MEMS resonant double-chamber pneumatic-electric conversion method and device

Abstract

The invention discloses a gas-electricity conversion method and a gas-electricity conversion device for MEMS (Micro Electro Mechanical System) resonant double chambers. According to the method, the change of a measuring gap between a measuring head and a workpiece to be measured can be converted into differential frequency output of two or four quartz resonators in the double chambers. According to the invention, the two resonance pressure conversion parts are utilized to convert the gas pressure of the gas supply chamber and the gas pressure of the measurement chamber into the frequency difference of the working resonator and the compensation resonator on the same resonance pressure conversion part. And excitation, frequency detection and differential output of a plurality of resonators are realized by using a self-excited oscillation-differential frequency detection circuit. According to the invention, the anti-interference capability of the pneumoelectric conversion device to the fluctuation of the air source and the environment temperature is improved, the overall size is reduced, the stability is improved, the precision is improved, the output is a quasi-digital frequency signal, the extra A / D conversion step and the precision loss in the conversion process are eliminated, and the reliability and the stability of the output signal are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of measurement, relates to high-precision pneumatic measurement, and particularly relates to a MEMS resonant dual-chamber pneumatic-electric conversion method and device. Background Art

[0002] Pressure-type pneumatic measurement is a method that utilizes the one-to-one correspondence between the compressed gas pressure in the internal chamber and the size of the workpiece to be measured to achieve measurement. It has the advantages of high measurement accuracy, high resolution, good stability, small measurement force, long service life, and low price. Due to its certain self-cleaning ability, it has been widely used in high-end manufacturing fields such as aerospace, national defense, semiconductor chips, medical devices, and the automotive industry.

[0003] To improve the versatility of pneumatic measurement technology, researchers have proposed a method of using a pneumatic-electric conversion device in combination with various types of pneumatic measurement heads to achieve precise measurement of different types of geometric dimensions. As the core component of the pneumatic measurement system, the performance of the pneumatic-electric conversion device directly affects the measurement accuracy of geometric dimensions. However, the existing pneumatic-electric conversion devices have low accuracy and poor stability, and it is difficult to meet the requirements for precise measurement of geometric dimensions in high-end equipment manufacturing. The measurement accuracy of the pneumatic-electric conversion device is mainly directly related to the pressure conversion component, and the pressure conversion component can be divided into two types: traditional mechanical and MEMS. Traditional mechanical pressure conversion components represented by bellows are large in volume, low in accuracy, and poor in dynamic performance, which is not conducive to the miniaturization and performance improvement of the pneumatic-electric conversion device. Piezoresistive and piezoelectric MEMS pressure conversion components can be used in the pneumatic-electric conversion device to improve the dynamic characteristics and overall size, but these components usually have poor temperature characteristics and there will be problems of accuracy loss during the analog-to-digital conversion process. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a MEMS resonant dual-chamber pneumatic-electric conversion method and device to improve the performance such as accuracy, stability, and response speed of the pneumatic-electric conversion device.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] In the first aspect of the present invention, a MEMS resonant dual-chamber pneumatic-electric conversion device is provided, which includes a gas conversion component, a first resonant pressure conversion component, and a second resonant pressure conversion component;

[0007] The gas conversion component has a dual-chamber structure, including a gas supply chamber and a measurement chamber that are connected and communicate with each other. The gas supply chamber is connected to a gas source through an air inlet joint, and the measurement chamber is connected to a pneumatic measurement head through an air outlet joint;

[0008] The first resonant pressure conversion component includes a first pressure-sensitive diaphragm and a first working resonator disposed on the first pressure-sensitive diaphragm. The first pressure-sensitive diaphragm is connected to the measurement chamber through a first air inlet hole;

[0009] The second resonant pressure conversion component includes a second pressure-sensitive diaphragm and a second working resonator disposed on the second pressure-sensitive diaphragm. The second pressure-sensitive diaphragm is connected to the air supply chamber through a second air inlet hole;

[0010] The change in the measurement gap s between the pneumatic measuring head and the workpiece is characterized by the difference in the resonant frequencies of the first working resonator and the second working resonator.

[0011] In a second aspect of the present invention, the first resonant pressure conversion component of the MEMS resonant dual-chamber pneumatic-electric conversion device further includes: a first compensation resonator; the second resonant pressure conversion component of the MEMS resonant dual-chamber pneumatic-electric conversion device further includes: a second compensation resonator;

[0012] The change in the internal gas pressure of the measurement chamber is converted into the frequency difference Δf between the first working resonator and the first compensation resonator b ; the change in the internal gas pressure of the air supply chamber is converted into the frequency difference Δf between the second working resonator and the second compensation resonator a ;

[0013] The change in the measurement gap s is characterized by the differential output Δf of Δf a and Δf b .

[0014] In one embodiment, the MEMS resonant dual-chamber pneumatic-electric conversion device further includes: a first self-excited oscillation-differential frequency detection circuit and a second resonant pressure conversion component;

[0015] The first self-excited oscillation-differential frequency detection circuit generates an excitation signal to make the first working resonator and the first compensation resonator work in a resonant state, and detects and outputs the frequency difference Δf between the two resonators b ;

[0016] The second self-excited oscillation-differential frequency detection circuit generates an excitation signal to make the second working resonator and the second compensation resonator work in a resonant state, and detects and outputs the frequency difference Δf between the two resonators a .

[0017] In one embodiment, each working resonator is installed in the working area of the corresponding pressure-sensitive diaphragm to directly characterize the air pressure in the corresponding chamber; each compensation resonator is installed in the non-working area of the corresponding pressure-sensitive diaphragm to reduce the frequency drift caused by temperature interference through the common-mode rejection principle; stress concentration grooves aligned with the corresponding air inlets are machined in the working areas of the pressure-sensitive diaphragms.

[0018] In one embodiment, each resonator is a quartz resonator, which is a double-ended clamped tuning fork fabricated based on MEMS technology and operates in its in-plane symmetric reverse vibration mode in combination with surface electrodes.

[0019] In one embodiment, each pressure-sensitive diaphragm is a silicon pressure-sensitive diaphragm, which is a strain diaphragm fabricated by MEMS technology. Four bosses are machined on its upper surface for installing the working and compensation resonators, and the lower surface of the diaphragm corresponding to the working resonator is directly in contact with the gas in the corresponding chamber.

[0020] In one embodiment, the air supply chamber and the measurement chamber are connected and communicated through a replaceable throttle orifice; a first sealing plug is arranged in the air supply chamber, and the first sealing plug is opposite to the disassembly and assembly part of the replaceable throttle orifice.

[0021] In one embodiment, the gas pressure P x in the measurement chamber has a one-to-one "S"-shaped curve relationship with the measurement gap s, and there is a linear region on this "S"-shaped curve that meets the actual measurement application.

[0022] In the third aspect of the present invention, a MEMS resonant dual-chamber gas-electric conversion method is provided, which is implemented based on the MEMS resonant dual-chamber gas-electric conversion device described in the first aspect of the present invention. Compressed gas is introduced into the air supply chamber and the measurement chamber through an air inlet joint. After the gas pressures in the air supply chamber and the measurement chamber are stable, the measurement gap s between the pneumatic measuring head and the workpiece is measured. The change in the measurement gap s is converted into the change in the gas pressure P x in the measurement chamber, which subsequently causes the first pressure-sensitive diaphragm in direct contact with it to undergo strain d 2 , thereby changing the resonant frequency f 3 of the first working resonator;

[0023] Meanwhile, the change in the gas pressure P c in the air supply chamber is converted into the strain d 1 of the second pressure-sensitive diaphragm, thereby changing the resonant frequency f 2 of the second working resonator;

[0024] The change in the measurement gap s between the pneumatic measuring head and the workpiece is characterized by the difference between f 3 and the second f 2 .

[0025] In a fourth aspect of the present invention, there is provided a MEMS resonant dual-chamber gas-electric conversion method, which is implemented based on a MEMS resonant dual-chamber gas-electric conversion device described in the second aspect of the present invention. Compressed gas is introduced into the air supply chamber and the measurement chamber through an air inlet joint. After the gas pressures in the air supply chamber and the measurement chamber are stabilized, a pneumatic measuring head is used to measure the measurement gap s between the workpiece.

[0026] The change in the measurement gap s is converted into a change in the gas pressure P in the measurement chamber x , which subsequently causes the first pressure-sensitive diaphragm in direct contact with it to undergo strain d 2 , thereby changing the resonant frequency f of the first working resonator 3 . At the same time, the first compensation resonator compensates for the error caused by the ambient temperature based on the common-mode rejection principle. The change in P x is converted into the frequency difference Δf between the two resonators b ;

[0027] Meanwhile, the change in the gas pressure P in the air supply chamber c is converted into the strain d of the second pressure-sensitive diaphragm 1 , thereby changing the resonant frequency f of the second working resonator 2 . At the same time, the second compensation resonator compensates for the error caused by the ambient temperature based on the common-mode rejection principle. The change in P c is converted into the frequency difference Δf between the second working resonator and the second compensation resonator a ;

[0028] The change in the measurement gap s between the pneumatic measuring head and the workpiece is characterized by the differential output Δf of Δf a and Δf b .

[0029] Compared with the prior art, the output of the present invention is a quasi-digital frequency signal, eliminating the additional A / D conversion step and the accuracy loss during the conversion process, and enhancing the reliability and stability of the output signal. A novel gas-electric conversion device provided by the present invention adopts a dual-chamber gas conversion component, reducing the error caused by the gas source and environmental fluctuations, and improving the accuracy and stability. In addition, the present invention adopts a common-mode differential resonant pressure conversion component manufactured based on MEMS technology, weakening the interference of environmental temperature changes, which is beneficial to reducing the overall size and improving the accuracy of the gas-electric conversion device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a schematic diagram of the principle of the gas-electric conversion method according to a preferred embodiment of the present invention.

[0031] Figure 2It is a schematic diagram of the overall structure of the preferred embodiment of the present invention.

[0032] Figure 3 It is a bottom view schematic diagram of the preferred embodiment of the present invention.

[0033] Figure 4 It is a schematic diagram of the A-A cross-section of the preferred embodiment of the present invention.

[0034] Figure 5 It is a top view schematic diagram of the preferred embodiment of the present invention.

[0035] Figure 6 It is a schematic diagram of the principle of the self-excited oscillation-differential frequency detection circuit of the preferred embodiment of the present invention.

[0036] Figure 7 It is a schematic diagram of the measurement principle of the preferred embodiment of the present invention. Detailed implementation manners

[0037] The following will describe the implementation manners of the present invention in detail with reference to the accompanying drawings and embodiments.

[0038] To improve the measurement accuracy and stability of the existing gas-electric conversion device and achieve precise measurement of geometric dimensions, the present invention provides a MEMS resonant double-chamber gas-electric conversion method and device, which uses a resonator and a pressure-sensitive diaphragm manufactured based on MEMS technology to form a resonant pressure conversion component and a gas conversion component based on a double-chamber structure. The measurement gap s is converted into a differential frequency output in the form of a quasi-digital signal of two or four quartz resonators.

[0039] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 7 shown, the MEMS resonant double-chamber gas-electric conversion method and device of the present invention mainly refer to Figure 1 and Figure 2 ,This method realizes the signal conversion from the measurement gap s to the differential frequency output of the resonant frequencies of two resonators or the differential frequency output Δf of four resonators by means of the gas conversion component 1, the first resonant pressure conversion component 2, and the second resonant pressure conversion component 3.

[0040] Specifically, a structure of the device of the present invention mainly includes a gas conversion component 1, a first resonant pressure conversion component 2, and a second resonant pressure conversion component 3. The gas conversion component 1 adopts a double-chamber structure, including a gas supply chamber 105 and a measurement chamber 106. The gas supply chamber 105 is connected to a gas source through an air inlet joint 101 and is at the same time communicated with the measurement chamber 106. The measurement chamber 106 is connected to a pneumatic measuring head through an air outlet joint 102

[0041] The first resonant pressure conversion component 2 includes a first pressure-sensitive diaphragm 203 and a first working resonator 201. The first pressure-sensitive diaphragm 203 is in direct contact with the gas in the measurement chamber 106 through the first air inlet hole 401, and the first working resonator 201 is arranged on the first pressure-sensitive diaphragm 203.

[0042] Correspondingly, the second resonant pressure conversion component 3 includes a second pressure-sensitive diaphragm 303 and a second working resonator 301. The second pressure-sensitive diaphragm 303 is in direct contact with the gas in the air supply chamber 105 through the second air inlet hole 402, and the second working resonator 301 is arranged on the second pressure-sensitive diaphragm 303.

[0043] When the present invention is applied, compressed gas is first introduced into the air supply chamber 105 and the measurement chamber 106 through the air inlet joint 101. After the gas pressures in the air supply chamber 105 and the measurement chamber 106 are stable, the pneumatic measuring head is used to measure the measurement gap s between the workpiece.

[0044] According to the above structure, when the measurement gap s changes, it first causes the gas pressure P in the measurement chamber 106 x to change, and then causes the first pressure-sensitive diaphragm 203 in direct contact with the measurement chamber 106 to generate a strain d 2 , thereby causing the first working resonator 201 on the first pressure-sensitive diaphragm 203 to change its resonant frequency f 3 due to the change in axial stress. Therefore, the change in the gas pressure P in the measurement chamber 106 x is converted into the resonant frequency f of the first working resonator 201 3 . The signal conversion process of the whole process: measurement gap s → gas pressure P in the measurement chamber 106 x → strain d of the first pressure-sensitive diaphragm 203 2 → resonant frequency f of the first working resonator 201 3 .

[0045] On the other hand, the setting of the air supply chamber 105 can play a role in reducing the error caused by the air source fluctuation during the signal conversion process, and the above goal is achieved through the pressure difference between it and the measurement chamber 106. Specifically, the change in the gas pressure P in the air supply chamber 105 c causes the strain d of the second pressure-sensitive diaphragm 303 in contact with it to change 1 , causing the axial stress inside the second working resonator 301 to change and then causing its resonant frequency f 2 to change. Therefore, the change in the gas pressure P in the air supply chamber 105 c is converted into the resonant frequency f of the second working resonator 301 2 , and the signal conversion process: gas pressure P in the air supply chamber 105c → The second pressure-sensitive diaphragm 303 is strained by d 1 → The resonance frequency f of the second working resonator 301 2 .

[0046] Finally, the measurement gap s is converted into the resonance frequency f of the first working resonator 201 3 and the resonance frequency f of the second working resonator 301 2 The difference, that is, the differential frequency output of the two resonators

[0047] In a further embodiment of the present invention, to compensate for the temperature error, a first compensation resonator 202 is added to the first resonant pressure conversion component 2, and a second compensation resonator 302 is added to the second resonant pressure conversion component 3. In the present invention, the first working resonator 201 is arranged in the working area of the first pressure-sensitive diaphragm 203 to directly characterize the air pressure in the measurement chamber 106, and the first compensation resonator 202 is arranged in the non-working area of the first pressure-sensitive diaphragm 203 to reduce the frequency drift caused by temperature interference through the common-mode rejection principle. Correspondingly, the second working resonator 301 is arranged in the working area of the second pressure-sensitive diaphragm 303 to directly characterize the air pressure in the intake chamber 105, and the second compensation resonator 302 is arranged in the non-working area of the second pressure-sensitive diaphragm 303 to also reduce the frequency drift caused by temperature interference through the common-mode rejection principle

[0048] In this structure, the first compensation resonator 202 compensates for the error of the resonance frequency f of the first working resonator 201 introduced by the ambient temperature based on the common-mode rejection principle. At this time, the change in the gas pressure P in the measurement chamber 106 3 is converted into the frequency difference Δf between the two quartz resonators on the first pressure-sensitive diaphragm 203 x , and the signal conversion process of the whole process: measurement gap s → gas pressure P in the measurement chamber 106 b → the first pressure-sensitive diaphragm 203 is strained by d x → the frequency difference Δf between the first working resonator 201 and the first compensation resonator 202 2 . b .

[0049] On the other hand, the second compensation resonator 302 compensates for the error of the resonance frequency f of the second working resonator 301 introduced by the ambient temperature based on the common-mode rejection principle. At this time, the change in the gas pressure P in the air supply chamber 105 2 is converted into the frequency difference Δf between the two quartz resonators on the second pressure-sensitive diaphragm 303 c , and the signal conversion process: gas pressure P in the air supply chamber 105 a → the second pressure-sensitive diaphragm 303 is strained by d c → the second pressure-sensitive diaphragm 303 is strained by d 1→Frequency difference Δf between the second working resonator 301 and the second compensation resonator 302 a 。

[0050] Finally, the measured gap s is converted into a frequency difference Δf a and Δf b of the differential output Δf, that is, the differential frequency output of the four resonators.

[0051] Therefore, the gas conversion component 1 with a double-chamber structure of the present invention characterizes the change amount of the measured gap s through the gas pressure difference between the air supply chamber 105 and the measurement chamber 106, and can reduce the measurement error caused by the air source fluctuation, and reduce the interference of the air supply pressure fluctuation and the surrounding environment fluctuation on the gas-electricity conversion device. At the same time, the first resonant pressure conversion component 2 and the second resonant pressure conversion component 3 are respectively used to detect the gas pressures in the two chambers, that is, the pressure P x in the measurement chamber 106 of the gas conversion component 1 and the pressure P c in the air supply chamber 105 are converted into the resonant frequency f 3 of the second working resonator 301 and the resonant frequency f 2 of the first working resonator 201, and the measurement error caused by the environmental temperature change can be further reduced by relying on the second compensation resonator 302 and the first compensation resonator 202. Finally, the measurement accuracy and calculation efficiency are improved.

[0052] In the present invention, two resonators are provided on the same resonant pressure conversion component, which respectively act as a working element and a compensation element, and the interference caused by temperature change is weakened based on the common-mode rejection principle. Therefore, the resonant pressure conversion component can convert the gas pressures P x and P c in the two chambers of the gas conversion component into the difference values Δf a and Δf b of the resonant frequencies of the two resonators in the corresponding resonant pressure conversion component respectively.

[0053] In a further embodiment of the present invention, it further includes: a first self-excited oscillation-differential frequency detection circuit 12 and a second self-excited oscillation-differential frequency detection circuit 13.

[0054] The first self-excited oscillation-differential frequency detection circuit 12 is used to generate an excitation signal to make the first working resonator 201 and the first compensation resonator 202 in a resonance state, and can detect the resonant frequency f 3 of the first working resonator 201 and the resonant frequency f 4 of the first compensation resonator 202, and finally output the frequency difference Δf b of the two.

[0055] Accordingly, the second self-excited oscillation-differential frequency detection circuit 13 generates an excitation signal to make the second working resonator 301 and the second compensation resonator 302 work in a resonance state, and can detect the resonance frequency f of the second working resonator 301 2 and the resonance frequency f of the second compensation resonator 302 1 , and finally outputs the frequency difference Δf between the two a .

[0056] In the specific structure of some embodiments, for encapsulation, the pneumoelectric conversion device of the present invention further includes a 304 steel base 4. The first resonance pressure conversion component 2 and the second resonance pressure conversion component 3 are adhesively connected above the 304 steel base 4 through epoxy resin organic glue. The gas conversion component 1 is fixed below the 304 steel base 4 through six M3 bolts 7 to achieve integrated assembly, and the elastic deformation of the O-shaped first sealing ring 8 and the second sealing ring 11 ensures the sealing of different components. In addition, the first air inlet hole 401 and the second air inlet hole 402 are left below the 304 steel base 4 to ensure the direct contact between the gas in the corresponding chamber and the first resonance pressure conversion component 2 and the second resonance pressure conversion component 3

[0057] Furthermore, mainly referring to Figure 4 , the air inlet joint 101 is connected to the gas source and the processing device through a hose, so clean, dry, and stable compressed air can enter the internal chamber of the gas conversion component 1 of the present invention through the air inlet joint 101. The air outlet joint 102 is connected to the pneumatic measuring head through a hose, and the air in the chamber of the gas conversion component 1 can flow into the atmospheric environment through the measuring gap s between the pneumatic measuring head and the workpiece

[0058] The air supply chamber 105 and the measuring chamber 106 are connected through a replaceable throttle hole 108. The air supply chamber 105 is used to stabilize the compressed air entering the gas conversion component 1, and is located between the air inlet joint 1 and the replaceable throttle hole 108 to stabilize the compressed gas entering the pneumoelectric conversion device. The measuring chamber 106 is located between the replaceable throttle hole 108 and the air outlet joint 102. The gas pressure P in this chamber x has a one-to-one corresponding "S"-shaped curve relationship with the measuring gap s, and there is a linear region in this "S"-shaped curve that can be actually measured and applied

[0059] The replaceable orifice 108 included in the gas conversion component 1 of the present invention has external threads and is installed at a specific position in the internal chamber of the gas conversion component 1 in cooperation with the sealing ring 107. Through the sealing ring 107, the pressurized air in the air supply chamber 105 can only flow into the measurement chamber 106 through the internal chamber of the replaceable orifice 108. In addition, a small circular inner hole with a certain depth is machined at the head position of the replaceable orifice 108 to achieve the throttling effect, and a hexagonal inner hole is machined at the end, and different-sized orifices can be replaced by an internal hexagonal wrench to meet the different range and sensitivity adjustment requirements of the gas-electric conversion device of the present invention.

[0060] Since redundant chambers are inevitably generated in the internal chamber of the gas conversion component 1 during the machining process and cannot be isolated from the outside atmosphere, the chamber needs to be sealed by the second sealing plug 103 and the third sealing plug 109. In addition, in order to facilitate the replacement of the replaceable orifice 108 at any time, the present invention is designed with a first sealing plug 104 opposite to it. The first sealing plug 104 has external pipe threads machined on its surface to achieve sealing with the inner wall of the chamber, and a hexagonal inner hole is machined at the end to enable installation and removal by an internal hexagonal wrench. Exemplarily, each sealing plug of the present invention adopts a cylindrical structure, and the internal chamber of the gas conversion component is isolated from the outside and the volume of the redundant chamber is reduced through an interference fit method.

[0061] The first resonant pressure conversion component 2 of the present invention mainly refers to Figure 5 , in addition to the first working resonator 201, the first compensation resonator 202, and the first pressure-sensitive diaphragm 203, it also includes a small signal transfer circuit board 204. The first pressure-sensitive diaphragm 203 is used to convert the gas pressure in the measurement chamber 106 into the deformation of the diaphragm, and the two resonators are used to convert this deformation into the difference in their corresponding resonant frequencies, that is, the frequency difference Δf b .

[0062] Four bosses for facilitating the assembly of the resonators are designed on the upper surface of the first pressure-sensitive diaphragm 203 of the first resonant pressure conversion component 2. A stress concentration groove is machined in the working area of the lower surface and is aligned with the air inlet hole 401 of the 304 steel base 4, and can be connected to the pressurized air P in the measurement chamber 106 xMake direct contact and cause certain deformation, thereby causing the vibrating beam of the first working resonator 201 to be subjected to axial stress and resulting in a frequency offset phenomenon. To improve the temperature interference resistance of the gas-electricity conversion device of the present invention, the first compensation resonator 202 is installed in the non-working area of the first pressure-sensitive diaphragm 203, and the frequency drift caused by temperature interference is reduced through the common-mode rejection principle. The pads on the first working resonator 201 and the first compensation resonator 202 are electrically connected to the small signal transfer circuit 204 through gold wires. The small signal transfer circuit board 204 is provided with an IPEX interface for connecting to an external circuit, which is used to connect the resonator and the external first self-excited oscillation-differential frequency detection circuit 12. In one embodiment, epoxy resin glue is used for adhesion between the first working resonator 201, the first compensation resonator 202, the first pressure-sensitive diaphragm 203 and the small signal transfer circuit board 204 to achieve the assembly of the first resonant pressure conversion component 2.

[0063] Similarly, the second resonant pressure conversion component 3 of the present invention includes a second working resonator 301, a second compensation resonator 302, a pressure-sensitive diaphragm 303 and a small signal transfer circuit board 304. Its structure is the same as or similar to that of the first resonant pressure conversion component 2.

[0064] The resonator adopted in the present invention is a quartz resonator, which is a doubly-clamped tuning fork manufactured based on MEMS technology and operates in its in-plane symmetric reverse vibration mode in combination with surface electrodes. The working resonator of the present invention is used to directly characterize the gas pressure in the air supply / measurement chamber; the compensation resonator compensates for the error caused by the ambient temperature based on the common-mode rejection principle, and further, the differential frequency output Δf a / Δf b characterizes the gas pressure P in the air supply / measurement chamber c / P x .

[0065] Each pressure-sensitive diaphragm of the present invention is a silicon pressure-sensitive diaphragm, which is a strain diaphragm processed by MEMS technology. Four bosses are processed on its upper surface for installing the working and compensation resonators, and the lower surface of the diaphragm corresponding to the working resonator is directly in contact with the gas in the corresponding chamber.

[0066] The self-excited oscillation-differential frequency detection circuit 12 of the gas-electricity conversion device of the present invention, refer to Figure 6, which can generate excitation signals to vibrate the two tuning fork beams of the first working resonator 201 and the first compensation resonator 202 respectively, and has the function of detecting the vibration frequency of the resonant element. Then, the excitation signal is adjusted through the feedback link, and finally the first working resonator 201 and the first compensation resonator 202 are stably operated in their own resonance states, that is, the two tuning fork beams vibrate symmetrically and periodically in opposite directions in the same plane. The self-excited oscillation-differential frequency detection circuit 12 can realize the output frequency f 3 of the first working resonator 201 and the output frequency f 4 of the first compensation resonator 202 for detection and reading. Specifically, it first ensures that the resonator stably oscillates at its fundamental frequency f, then can detect the resonant frequency of the resonator and output a frequency signal, and finally takes the difference between the resonant frequencies of the working and compensation resonators in the differential resonant pressure conversion component to output a differential frequency signal, and finally realizes the output of the frequency difference Δf b of the two resonators through the differential circuit part.

[0067] The working principle of the self-excited oscillation-differential frequency detection circuit 13 of the pneumoelectric conversion device of the present invention is the same as that of the self-excited oscillation-differential frequency detection circuit 12, and can detect the output frequency f 2 of the second working resonator 301 and the output frequency f 1 of the second compensation resonator 302, and finally outputs the frequency difference Δf a of the two resonators. Therefore, the first self-excited oscillation-differential frequency detection circuit 12 and the second self-excited oscillation-differential frequency detection circuit 13 included in the MEMS resonant double-chamber pneumoelectric conversion device of the present invention can convert the measurement gap s into the differential frequency output Δf of the four resonators for detecting the pressures of the air supply chamber 105 and the measurement chamber 106.

[0068] To avoid damage to the first resonant pressure conversion component 2 and the second resonant pressure conversion component 3 caused by human or accidental contact, the present invention respectively provides a first plastic cover 6 and a second plastic cover 5 to protect the first resonant pressure conversion component 2 and the second resonant pressure conversion component 3.

[0069] Refer to Figure 7 , for the working principle of the complete structure of the present invention: the compressed air generated by the air source passes through the air source treatment device and then outputs dry, clean and stable pressurized air. Subsequently, it stabilizes in the air supply chamber 105 of the gas conversion component 1 in the MEMS resonant double-chamber pneumoelectric conversion device of the present invention. Then, when the compressed air flows through the replaceable throttle orifice 108, the flow rate increases and the pressure drops. In the front section of the measurement chamber 106 after the end of the replaceable throttle orifice, the flow rate slows down and the pressure rises. Subsequently, the flow rate and pressure of the compressed air in the remaining section of the measurement chamber 106 are basically stable. Next, it flows through the measuring head and finally flows into the atmospheric environment through the measurement gap s between the measuring head and the surface of the workpiece to be measured. In addition, the size of the measurement gap s directly determines the air pressure value Px , to improve the stability and measurement accuracy in response to gas source fluctuations, the size of the measurement gap s can be converted into the pressure difference ΔP between the air supply chamber 105 and the measurement chamber 106. The air in the air supply chamber 105 and the measurement chamber 106 is in direct contact with the corresponding pressure-sensitive diaphragms 203 / 303, and the pressure-sensitive diaphragms 203 / 303 deform due to air pressurization, ultimately causing the frequency of the working resonators 201 / 301 above the diaphragms to change. The frequency change of the working resonators 201 / 301 can directly characterize the air pressure P in the chamber to be measured. x / P c . To improve the stability and measurement accuracy in response to environmental temperature fluctuations, the pressure in the chamber to be measured is directly converted into the frequency difference Δf between the working resonator 201 / 301 and the compensation resonator 202 / 302 in the corresponding resonant pressure conversion components 2 / 3. a / Δf b . Finally, the size of the measurement gap s is directly converted into the differential frequency output Δf of the four resonators.

[0070] The present invention proposes a brand-new resonant dual-chamber gas-electric conversion method based on MEMS technology, with the output being a quasi-digital frequency signal, eliminating the additional A / D conversion step and the accuracy loss during the conversion process, enhancing the reliability and stability of the output signal, and being beneficial to the performance improvement of the gas-electric conversion device. The present invention provides a novel gas-electric conversion device, whose gas conversion component adopts a dual-chamber structure design, which is beneficial to improving the stability and measurement accuracy of the gas-electric conversion device; a common-mode differential resonant pressure conversion component manufactured based on MEMS technology is adopted, weakening the interference of environmental temperature changes, and being beneficial to reducing the overall size and improving the accuracy.

Claims

1. A MEMS resonant dual-chamber gas-to-electric conversion device, characterized in that: It comprises a gas conversion component (1), a first resonant pressure conversion component (2) and a second resonant pressure conversion component (3); The gas conversion component (1) is a double-chamber structure, comprising a gas supply chamber (105) and a measuring chamber (106) which are connected to each other, the gas supply chamber (105) being connected to a gas source via an air inlet connector (101), and the measuring chamber (106) being connected to a pneumatic measuring head via an air outlet connector (102); The first resonant pressure conversion component (2) comprises a first pressure-sensitive diaphragm (203) and a first working resonator (201) arranged on the first pressure-sensitive diaphragm (203); the first pressure-sensitive diaphragm (203) is connected to the measurement chamber (106) via a first air inlet hole (401); The second resonant pressure conversion component (3) comprises a second pressure-sensitive diaphragm (303) and a second working resonator (301) arranged on the second pressure-sensitive diaphragm (303), and the second pressure-sensitive diaphragm (303) is connected to the air supply chamber (105) via a second air inlet hole (402); The change of the measuring gap s between the pneumatic measuring head and the workpiece is characterized by the difference in the resonant frequency of the first working resonator (201) and the second working resonator (301).

2. The MEMS resonant dual-chamber gas-to-electric conversion device according to claim 1, characterized in that: The first resonant pressure conversion component (2) further comprises: a first compensation resonator (202); the second resonant pressure conversion component (3) further comprises: a second compensation resonator (302); The change in the internal gas pressure of the measuring chamber (106) is converted into a frequency difference Δf between the first working resonator (201) and the first compensation resonator (202). b The change in the internal gas pressure of the gas supply chamber (105) is converted into a frequency difference Δf between the second working resonator (301) and the second compensation resonator (302) a ; The measuring gap s varies by Δf a and Δf b The differential output Δf characterizes.

3. The MEMS resonant dual-chamber gas-to-electric conversion device according to claim 2, characterized in that: The MEMS resonant dual-chamber gas-to-electricity conversion device further comprises: a first self-excited oscillation-differential frequency detection circuit (12) and a second resonant pressure conversion component (3); The first self-excited oscillation-differential frequency detection circuit (12) generates an excitation signal to make the first working resonator (201) and the first compensation resonator (202) work in a resonant state, and detects and outputs a frequency difference Δf between the two resonators. b ; The second self-excited oscillation-differential frequency detection circuit (13) generates an excitation signal to make the second working resonator (301) and the second compensation resonator (302) work in a resonant state, and detects and outputs a frequency difference Δf between the two resonators. a .

4. The MEMS resonant dual-chamber gas-to-electric conversion device according to claim 2 or 3, characterized in that: Each working resonator is installed in the working area of ​​the corresponding pressure-sensitive diaphragm to directly characterize the air pressure in the corresponding chamber; each compensation resonator is installed in the non-working area of ​​the corresponding pressure-sensitive diaphragm to reduce the frequency drift caused by temperature interference through the common mode suppression principle; the working area of ​​each pressure-sensitive diaphragm is processed with a stress concentration groove aligned with the corresponding air inlet hole.

5. The MEMS resonant dual-chamber gas-to-electric conversion device according to claim 2 or 3, characterized in that: Each resonator is a quartz resonator, which is a double-ended fixed tuning fork manufactured based on MEMS technology, and is combined with surface electrodes to work in a symmetrical reverse vibration mode within its surface.

6. The MEMS resonant dual-chamber gas-to-electric conversion device according to claim 2 or 3, characterized in that: Each pressure sensitive diaphragm is a silicon pressure sensitive diaphragm, which is a strain diaphragm manufactured using MEMS technology. Four bosses are processed on its upper surface to install working and compensating resonators, and the lower surface of the diaphragm corresponding to the working resonator is in direct contact with the gas in the corresponding chamber.

7. The MEMS resonant dual-chamber gas-to-electric conversion device according to claim 2 or 3, characterized in that: The air supply chamber (105) is connected to the measuring chamber (106) via a replaceable throttle hole (108); the air supply chamber (105) is provided with a first sealing plug (104), and the first sealing plug (104) is opposite to the disassembly and assembly part of the replaceable throttle hole (108).

8. The MEMS resonant dual-chamber gas-to-electricity conversion device according to claim 2 or 3, characterized in that: The gas pressure P of the measuring chamber (106) x There is an "S"-shaped curve relationship that corresponds one to one with the measurement gap s, and the "S"-shaped curve has a linear region that satisfies actual measurement applications.

9. A MEMS resonant dual-chamber gas-to-electric conversion method, implemented based on the MEMS resonant dual-chamber gas-to-electric conversion device of claim 1, characterized in that: Compressed gas is introduced into the gas supply chamber (105) and the measuring chamber (106) through the gas inlet joint (101), and after the gas pressure in the gas supply chamber (105) and the measuring chamber (106) is stabilized, the measuring gap s between the gas supply chamber (105) and the measuring chamber (106) is measured using a pneumatic measuring head, and the change in the measuring gap s is converted into the gas pressure P in the measuring chamber (106). x The change then causes the first pressure-sensitive membrane (203) in direct contact with the first pressure-sensitive membrane (203) to generate a strain d2, thereby causing the resonance frequency f3 of the first working resonator (201) to change; At the same time, the gas pressure P in the gas supply chamber (105) c The change is converted into a strain d1 of the second pressure sensitive membrane (303), thereby changing the resonance frequency f2 of the second working resonator (301); The change in the measuring gap s between the pneumatic measuring head and the workpiece is characterized by the difference between f3 and f2.

10. A MEMS resonant dual-chamber gas-to-electric conversion method, implemented based on a MEMS resonant dual-chamber gas-to-electric conversion device according to claim 2, characterized in that: Compressed gas is introduced into the gas supply chamber (105) and the measuring chamber (106) through the gas inlet joint (101), and after the gas pressure in the gas supply chamber (105) and the measuring chamber (106) is stabilized, a pneumatic measuring head is used to measure the measuring gap s between the gas supply chamber (105) and the measuring chamber (106); The change in the measuring gap s is converted into the gas pressure P in the measuring chamber (106) x The change of the first pressure sensitive membrane (203) in direct contact with the first pressure sensitive membrane (203) causes a strain d2, thereby changing the resonance frequency f3 of the first working resonator (201). At the same time, the first compensation resonator (202) compensates for the error caused by the ambient temperature based on the common mode suppression principle. x The change is converted into the frequency difference Δf between the two resonators b ; At the same time, the gas pressure P in the gas supply chamber (105) c The change is converted into the strain d1 of the second pressure sensitive diaphragm (303), thereby changing the resonance frequency f2 of the second working resonator (301). At the same time, the second compensation resonator (302) compensates for the error caused by the ambient temperature based on the common mode suppression principle. c The change is converted into a frequency difference Δf between the second working resonator (301) and the second compensation resonator (302) a ; The measuring gap s between the pneumatic measuring head and the workpiece changes by Δf a and Δf b The differential output Δf characterizes.

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