CN112228628B - Flow control method of piezoelectric micro valve and piezoelectric micro valve device - Google Patents

Flow control method of piezoelectric micro valve and piezoelectric micro valve device Download PDF

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Publication number
CN112228628B
CN112228628B CN202011149625.6A CN202011149625A CN112228628B CN 112228628 B CN112228628 B CN 112228628B CN 202011149625 A CN202011149625 A CN 202011149625A CN 112228628 B CN112228628 B CN 112228628B
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valve
silicon
piezoelectric
flow
reed
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CN112228628A (en
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匡双阳
宋培义
涂良成
李自学
汪典
张开
索晓晨
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F16K99/0003—Constructional types of microvalves; Details of the cutting-off member
    • F16K99/0015—Diaphragm or membrane valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K99/0001—Microvalves
    • F16K99/0034—Operating means specially adapted for microvalves
    • F16K99/0042—Electric operating means therefor
    • F16K99/0048—Electric operating means therefor using piezoelectric means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K2099/0073—Fabrication methods specifically adapted for microvalves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K99/00—Subject matter not provided for in other groups of this subclass
    • F16K2099/0082—Microvalves adapted for a particular use
    • F16K2099/0096—Fuel injection devices

Abstract

The invention belongs to the field of piezoelectric micro-valve structures, and particularly discloses a flow control method of a piezoelectric micro-valve and a piezoelectric micro-valve device, wherein the control method comprises the following steps: the capacitance of a displacement detection capacitor is detected in real time, and the displacement detection capacitor is arranged on two radial sides of a valve flow passage of the piezoelectric micro valve; determining the current flow resistance of a valve flow channel by taking the capacitance as a feedback signal, and further determining the current flow; according to the current flow, the input voltage of the piezoelectric ceramics in the piezoelectric micro valve is changed to adjust the size of the valve flow channel, so that the flow of the piezoelectric micro valve is controlled at a stable level. In addition, the valve flow channel is composed of a valve inlet, a valve outlet and a gap between the silicon reed and the silicon valve bottom, and the silicon reed and the edge of the silicon valve bottom can be bonded and sealed by adopting an MEMS (micro-electromechanical systems) process. The invention can avoid the different displacement of the piezoelectric ceramics in the voltage boosting and reducing processes caused by the existence of the piezoelectric ceramics electric hysteresis loop characteristics, improve the flow regulation precision and reduce the flow noise.

Description

Flow control method of piezoelectric micro valve and piezoelectric micro valve device
Technical Field
The invention belongs to the field of piezoelectric micro valve structures, and particularly relates to a flow control method of a piezoelectric micro valve and a piezoelectric micro valve device.
Background
The valve is a key node technology in most gas-liquid transportation processes, and is very commonly applied to vacuum equipment, gas-liquid transportation equipment, medicine supply equipment and a microfluidic system. However, some gas-liquid transportation processes have very strict requirements on valves, such as the transportation of a gas working medium by a hall propeller and the transportation of a liquid working medium by a colloid propeller, the extremely high flow regulation precision and the extremely low flow control noise are realized by the valves.
Obviously, for a Hall thruster and a colloid thruster, the electronic control of the valve is inevitable, and the most common electronic control means for the high-precision micro valve is realized by controlling the elongation of the piezoelectric ceramic through power supply equipment. However, because of the hysteresis loop characteristic between the piezoelectric ceramic control voltage and the elongation, the control voltage of the valve is actually different in the elongation in the processes of increasing and decreasing, and thus the same voltage can output different flow rates.
However, the stringent requirements for valves are present in micro-propulsion spacecraft. For example, the colloid propeller firstly requires the valve to have a very low leakage rate, and secondly the working medium transport flow of the colloid propeller is directly related to the thrust, because of the existence of the piezoelectric ceramic hysteresis loop, the same output voltage of the power supply can cause the valve to output different flows, thereby outputting different thrusts, and the traditional piezoelectric micro valve is difficult to satisfy the requirement of the colloid propeller. Similar problems exist for hall thrusters.
Disclosure of Invention
The invention provides a flow control method of a piezoelectric micro valve and a piezoelectric micro valve device, which are used for solving the technical problem that the existing piezoelectric micro valve is difficult to meet the scene with severe requirements on flow control resolution and noise, such as a colloid propeller, a Hall propeller and the like.
The technical scheme for solving the technical problems is as follows: a flow control method of a piezoelectric microvalve, comprising:
the method comprises the steps of detecting the capacitance of a displacement detection capacitor in real time, wherein the displacement detection capacitor is arranged on two radial sides of a valve flow passage of a piezoelectric micro valve; determining the current flow resistance of the valve flow channel by taking the capacitance as a feedback signal, and further determining the current flow; and according to the current flow, changing the input voltage of the piezoelectric ceramic in the piezoelectric micro valve to adjust the size of the valve flow channel, so that the flow of the piezoelectric micro valve is controlled at a stable level.
The invention has the beneficial effects that: the method integrates the capacitor into the piezoelectric micro valve, the flow resistance is fed back according to the size of the capacitor, the flow rate is fed back, the capacitance is used as a feedback signal through a closed-loop feedback design, the piezoelectric ceramic is used as a feedback actuator, and the flow rate transported by the valve is maintained at a stable level, so that the phenomenon that the displacement of the piezoelectric ceramic is different in the pressure boosting and reducing processes due to the existence of the characteristics of the piezoelectric ceramic hysteresis loop is avoided, the stability of flow output is ensured, the flow rate regulation precision is improved, and the flow noise is reduced. Therefore, the method is a method for improving the flow regulation precision and reducing the flow noise.
On the basis of the technical scheme, the invention can be further improved as follows.
Further, the valve flow channel is composed of a valve inlet, a valve outlet and a gap between the silicon reed and the silicon valve bottom, wherein the silicon reed and the edge of the silicon valve bottom are bonded and sealed by adopting an MEMS (micro-electromechanical systems) process.
The invention has the further beneficial effects that: the inlet and the outlet of the valve are both arranged on the valve bottom, and the silicon reed and the silicon valve bottom are bonded and connected by an MEMS bonding process, so that a flow channel environment with good sealing property can be formed between the inlet and the outlet. The piezoelectric ceramic is controlled by the power supply equipment to generate elongation, and the piezoelectric ceramic drives the silicon reed to generate displacement, so that the flow resistance of a flow channel is controlled, and the controllable high-precision flow regulation of the gas/liquid working medium can be realized under the fixed pressure difference of an inlet and an outlet.
The present invention also provides a piezoelectric microvalve device comprising: silicon reed, at the bottom of the silicon valve, T type support and two piezoceramics still include: a displacement detection capacitor and a controller;
the two piezoelectric ceramics are symmetrically and vertically arranged on two sides of the surface of the silicon reed, the upper end surfaces of the two piezoelectric ceramics are fixedly connected with two sides of the T-shaped support, and the lower end of the middle part of the T-shaped support is vertically connected with a silicon valve core of the silicon reed; the lower end face of the silicon valve core is provided with one metal electrode of the displacement detection capacitor, the position, opposite to the one metal electrode, of the upper end face of the silicon valve bottom is provided with the other metal electrode of the displacement detection capacitor, holes penetrating through the silicon valve bottom are formed in the silicon valve bottom and are respectively used as a valve inlet and a valve outlet, and the controller is connected with the electrode plate of the displacement detection capacitor so as to control voltage applied to the two piezoelectric ceramics according to the detected size of the capacitor.
The invention has the beneficial effects that: the device can integrate the two polar plates of the capacitor on the silicon reed and the silicon valve bottom respectively in the MEMS process, and in the deformation process of the silicon reed, the size of the capacitor formed by the two metal polar plates corresponds to the displacement of the valve core of the silicon reed one by one, the displacement of the valve core corresponds to the flow resistance of the flow channel one by one, and the flow resistance of the flow channel corresponds to the gas-liquid transport flow one by one, so that the flow can be detected by detecting the size of the capacitor. The size of the capacitor is used as a feedback quantity, the piezoelectric ceramic is used as a feedback actuator, and the capacitor can be controlled to be maintained at a given capacitance value through closed-loop feedback design, so that the transport flow can be maintained at a given flow value.
Further, an MEMS (micro-electromechanical systems) process is adopted, the silicon reed and the edge of the bottom of the silicon valve are in bonding sealing connection through three bonding layers, and a flow channel of the valve is formed by the inlet, the outlet and a sealing space between the silicon reed and the bottom of the silicon valve.
The invention has the further beneficial effects that: and the silicon reed and the silicon valve bottom are bonded and connected by using an MEMS bonding process, so that a flow channel environment with good sealing property can be formed between the outlet and the inlet. The piezoelectric ceramic is controlled by the power supply equipment to generate elongation, and the piezoelectric ceramic drives the silicon reed to generate displacement, so that the flow resistance of a flow channel is controlled, and the controllable high-precision flow regulation of the gas/liquid working medium can be realized under the fixed pressure difference of an inlet and an outlet.
Further, the overall thickness of the trilayer bonding layer is less than 1000 nanometers.
The invention has the further beneficial effects that: due to the existence of the bonding layer, when the valve is closed, the middle part of the silicon reed needs to be bent downwards so that two polar plates of the displacement detection capacitor are contacted, and the valve is closed. Therefore, the smaller the overall thickness of the three-layer bonding layer, the easier it is to achieve the closed state of the valve in terms of process.
Furthermore, the silicon valve bottom is connected in the metal valve bottom frame in an embedded mode through sealing glue, the positions, opposite to the inlet holes and the outlet holes in the silicon valve bottom, of the metal valve bottom frame are also provided with the inlet holes and the outlet holes, the two inlet holes are coaxially aligned, and the two outlet holes are coaxially aligned.
Furthermore, the thickness of the silicon reed is controlled by adopting an MEMS (micro electro mechanical system) process, and the flow control range is improved by reducing the thickness of the silicon reed.
The invention has the further beneficial effects that: the thickness of the silicon reed is controlled by using an MEMS (micro electro mechanical system) process, and the smaller the thickness of the silicon reed is, the smaller the rigidity of the silicon reed is, so that under the same tensile stress, the larger the displacement of the silicon valve core is, the lower the flow resistance of a flow channel is, and the larger the flow control range is.
Furthermore, by designing the sizes of the T-shaped support and the valve bottom frame and selecting the adhesive, the silicon reed is ensured to generate initial deformation when the voltage source output voltage is zero and the valve is in a closed state after all components of the piezoelectric micro valve are assembled, at the moment, two electrode plates of the displacement detection capacitor are contacted, and the flow resistance of a valve flow channel is infinite.
The invention has the following further beneficial effects: an effective method for making the silicon reed initially deformed so that two electrode plates of the displacement detection capacitor are contacted is provided.
Drawings
Fig. 1 is a schematic diagram illustrating a flow control of a piezoelectric micro valve according to an embodiment of the present invention;
FIG. 2 is a schematic view of a piezoelectric microvalve device according to an embodiment of the present invention;
fig. 3 is an overall structural view of a piezoelectric microvalve device according to an embodiment of the present invention;
FIG. 4 is a characteristic diagram of the hysteresis loop of the piezoelectric ceramic provided in the embodiment of the present invention;
FIG. 5 is an expanded view of the assembled components of a piezoelectric microvalve device provided in accordance with an embodiment of the present invention;
FIG. 6 is a block diagram of a valve flow channel provided in accordance with an embodiment of the present invention;
fig. 7 is a flow channel structure diagram of a piezoelectric micro valve in a closed state according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a method for increasing a flow control range of a valve according to an embodiment of the present invention.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
101 is a T-shaped support, 102 is a valve bottom frame, 103 and 104 are two piezoelectric ceramics, 105 is a silicon reed, 106 is a silicon valve core, 201, 202 and 203 are bonding layers, 204 is a silicon valve bottom, 205 and 206 are capacitance plates of displacement detection capacitors, 207 is a flow channel inlet on the silicon valve bottom, 208 is a flow channel outlet on the silicon valve bottom, 209 is a flow channel inlet on the valve bottom frame, and 210 is a flow channel outlet on the valve bottom frame.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example one
A flow control method of a piezoelectric microvalve, comprising:
the capacitance of a displacement detection capacitor is detected in real time, and the displacement detection capacitor is arranged on two radial sides of a valve flow passage of the piezoelectric micro valve; determining the current flow resistance of the valve flow channel by taking the capacitance as a feedback signal, and further determining the current flow rate; according to the current flow, the input voltage of the piezoelectric ceramics in the piezoelectric micro valve is changed to adjust the size of the valve flow channel, so that the flow of the piezoelectric micro valve is controlled at a stable level.
For example, according to the closed-loop feedback control principle of the piezoelectric micro valve shown in fig. 1, after the capacitance is detected, a control quantity is obtained by comparing the capacitance with a given value, so as to control the voltage magnitude input to the piezoelectric ceramic.
Integrate the electric capacity to the piezoelectricity micro valve in, thereby the size of the size feedback flow resistance through the electric capacity feeds back the size of flow, through closed loop feedback design, use the electric capacity size as feedback signal, piezoceramics is feedback executor, transport the flow with the valve and maintain the stable level, so then avoided because of the existence of piezoceramics hysteresis loop characteristics lead to step up and step down the displacement of in-process piezoceramics different, thereby guarantee flow output's stability, the regulation precision of flow has been improved, flow noise has been reduced. Therefore, the method is a method for improving the flow regulation precision and reducing the flow noise.
Preferably, the valve flow channel is formed by a valve inlet, a valve outlet and a gap between the silicon reed and the silicon valve bottom, and the silicon reed and the edge of the silicon valve bottom are bonded and sealed by adopting an MEMS (micro-electromechanical systems) process.
Firstly, the inlet and the outlet of the valve are both arranged on the valve bottom, and the silicon reed and the silicon valve bottom are bonded and connected by the MEMS bonding process, so that a flow channel environment with good sealing performance can be formed between the inlet and the outlet. The piezoelectric ceramic is controlled by the power supply equipment to generate elongation, and the piezoelectric ceramic drives the silicon reed to generate displacement, so that the flow resistance of a flow channel is controlled, and the controllable flow regulation of the gas/liquid working medium can be realized under the fixed pressure difference of an inlet and an outlet. In addition, in the MEMS process, two electrode plates of a capacitor are respectively integrated on the silicon reed and the bottom of a silicon valve, in the deformation process of the silicon reed, the size of the capacitor formed by the two metal electrode plates corresponds to the displacement of a valve core of the silicon reed one by one, the displacement of the valve core corresponds to the flow resistance of a flow channel one by one, and the flow resistance of the flow channel corresponds to the gas-liquid transport flow one by one, so that the flow can be detected by detecting the size of the capacitor. The capacitance is used as feedback quantity, the piezoelectric ceramic is used as a feedback actuator, and the capacitance can be controlled to be maintained at a given capacitance value through closed-loop feedback design, so that the transport flow is maintained at a given flow value, the flow regulation precision is further improved, and the flow noise is reduced.
Example two
A piezoelectric microvalve device, as shown in fig. 2, comprising: silicon reed, at the bottom of the silicon valve, T type support and two piezoceramics still include: displacement detection capacitance and a controller.
The two piezoelectric ceramics are symmetrically and vertically arranged on two sides of the surface of the silicon reed, the upper end surface of the two piezoelectric ceramics is fixedly connected with two sides of the T-shaped support, and the lower end of the middle part of the T-shaped support is vertically connected with a silicon valve core of the silicon reed; one of the metal electrodes of the displacement detection capacitor is arranged on the lower end face of the silicon valve core, the other metal electrode of the displacement detection capacitor is arranged at the position, opposite to the one metal electrode, of the upper end face of the silicon valve bottom, holes penetrating through the silicon valve bottom are formed in the two sides of the other metal electrode on the silicon valve bottom and are used as a valve inlet and a valve outlet respectively, and the controller is connected with the output of the displacement detection capacitor so as to control the voltage applied to the two piezoelectric ceramics according to the detected size of the capacitor.
As shown in fig. 3, the T-shaped bracket 101 and the valve bottom frame 102 are made by a conventional finishing process. The T-shaped support 101 and the valve bottom frame 102 are connected by two piezo ceramic stacks 103 and 104. The piezoelectric ceramic stacks 103 and 104 are controlled by a voltage source, when the voltage output by the voltage source is zero, the piezoelectric ceramic stacks 103 and 104 have no elongation, and when the voltage output by the voltage source is a certain positive value, the piezoelectric ceramic stacks 103 and 104 have an elongation corresponding to the voltage. However, the same voltage corresponds to different elongations during the voltage rising and falling, which is determined by the hysteresis loop characteristics of the piezoelectric ceramic, as shown in fig. 4.
When the voltage source outputs a positive voltage, the piezoelectric ceramic stacks 103 and 104 have the same extension, because the T-shaped support 101 is a rigid structure, the T-shaped support 101 drives the valve element 106 of the silicon reed 105 to generate a deformation amount perpendicular to the plane of the silicon reed 105, which is the same as the extension of the piezoelectric ceramic stacks. The attachment of silicon reed 105 to valve base frame 102 is shown in fig. 5. The silicon reed 105 and the silicon valve bottom 204 are bonded and hermetically connected through three bonding layers 201, 202 and 203. The silicon valve base 204 is connected to the valve base frame 102 by a sealant. The valve bottom frame 102 has two through holes, an inlet hole 209 and an outlet hole 210. The silicon valve bottom 204 also has two through holes, an inlet hole 207 and an outlet hole 208. The apertures of inlet opening 207/209 and outlet opening 208/210 are identical (or not identical, without limitation). The silicon valve base 204 is coupled to the valve base frame 102 with the inlet ports 207 and 209 coaxially aligned and the outlet ports 208 and 210 coaxially aligned.
Fig. 6 shows a flow passage structure of the valve. The silicon reed 105 and the silicon valve bottom 204 are bonded and hermetically connected through three bonding layers 201, 202 and 203. The bonding layers 201, 203 are titanium material and the bonding layer 202 is gold material. The total thickness of the bonding layer 201/202/203 is within 1000 nanometers, and a valve silicon reed and a valve bottom are bonded by using an MEMS bonding process, so that the sealing performance of a valve flow channel is optimized, and the method for improving the sealing performance of the valve is provided. The metal electrode 205 is arranged at the geometric center of the lower surface of the silicon valve core 106, the metal electrode 206 is arranged at the geometric center of the upper surface of the silicon valve bottom, and the thicknesses of the metal electrodes 205 and 206 are in the nanometer order of magnitude. The metal electrodes 205 and 206 are completely opposed to each other to constitute a displacement detection capacitance. The flow path of the valve is formed by the inlet 207, the outlet 208 and the sealed space between the silicon reed 105 and the silicon valve bottom 204.
The voltage source outputs zero voltage and the valve is in a closed state. The amount of expansion of piezo stack 103/104 is zero at this time. Note that the total thickness of the bonding layer 201/202/203 is D, the total thickness of the capacitor plate 205/206 is D, when no external force is applied, the state of the flow channel structure and the state of the silicon valve core 106 are as shown in fig. 6, the silicon valve core has no deformation, and a certain external force can be applied to deform the silicon valve core 106 by a distance D-D, so that the capacitor plate 205/206 is in contact with the capacitor plate when the valve is in a closed state, as shown in fig. 7, the valve is guaranteed to have an extremely low leakage rate. Before this external force is applied, a suitable adhesive is uniformly applied to the contact interface between the piezoceramic stack 103/104 and the valve base 102 and T-bracket 101, and the contact interface between the T-bracket and the silicon spool 106, and then the external force is applied to the T-bracket until the external force is removed after the adhesive is cured. When the valve is in a closed state, the positive electrode plate 205/206 and the negative electrode plate 205/206 of the capacitor are in contact, the flow resistance of the valve flow channel is infinite, the valve flow approaches zero in a certain inlet-outlet pressure difference range, and the valve leakage rate approaches zero.
At this time, since the positive and negative electrode plates 205/206 of the capacitor are in contact, the capacitance is zero, and the corresponding valve displacement is zero. When the voltage source outputs a forward voltage, the piezoelectric ceramic stacks 103 and 104 drive the silicon valve core 106 on the silicon reed 105 to generate a displacement perpendicular to the silicon reed through the T-shaped support 101, and the displacement of the silicon reed is in one-to-one correspondence with the flow resistance of the flow channel. Therefore, the flow resistance of the flow channel can be adjusted through the output voltage of the voltage source, and the flow of the valve can be adjusted.
Because the capacitance formed by the positive and negative electrode plates 205/206 corresponds to the displacement of the silicon valve element 106, i.e., the elongation of the piezoceramic stack 103/104, the displacement of the valve element 106 can be measured by measuring the capacitance formed by the positive and negative electrode plates 205/206, and the capacitance formed by the positive and negative electrode plates 205/206 can be ensured to maintain a fixed value through a closed-loop feedback design, so that the transport flow can be ensured to maintain a fixed value. The closed loop feedback control principle is shown in fig. 1. The capacitance detection circuit detects the size of the capacitance formed by the positive and negative electrode plates 205/206, converts the preset flow value into capacitance values corresponding to the positive and negative electrode plates 205/206 one by one, inputs the capacitance values into the comparator as a given value together with the detected capacitance values, controls the voltage source to output a control voltage by the control quantity output by the comparator through algorithm programs such as PID control algorithm, controls the voltage to control the piezoelectric ceramic to generate an elongation quantity, namely, a valve core displacement quantity, namely, the displacement quantity of the capacitance electrode plates 205, then the capacitance detection circuit detects the size of a new capacitance, inputs the new capacitance into the feedback loop, so as to form a closed loop control loop, until the capacitance detected by the capacitance detection circuit is equal to the given value, the whole control process can ensure that the size of the capacitance is stabilized at the given value, and can ensure that no matter whether the voltage of the voltage source rises or falls, the transport flow of the micro-valve can be maintained at a fixed value.
Preferably, the thickness of the silicon reed is controlled by adopting an MEMS (micro electro mechanical system) process, and the flow control range is further improved by reducing the thickness of the silicon reed.
The thickness of the silicon reed is controlled by using an MEMS (micro electro mechanical system) process, and the smaller the thickness of the silicon reed is, the smaller the rigidity of the silicon reed is, so that the larger the displacement of the silicon valve core is under the same tensile stress, the lower the flow resistance of a flow channel is, and the larger the flow control range is. As shown in fig. 8, the thickness value of the reed in the middle recess between the valve core and the edge of the silicon reed, i.e. the size of the parameter L, can be controlled by the MEMS process, and the smaller the L, the larger the flow control range, which is a method for increasing the flow control range of the valve.
In summary, the present embodiment provides a piezoelectric microvalve with very high flow control resolution and very low noise based on the MEMS technology, in which a deformable silicon reed and a silicon valve bottom with an inlet and an outlet are processed by the MEMS technology, the silicon reed and the silicon valve bottom form a closed flow channel through a gold-titanium bond, a power device controls piezoelectric ceramics to generate precise displacement, and the piezoelectric ceramics controls a distance between the silicon reed and the silicon valve bottom, so as to control a flow resistance of the flow channel. Therefore, on the premise that a pressure difference is formed between the inlet and the outlet, the flow of the transported working medium can be controlled through the power supply equipment. Meanwhile, a displacement detection capacitor is integrated between the silicon reed and the bottom of the silicon valve, the size of the detection capacitor corresponds to the extension of the piezoelectric valve and the flow of the valve one by one, and the valve can be in a given flow level through closed-loop feedback control.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (6)

1. A piezoelectric microvalve device comprising: silicon reed, at the bottom of the silicon valve, T type support and two piezoceramics, its characterized in that still includes: a displacement detection capacitor and a controller;
the two piezoelectric ceramics are symmetrically and vertically arranged on two sides of the surface of the silicon reed, the upper end surfaces of the two piezoelectric ceramics are fixedly connected with two sides of the T-shaped support, and the lower end of the middle part of the T-shaped support is vertically connected with a silicon valve core of the silicon reed; one metal electrode of the displacement detection capacitor is arranged on the lower end face of the silicon valve core, the other metal electrode of the displacement detection capacitor is arranged at the position, opposite to the one metal electrode, of the upper end face of the silicon valve bottom, holes penetrating through the silicon valve bottom are formed in the silicon valve bottom on the two sides of the other metal electrode and are used as a valve inlet and a valve outlet respectively, and the controller is connected with the metal electrodes of the displacement detection capacitor so as to control the voltage applied to the two piezoelectric ceramics according to the detected size of the capacitor;
bonding and sealing the silicon reed and the edge of the silicon valve bottom by three bonding layers by adopting an MEMS (micro-electromechanical systems) process, wherein a flow passage of the valve is formed by the inlet, the outlet and a sealing space between the silicon reed and the silicon valve bottom;
the T-shaped support and the valve bottom frame are connected through two piezoelectric ceramics, the piezoelectric ceramics are controlled by a voltage source, when the voltage output by the voltage source is zero, the piezoelectric ceramics have no elongation, the valve is in a closed state, and metal electrodes of the displacement detection capacitor are in contact; when the voltage output by the voltage source is a certain positive value, the piezoelectric ceramic has an elongation corresponding to the voltage.
2. A piezoelectric microvalve gate device of claim 1, wherein said three bonding layers have an overall thickness of less than 1000 nanometers.
3. The piezoelectric microvalve device of claim 1, wherein said silicon valve base is insert-connected in a valve base frame by a sealant, and an inlet and an outlet coaxially aligned with the inlet and the outlet on said silicon valve base are provided at positions of said valve base frame opposed to the inlet and the outlet on said silicon valve base, respectively.
4. A piezoelectric microvalve gate device as claimed in claim 1, wherein a thickness of said silicon reed is controlled by MEMS process, and a flow control range is increased by reducing the thickness of said silicon reed.
5. The piezoelectric microvalve device of claim 4, wherein said T-shaped support and said valve bottom frame are dimensioned and selected with adhesives to ensure that after all components of the piezoelectric microvalve are assembled, when the voltage source output voltage is zero and the valve is in a closed state, said silicon reed generates an initial deformation, when two metal electrodes of the displacement sensing capacitor are in contact, the flow resistance of the valve flow path is infinite.
6. A flow control method of a piezoelectric microvalve applied to the piezoelectric microvalve device defined in any one of claims 1 to 5, comprising:
the method comprises the steps of detecting the capacitance of a displacement detection capacitor in real time, wherein the displacement detection capacitor is arranged on two radial sides of a valve flow passage of a piezoelectric micro valve; determining the current flow resistance of the valve flow channel by taking the capacitance as a feedback signal, and further determining the current flow; according to the current flow, changing the input voltage of piezoelectric ceramics in the piezoelectric micro valve to adjust the size of the valve flow channel, so that the flow of the piezoelectric micro valve is controlled at a stable level;
the valve flow channel is composed of a valve inlet, a valve outlet and a gap between the silicon reed and the silicon valve bottom, wherein the silicon reed and the edge of the silicon valve bottom are bonded and sealed by adopting an MEMS (micro-electromechanical systems) process.
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CN107771258A (en) * 2015-06-25 2018-03-06 伊利诺斯工具制品有限公司 Piezoelectric actuated type valve

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