actuators to measure the deformation of the actuators and form closed-loop control, so that the linearity is guaranteed to realize proportional control. Most actuators have a degree of linearity problem to a greater or lesser extent.
For cantilever beams and diaphragm actuators, there are traditionally difficulties in achieving measurement of actuation distance. Thus, the linearity of the valve opening control is poor, and it is difficult to improve the accuracy of the flow control. In embodiments of the present invention, the number of actuators that are turned on may be selected via a bond bit line (BitLine), thereby providing more precise control of flow. Taking an actuator array of 100 actuators as an example, the actuators may be configured such that the flow rate at which each actuator is fully open is approximately the same, i.e., a single actuator fully open may achieve a 1% increase in flow rate. Assuming that the accuracy of the proportional opening degree of the individual actuators themselves is 5%, the actuator array can obtain a control accuracy of 0.05%.
In an embodiment of the present invention, the flow control process may include: let the flow to be controlled be Q setpoint The maximum exact measurement that a single actuator can drive is max (Q actr ) Let i=round { Q setpoint /max(Q actr ) Opening i actuators, the sum of the flows of the i actuators being i x max (Q actr ). Opening the (i+1) th valve to set the flow rate of the (i+1) th actuator to Q setpoint -i×max(Q actr )。
When the flow rate of the (i+1) th actuator is low, the flows of the (i-2, i-1, i, 1+1) th actuators can be simultaneously set as (Q) setpoint -i×max(Q actr )+3×max(Q actr ) I/4, or further the i-j, i-j +1, once again, i is chosen, the flow rate of the i+1 total j+2 actuators is set to (Q setpoint -j×max(Q actr ))/(j+2)。
In one embodiment of the invention, pressure multi-zone control can be added, more pressure sensors (for thermal MFCs, heaters and corresponding temperature sensors need to be added in response) are attached to the actuator, and each set of sensors independently detects the pressure (and temperature) of each zone to further precisely control flow.
In one embodiment of the invention, 3 cantilevers of length 1mm and width 100um add up to an area of 0.3mm 2 The arch opening of the cantilever is reduced to a cantilever lifting horizontally by 10um. It was calculated that when the inlet/outlet pressure difference was 1bar, the air passing through was 1.0516903e-5kg/s, which is about 524ml/min air (different kinds of gas The density is different and the gas flow through it is also different at the same operating pressure. ) I.e. 0.3mm 2 Corresponding to a flow rate of 500sccm and a flow rate of 10mm 2 The area of the valve can correspond to 16slm of flow (100 actuators) and 100mm of flow 2 An area valve may correspond to 160slm of flow (1000 actuators).
In another embodiment of the invention, 3 cantilevers of length 1mm and width 100um add up to an area of 0.3mm 2 The arch opening of the cantilever is 15um. It was calculated that when the inlet-outlet pressure difference was 1bar, the air volume flow rate through it was 4.41X 10- 6 m 3 S is equal to 264.6sccm, i.e. 0.3mm 2 Corresponding to 264sccm flow, 10mm 2 The area of the valve can correspond to the flow rate of 8.7s|m (100 actuators), 100mm 2 An area valve may correspond to 87slm of flow (1000 actuators).
Fig. 22 shows a schematic diagram of a micro valve in another embodiment of the invention. As shown in fig. 22, the micro-valve has an actuator array of 2 x 2 actuators, which includes circular diaphragms 2201 and corresponding orifices, each diaphragm 2201 being piezoelectric or otherwise actuated. Each diaphragm 2201 may correspond to one or more orifices (one orifice for each diaphragm 2201 is illustrated in fig. 22), where each diaphragm 2201 corresponds to multiple orifices that may increase the throughput of a single diaphragm. The diaphragm 2201 is connected to the upstream and downstream of the orifice, respectively, the total flow Q of the microvalve total ＝∑Q i ，Q i Indicating the flow of the ith actuator.
As described above, in an embodiment of the present invention, the arrangement of the pressure sensor, the temperature sensor, the heater, and the temperature sensor on the micro valve may form a mass flow meter. In a mass flowmeter, the flow through different actuators can be calculated differently depending on whether the flow is choked flow or not.
Blocking phenomenon means that when the flow velocity at a certain section in the pipe reaches the sound velocity, the flow rate, the pressure of the air flow before the sound velocity section no longer changes, and thus the flow rate remains unchanged, no matter how the pressure outside the pipe outlet decreases. There are many situations where a choked flow is easily formed, and there are supersonic wind tunnel (see wind tunnel) start-up blocking, aircraft air inlet blocking, friction tube blocking, and heating tube blocking.
Taking the blocking in the air inlet of an aircraft as an example, the Mach number Ma of the air flow far ahead of the air inlet 00 <1, the airflow speed in front of the air inlet channel is increased, the flow speed at the throat in the inlet is increased, and the flow is increased; mach number Ma at throat 00 When=1, the airflow speed in front of the air inlet channel is not increased even if the airflow speed is increased again, and the flow is only supersonic flow and shock wave appear behind the throat; mach number Ma of the far front air flow 00 When the flow is more than 1, the supersonic air flow is not disturbed before the inlet and directly flows into the air inlet channel. When the throat area is large enough, all the entering gas can pass through, the air inlet channel is not blocked; when the area of the throat is too small, the flow which can pass through the throat is smaller than the flow which directly enters the throat, the throat is blocked, gas in front of the throat is accumulated, the pressure is increased, an isolated shock wave is formed in front of the inlet, a part of redundant airflow overflows out of the outlet, and a supersonic region and a shock wave appear behind the throat. The blocking in the air inlet channel of the airplane greatly increases the blocking force of the airplane and the thrust of the engine is obviously reduced.
FIG. 23 illustrates a schematic diagram of the airflow at an actuator in one embodiment of the invention. It should be understood that fig. 23 is provided merely as an illustration of the direction of air flow and pressure at the actuator and does not represent the actual configuration of the actuator. As shown in fig. 23, for compressible fluids, if the pressure P of the inlet port of the actuator 1 Keep constant and the pressure at the air outlet P 2 Gradually decreasing, the mass flow through the actuator gradually increases to a maximum value, at which point P is further reduced 2 The flow rate is not increased any more, which is called choked flow. Forming a choked flow typically requires passing P 1 ≥2P 2 (specific ratio is related to specific heat capacity of gas), at this time, the flow rate through the actuator is only related to P 1 Related to P 1 Is proportional to the absolute value of (a).
FIG. 24 is a schematic diagram showing the pressure versus flow rate of a choked flow in an embodiment of the invention. Wherein the blocking point of the fluid is restored by the pressure of the liquidComplex factor F L And critical pressure differential ratio coefficient X of gas without attachment tube T It is decided that the liquid is due to vapor formation, while the gas reaches the speed of sound at the constriction. Wherein the blocking threshold for pressure can be calculated by:
F F ＝0.96-0.28(P V /P C ) 1/2
wherein F is F Representing the critical pressure ratio factor, P of the liquid V Indicating fluid vapor pressure, P C Representing the thermodynamic critical pressure.
Blocking critical pressure P at actuator choked The ratio to P can be expressed as:
where n represents an index of isentropic expansion/compression. For an ideal gas in a thermal system, n is the ratio of specific heats: n=c p /C v Wherein C p Represents specific heat, C at constant pressure v Representing the specific heat of constant volume. Most process vapors operating in the wet zone have n=1.135, superheated vapor n=1.30, air n=1.4, methane n=1.31, and helium n=1.667.
For air, the calculation of the critical pressure ratio can be expressed as:
the correspondence between n of other gases and the critical pressure ratio may be 1.1135, 0.577;1.300, 0.546;1.400 and 0.528;1.667, 0.487.
The mass flow through the actuator of a choked flow, that is, an acoustic velocity flow with a minimum pressure equal to the critical pressure, through the actuator can be expressed as:
wherein m is c Mass flow (kg/s), A, of sonic flow c Representing the nozzle area (m) 2 )、ρ 1 Represents the density of the air inlet of the actuator (kg/m 3 )。
For non-choked flow conditions, pressure function upstream and downstream of the actuatorThe secondary flow can be determined according to the following equation q=k×function (P UP ，P DOWN )。
Flow at an actuator of non-blocking flowSpecifically, the expression can be expressed as follows:
as can be seen from the above formula, at P UP 、P DOWN Unchanged flow Q at actuator of non-blocking flow i In proportion to the open area a of the non-choked flow, the open area a can be regulated in the present invention by an electrical control circuit and is controlled by a control unit.
In non-blocking flows, the flow is limited by the sonic velocity at the outlet of the actuator, when the upstream pressure P UP After determination, flow rate Q i In direct proportion to the open area a of the non-choked flow. By configuring a plurality of actuators 402i, the upstream pressure P of the actuators 402i can be made UPi Substantially remain unchanged so that the effect on back pressure can be minimized. Upstream interconnection of the plurality of actuators 402i creates a pressure differential delta (P) between the actuators when the flow rate (flow velocity) is large and the tube diameter is small UPi ，P UPi+1 )＝v 2 fLρ/2D. According to the invention, the adjusting actuator can maintain P UPi Is substantially unchanged and receives a pressure differential between upstream of the plurality of actuators 402i, vs. the open area A i Fine tuning is performed to achieve accurate proportional control without the need for a pressure control valve to control. Whereas in a pressure flow controlled device the open area at the MFC is fixed, in case of a fixed downstream pressure it is necessary to push up P by pushing up UPi To control the flow. P when the flow ratio changes UPi Increasing the corresponding Q i And also increases.
For choked flow, when Q i When doubling, P UPi Doubles the flow Q at other actuators in general j Will decrease, P UPj Will also decrease due to P UPi And P UPj And the back pressures are mutually communicated, so that the back pressures can interfere with each other and even contradict each other, and the over-constraint condition occurs. When the flow gap is too large, it is difficult to achieve accurate control. The situation is also similar for non-blocking flows.
When the air Flow through the actuator 402i is Choked Flow (Choked Flow), the Flow rate Q at the actuator 402i i ＝C×P UPi Wherein C represents a first correlation coefficient, which is related to the opening area A of i actuators i Positive correlation.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to those skilled in the relevant art that various combinations, modifications, and variations can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention as disclosed herein should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
Claims (20)
1. A microvalve, comprising:
a first substrate having a substrate inlet, wherein gas flows from the substrate inlet to an intermediate layer;
an intermediate layer disposed between the first substrate and the second substrate, the intermediate layer comprising an array formed by a plurality of actuators comprising:
an orifice having a throttle inlet port and a throttle outlet port, wherein gas flows from the throttle inlet port into the orifice and from the throttle outlet port to the second substrate; and
a cantilever configured to move relative to the throttle inlet, wherein an opening area of the throttle inlet is adjusted by adjusting a distance between the cantilever and the throttle inlet; and
a second substrate having a substrate exit port, wherein gas flows from the substrate exit port.
2. The micro valve of claim 1, further comprising:
a housing surrounding the first substrate, the intermediate layer, and the second substrate, the housing having a housing air inlet and a housing air outlet, the housing comprising a metal housing, a ceramic housing, or a resin housing.
3. The micro valve of claim 1, wherein the orifice comprises:
An orifice step connected to the second substrate, wherein the orifice vent is disposed on the orifice step; and
an orifice fence, a first end of which is connected with the first substrate, and a second end of which is opposite to the first end is connected with the orifice step, the orifice intake port being arranged on the orifice fence.
4. The micro valve of claim 3, wherein the first substrate further comprises:
a substrate step connected to a first end of the orifice enclosure, wherein the substrate step and/or the orifice step are configured to inhibit a short circuit airflow created by a gap between the cantilever and the second substrate and/or the first substrate.
5. The micro valve of claim 1, wherein the cantilever has a coating of a wetting material thereon; and/or
The cantilever comprises an electrostatic driving cantilever, an electromagnetic driving cantilever, a piezoelectric driving cantilever or an electrothermal driving cantilever.
6. The micro valve of claim 1, wherein the cantilever is configured for horizontal movement relative to the throttling inlet; or alternatively
The cantilever is configured to move vertically relative to the throttle inlet.
7. The micro valve of claim 1, further comprising:
and an outer frame disposed around the intermediate layer to restrict an air flow.
8. A microvalve of claim 3, wherein said orifice enclosure includes a first orifice inlet and a second orifice inlet opposite said first orifice inlet; and
the boom includes a first boom configured to move relative to the first throttle inlet and a second boom configured to move relative to the second throttle inlet.
9. A microvalve according to claim 1, wherein a grating is provided on one or more of the following to form the laminar element: a substrate air inlet, a substrate air outlet, and a throttle air outlet.
10. The micro valve of claim 1, wherein the cantilever arm is connected to one or more orifices.
11. The micro valve of claim 1, wherein the plurality of micro valves are configured to splice with each other to increase flow.
12. The micro valve of claim 1, wherein the throttle outlets of the plurality of actuators are individually vented or combined into a plurality of groups of post-packet vents to achieve diffuse venting.
13. The micro valve of claim 1, further comprising:
and a control circuit connected to the plurality of actuators, the control circuit being configured to control the opening degrees of the plurality of actuators, respectively.
14. The micro valve of claim 13, wherein the control circuit is configured to:
setting the flow to be controlled as Q setpoint ；
Determining the maximum exact measurement value of a single actuator as max (Q actr )；
Calculating i=rounding { Q setpoint /max(Q actr )}；
Opening i actuators, wherein the sum of the flows of the i actuators is i×max (Q actr ) The method comprises the steps of carrying out a first treatment on the surface of the And
opening the (i+1) th actuator, and setting the flow rate of the (i+1) th actuator to Q setpoint -i×max(Q actr )。
15. The micro valve of claim 14, wherein the control circuit is further configured to:
when the flow rate of the i+1th actuator is below the threshold, the flow rate of the i-j, i-j+1, & i, i+1 total j+2 actuators is set to (Q setpoint -j×max(Q actr ))/(j+2)。
16. A microvalve, comprising:
a first substrate having a substrate inlet, wherein gas flows from the substrate inlet to an intermediate layer;
an intermediate layer disposed between the first substrate and the second substrate, the intermediate layer comprising an array formed by a plurality of actuators comprising:
An orifice having a throttle inlet port and a throttle outlet port, wherein gas flows from the throttle inlet port into the orifice and from the throttle outlet port to the second substrate; and
a diaphragm configured to control an opening degree of the throttle inlet; and
a second substrate having a substrate exit port, wherein gas flows from the substrate exit port.
17. The micro valve of one of claims 1 and 16, wherein the first substrate is configured to restrict gas flow and the second substrate has a substrate gas inlet and a substrate gas outlet, wherein gas flows from the substrate gas inlet to the intermediate layer and flows back to the second substrate before flowing out of the substrate gas outlet.
18. A mass flow meter, comprising:
a micro valve, which is a micro valve according to any one of claims 1 to 17; and
a sensing component disposed on at least one of the plurality of actuators of the micro valve.
19. The mass flow meter of claim 18, wherein the sensing component comprises a pressure sensor and a temperature sensor, wherein the micro-valve, the pressure sensor, and the temperature sensor form a pressure type mass flow meter; and/or
The sensing component includes a heater and a temperature sensor, wherein the micro valve, the heater and the temperature sensor form a thermal mass flow meter.
20. The mass flow meter of claim 19, wherein for choked flow, the flow Q through the ith actuator on the micro valve is adjusted according to i ：
Q i ＝C×P UPi ，
Wherein C represents a first correlation coefficient, P UPi Representing the pressure on the first side of the i-th actuator, wherein the first correlation coefficient C is related to the opening area A of the i-th actuator i Positive correlation; and/or
For non-blocking flow, the flow Q through the ith actuator on the micro valve is adjusted according to i ：
Wherein C' represents a second correlation coefficient, A i Represents the opening area, P, of the ith actuator DOWNi The pressure on the second side of the ith actuator, R, T, M, and γ represent the universal gas constant, the temperature, the molecular mass, the specific heat ratio, and the second phase relation C, which is a constant.
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| CN202310721559.2A CN117109678A (en) | 2023-06-16 | 2023-06-16 | Micro valve and mass flowmeter applied to same |
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| CN202310721559.2A CN117109678A (en) | 2023-06-16 | 2023-06-16 | Micro valve and mass flowmeter applied to same |
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