A micro differential pressure sensor with calibration and method of manufacture

Abstract

The present application relates to the technical field of micro pressure difference sensor, and provides a micro pressure difference sensor with calibration and a manufacturing method thereof, which comprises a shell, an internal cavity is arranged in the shell, and the measured medium is input through a pagoda nozzle at the bottom end of the shell; wherein the internal cavity comprises a low-pressure cavity and a high-pressure cavity, and the low-pressure cavity and the high-pressure cavity are isolated by a center diaphragm; one side of the internal cavity is mounted on a circuit board, a piezoresistive pressure sensor chip and an array-arranged thin film resistor are arranged on the circuit board, and the circuit board is externally connected through an electrical interface at the bottom of the shell; the thin film resistor is electrically connected with the piezoresistive pressure sensor chip, is arranged in the internal cavity, and is connected with a first pressure-sensitive element in the low-pressure cavity and a second pressure-sensitive element in the high-pressure cavity respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of micro differential pressure sensors, and in particular to a micro differential pressure sensor with calibration function and a manufacturing method thereof. Background Art

[0002] A differential pressure sensor is a sensor used to measure the tiny difference between two pressures. It is widely used in many fields, such as HVAC systems, medical equipment, filtration systems, and various industrial process controls.

[0003] Micro differential pressure sensors play a vital role in modern industry and scientific research. They are widely used in various applications requiring precise measurement of tiny pressure differences. However, the measurement accuracy of micro differential pressure sensors can be affected by environmental factors, wear caused by long-term use, and manufacturing process limitations.

[0004] Therefore, the micro differential pressure sensor cannot achieve automatic calibration and the measurement is inaccurate. Summary of the Invention

[0005] The present invention provides a micro differential pressure sensor with calibration function and a manufacturing method thereof, which are used to solve the problem that the micro differential pressure sensor cannot realize automatic calibration and the measurement is inaccurate.

[0006] The present invention proposes a micro differential pressure sensor with calibration, comprising:

[0007] The shell has a cavity portion inside, and the cavity portion inputs the measured medium through the pagoda nozzle at the bottom of the shell; wherein the cavity portion includes a low-pressure cavity and a high-pressure cavity, and the low-pressure cavity and the high-pressure cavity are separated by a central diaphragm;

[0008] One side of the cavity is mounted on a circuit board, on which a piezoresistive pressure sensor chip and an array of thin-film resistors are arranged. The circuit board is connected to the outside through an electrical interface at the bottom of the housing.

[0009] The thin film resistor is electrically connected to the piezoresistive pressure sensor chip, is arranged in the cavity portion, and is respectively connected to the first pressure sensitive element in the low-pressure cavity and the second pressure sensitive element in the high-pressure cavity.

[0010] Preferably, a mesh shielding layer is arranged between the circuit board and the housing, wherein the mesh shielding layer is formed by applying ink and conductive material through preset mesh holes on the inner side of the housing.

[0011] Preferably, a signal conditioning circuit is configured on the circuit board;

[0012] Among them, the signal conditioning circuit includes: a charge amplifier circuit connected to the first pressure-sensitive element and the second pressure-sensitive element, the charge amplifier circuit is connected in sequence to the trap circuit, the low-pass filter circuit, the level shift circuit, the ADC sampler and the pressure difference signal output device, and a negative power supply circuit is also configured between the charge amplifier circuit and the level shift circuit.

[0013] Preferably, the charge amplification circuit includes a first charge sensor and a second charge sensor;

[0014] Wherein, the input end of the first charge sensor is connected to the first pressure sensitive element, and the output end of the first charge sensor is connected to the first charge amplification circuit;

[0015] An input end of the second charge sensor is connected to the second pressure sensitive element, and an output end of the second charge sensor is connected to the second charge amplification circuit;

[0016] The first charge amplifier circuit and the second charge amplifier circuit are connected to the trap circuit via a first differential amplifier.

[0017] Preferably, the trap circuit includes an LC matching device, an active band-stop filter and a digital potentiometer; wherein the input end of the active band-stop filter is connected to the LC matching device and the digital potentiometer respectively, and the input end of the digital potentiometer is connected to the LC matching device;

[0018] The LC matching device is used to connect the output end of the charge discharge circuit and determine the amplified signal of the preset frequency;

[0019] The digital potentiometer is used to adjust the center frequency of the active band-stop filter.

[0020] Preferably, the level shift circuit includes a clamping terminal and a displacement detection circuit connected to the clamping terminal, the displacement detection circuit is connected to the output terminal of the trap circuit, and the output terminal of the displacement detection circuit is connected to the low-drift comparator; wherein the level shift detection circuit includes a first coupling terminal and a second coupling terminal;

[0021] The first coupling end is connected to the clamping end, and the reference potential square wave is set through the clamping end;

[0022] The second coupling end is connected to the output end of the displacement detection circuit and outputs a real-time potential curve;

[0023] The low drift comparator is used to compare the potential square wave with the real-time potential curve to determine the level shift.

[0024] Preferably, the thin film resistors arranged in the array output pressure sensing signals through the following steps:

[0025] Step 1: constructing a high-frequency superposition-based resistance distribution grid; wherein the resistance distribution grid can be built by taking any one grid as a high-frequency origin, and a high-frequency superposition resistance value model is built;

[0026] Step 2: determining the resistance value interval of the low-pressure cavity and the high-pressure cavity based on the resistance distribution grid;

[0027] Step 3: when at least one grid in the low-pressure cavity and at least one grid in the high-pressure cavity are triggered, inputting the corresponding grid area into the high-frequency superposition resistance value model to determine the first redundant signal of the low-pressure cavity and the second redundant signal of the high-pressure cavity;

[0028] Step 4: judging whether the first redundant signal and the second redundant signal satisfy the pressure difference comparison condition;

[0029] Step 5: when the pressure difference comparison condition is satisfied, outputting the pressure sensing signal.

[0030] Preferably, the low-pressure cavity is determined by the following steps of modeling:

[0031] Pre-setting a low-pressure pressure difference range and setting a plurality of stress points, and constructing a first modeling model of the low-pressure cavity through the stress points;

[0032] According to the low-pressure pressure difference range and the strain function of the low-pressure space, the deformation parameters under different low-pressure pressure differences are determined, and a geometric deformation model is constructed;

[0033] According to the geometric deformation model and the first modeling model, a second modeling model of the low-pressure cavity is generated under different pressure conditions;

[0034] Based on the pressure difference deformation response, a pressure simulation analysis model of the low-pressure cavity is established, and the first geometric parameter of the low-pressure cavity is determined.

[0035] Preferably, the high-pressure cavity is determined by the following steps of modeling:

[0036] Pre-setting the electric field intensity of the high-pressure cavity;

[0037] According to the electric field intensity, a dynamic three-dimensional magnetic field transformation model is built;

[0038] According to the three-dimensional magnetic field transformation model, the second geometric parameter of the high-pressure cavity is determined.

[0039] In a second aspect, the application provides a manufacturing method of a calibrated micro-pressure difference sensor, for manufacturing the calibrated micro-pressure difference sensor, comprising:

[0040] Providing a shell;

[0041] Providing a circuit board with a mesh shielding layer inside the shell;

[0042] Determine the first geometric parameter of the low-pressure cavity inside the shell based on the preset low-pressure differential range.

[0043] Determine the second geometric parameter of the high-pressure cavity inside the shell based on the preset electric field intensity.

[0044] According to the first geometric parameter and the second geometric parameter, a cavity part is machined inside the shell and embedded with the side of the film resistor of the circuit board.

[0045] A pressure-sensitive element is arranged in the cavity part, and after the pressure-sensitive element is arranged, an electrical interface is arranged at the bottom of the shell to be connected with the circuit board, and a spire nozzle is arranged to input the measured medium.

[0046] The beneficial effects of the present application are:

[0047] By adopting the piezoresistive pressure sensor chip and the film resistor array, the sensor can realize high-precision pressure measurement, meet the strict industrial standards. The sensor has a built-in calibration function, which can be quickly calibrated on site, improving the accuracy and reliability of the measurement. By mounting the sensor on the circuit board and using the internal structure of the shell to isolate the low-pressure and high-pressure cavities, the compactness of the structure is realized, which is convenient for installation and use in various environments. The design takes into account the influence of different media and temperature, so that the sensor can work stably in various environments. Through the external electrical interface, the maintenance and replacement of the sensor become more convenient.

[0048] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the present application can be achieved and obtained by the structure particularly pointed out in the written description and the accompanying drawings.

[0049] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0050] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation of the present application.

[0051] In the drawings:

[0052] Figure 1 The internal circuit composition diagram of a micro-pressure difference sensor with calibration in the embodiment of the present application;

[0053] Figure 2 The signal conditioning circuit diagram of a micro-pressure difference sensor with calibration in the embodiment of the present application;

[0054] Figure 3A notch filter circuit diagram in the embodiment of the present application;

[0055] Figure 4 A pressure sensing signal output process diagram in the embodiment of the present application;

[0056] Figure 5 A method flow chart of a manufacturing method of a micro differential pressure sensor with calibration in the embodiment of the present application;

[0057] Figure 6 An external structure diagram of a micro differential pressure sensor with calibration in the embodiment of the present application. DETAILED DESCRIPTION

[0058] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to explain and illustrate the present application, and are not used to limit the present application.

[0059] Embodiment 1:

[0060] As shown in FIGS. Figure 1 and Figure 6 The present embodiment provides a micro differential pressure sensor with calibration, comprising:

[0061] A shell 1, which is internally provided with a cavity part, the cavity part inputs the measured medium through a pagoda nozzle 3 at the bottom end of the shell 1; wherein the cavity part includes a low-pressure cavity and a high-pressure cavity, and the low-pressure cavity and the high-pressure cavity are isolated by a center diaphragm;

[0062] In the present application, the shell 1 is used to provide a containing space, the cavity part inputs the medium through the pagoda nozzle 3 to realize the measurement of differential pressure, the pagoda nozzle 3 is two symmetrically arranged first and second pagoda nozzles, the first pagoda nozzle is connected to the low-pressure cavity in communication; the second pagoda nozzle is connected to the high-pressure cavity in communication; the first pagoda nozzle is connected to the low-pressure cavity in communication when it is connected to the low pressure; the second pagoda nozzle is connected to the high-pressure cavity in communication when it is connected to the high pressure. In the present application, the center diaphragm is arranged to realize the isolation of the two, and in actual implementation, a liquid-filled isolation diaphragm can also be arranged. The low-pressure cavity and the high-pressure cavity are isolated by the center diaphragm in the present application, which can effectively prevent the mutual interference of the measured medium and improve the measurement accuracy of the sensor.

[0063] The cavity part is mounted on a circuit board on one side, the circuit board is provided with a piezoresistive pressure sensor chip and an array of thin film resistors, and the circuit board is externally connected through an electrical interface 2 at the bottom of the shell 1;

[0064] In the application, one side of the cavity part is fixed on the circuit board to realize electrical connection and perform measurement. In the application, the core technology adopts a piezoresistive pressure sensor chip. In the implementation process, the sensing signal on the center diaphragm is converted into resistance change, mainly the slight deformation of the center diaphragm under different pressure differences. The conversion into resistance change, and the array-arranged thin film resistor provide a calibrated reference for the resistance change, realizing compensation of non-linear error and temperature drift.

[0065] The thin film resistor is electrically connected with the piezoresistive pressure sensor chip, arranged in the cavity part, and connected with the first pressure-sensitive element in the low-pressure cavity and the second pressure-sensitive element in the high-pressure cavity respectively. The first pressure-sensitive element and the second pressure-sensitive element are connected with the thin film resistor, and the first pressure-sensitive element and the second pressure-sensitive element have the same effect as the center diaphragm, which is also to realize collection of pressure difference, and through the array-arranged thin film resistor, a calibrated reference is provided for the resistance change, realizing compensation of non-linear error and temperature drift. The piezoresistive pressure sensor chip is a kind of independent sensing signal calculation and processing chip.

[0066] Through synchronous collection and double monitoring, the final detection result is obtained, and is output through the electrical interface 2 to realize interaction with the outside.

[0067] The core of the application technology is the setting of the thin film resistor and the piezoresistive pressure sensor chip, which can solve the problems of non-linearity, temperature drift and zero point drift in the micro pressure difference scene. The thin film resistor can also realize multi-point sampling compensation in actual use, realize compensation under spatial temperature gradient, and solve the problem of non-linear compensation. By directly connecting two pressure-sensitive elements, common mode error is eliminated, and the problems of temperature drift and zero point drift are solved. The thin film resistor can compensate the pressure change of the measured medium, and can also improve the response speed and sensitivity of the differential pressure sensor.

[0068] In the calibration operation:

[0069] The sensor is internally provided with a thin film resistor and a piezoresistive pressure sensor chip for realizing built-in calibration. The thin film resistor array is used to compensate the influence of temperature change and other factors on the measurement accuracy.

[0070] In the specific implementation:

[0071] First step: input standard pressure medium through the pagoda nozzle 3 at the bottom end of the shell 1 to apply a known pressure difference to the low-pressure cavity and the high-pressure cavity.

[0072] Second step: the sensor detects and converts the pressure difference into an electrical signal through the internal pressure-sensitive elements, i.e. the first pressure-sensitive element and the second pressure-sensitive element.

[0073] Step 3: The electrical signal is transmitted to the piezoresistive pressure sensor chip through the thin film resistor. The piezoresistive pressure sensor chip compares the difference between the actual output signal and the standard signal.

[0074] Step 4: Based on these differences, the calibration algorithm of the piezoresistive pressure sensor chip adjusts the signal output to eliminate the deviation and ensure the accuracy of the measurement results.

[0075] In addition to built-in calibration, the sensor can also be connected to an external calibration device through the electrical interface 2 at the bottom of the housing 1 for more precise calibration. However, this requires the use of specialized calibration software and instruments, such as a gas spectrometer.

[0076] In terms of technical effects, this application uses a piezoresistive pressure sensor chip and a thin-film resistor array to achieve high-precision pressure measurement that meets stringent industrial standards. The sensor has a built-in calibration function, which allows for rapid on-site calibration to improve measurement accuracy and reliability. By mounting the sensor on a circuit board and using the internal structure of the housing 1 to isolate the low-pressure and high-pressure cavities, a compact structure is achieved, making it easy to install and use in various environments. The design takes into account the effects of different media and temperatures, enabling the sensor to operate stably in a variety of environments and be calibrated based on different working environments. Through the external electrical interface 2, the maintenance and replacement of the sensor becomes more convenient.

[0077] Example 2:

[0078] A mesh shielding layer is arranged between the circuit board and the housing 1 , wherein the mesh shielding layer is formed by applying ink and conductive material through preset mesh holes on the inner side of the housing 1 .

[0079] The mesh shielding layer of the present application is used to suppress electromagnetic interference. For example: external electromagnetic waves, stray currents. The mesh structure allows the shielding layer to be integrated with the shell 1. Unlike the traditional split shielding cover, there will be no large gaps. Relatively speaking, it is formed by brushing with preset mesh holes, and the mesh holes can be used as ink penetration channels. The mesh shielding layer is integrated with the shell 1 to form a dual composite structure of mechanical and electrical, achieving high-frequency suppression, and the shielding layer will not be separated due to time factors.

[0080] Example 3:

[0081] like Figure 2 As shown, the circuit board of the present application is configured with a signal conditioning circuit;

[0082] The signal conditioning circuit comprises a charge amplification circuit connected with the first pressure-sensitive element and the second pressure-sensitive element, the charge amplification circuit is sequentially connected with a wave trap circuit, a low-pass filter circuit, a level shift circuit, an ADC sampler and a differential pressure signal output device, and a negative power supply circuit is further arranged between the charge amplification circuit and the level shift circuit.

[0083] In the application, the charge amplification circuit is used to convert the high-impedance charge signal of the pressure-sensitive element into a low-impedance voltage signal, suppress transmission loss and solve micro-pressure signal attenuation.

[0084] Then, the power frequency interference is filtered out through the wave trap circuit in series.

[0085] The high-frequency noise is cut off through the low-pass filter circuit in series, and the frequency band of the effective differential pressure signal is reserved.

[0086] The negative pressure signal is lifted to the positive voltage range that can be sampled by the ADC sampler through the level shift circuit in series, and the sampling accuracy is improved.

[0087] The signal digital simulation is realized through the ADC sampler in series, and finally the output signal of the standard format is output through the differential pressure signal output device. The negative power supply circuit provides a negative voltage reference for the level shift circuit, so that accurate measurement is realized in the full range.

[0088] In the application, the charge amplification circuit is sequentially connected with the wave trap circuit, the low-pass filter circuit, the level shift circuit, the ADC sampler and the differential pressure signal output device, to form a cascaded signal processing sequence. The signal is first amplified by the charge amplification circuit, and then filtered to ensure the integrity of the signal. The traditional level shift circuit should be before the ADC, but the charge amplification output of the application contains a negative pressure signal, which needs to be level shifted before filtering, otherwise the filter circuit may not be able to handle negative voltage. The negative power supply circuit in the application digitizes the full range of the negative pressure signal, which also ensures the integrity of the signal.

[0089] Embodiment 4:

[0090] The charge amplification circuit of the application comprises a first charge sensor and a second charge sensor. Two charge sensors are used in the application to independently convert the charge signals of the high / low pressure chambers and prevent signal crosstalk. The input end of the first charge sensor is connected with the first pressure-sensitive element, and the output end of the first charge sensor is connected with the first charge amplification circuit, so as to accurately collect the micro-charge signals of the low pressure chamber.

[0091] The input end of the second charge sensor is connected with the second pressure-sensitive element, and the output end of the second charge sensor is connected with the second charge amplification circuit, so as to accurately collect the micro-charge signals of the high pressure chamber.

[0092] The first charge amplification circuit and the second charge amplification circuit are connected with the wave trap circuit through the first differential amplifier.

[0093] In the present application, the first charge amplifier circuit and the second charge amplifier circuit can respectively amplify the dual-channel signals during measurement, retaining the original phase information. At the same time, by connecting the notch circuit through the first differential amplifier, the dual-channel amplified signals can be subjected to common-mode suppression and the power frequency interference can be filtered out.

[0094] In actual implementation, a differential amplifier is used to connect the first charge amplifier circuit and the second charge amplifier circuit to eliminate common-mode interference in the circuit. The first charge sensor and the second charge sensor are connected to the two charge amplifier circuits respectively. The working states of the two sensors are independent of each other, avoiding interference introduced by problems of the sensors themselves, and can also output signals of specific frequencies. In this application, the sensor and the charge amplifier circuit are directly connected to form an impedance matching chain, without the need for long wires that cause capacitive interference, and can achieve independent amplification and common-mode suppression.

[0095] Example 5:

[0096] like Figure 3 As shown, the notch circuit of the present application includes an LC matcher, an active band-stop filter, and a digital potentiometer. The input of the active band-stop filter is connected to the LC matcher and the digital potentiometer, respectively, and the input of the digital potentiometer is connected to the LC matcher. The LC matcher of the present application is used to match the output impedance of the charge amplifier circuit, preset the signal gain at the target frequency, and solve the signal attenuation problem caused by impedance mismatch. The active band-stop filter deeply suppresses interference at the target frequency. The digital potentiometer can dynamically adjust the center frequency of the filter, expanding its application scenarios.

[0097] In this application, the frequency selection of the LC matcher and the dynamic adjustment of the center frequency of the filter by the digital potentiometer are combined to achieve impedance matching and frequency preselection at the same time, and simultaneously improve the interference suppression capability and frequency adaptability, so that the LC matcher pre-enhances the target frequency signal, and the filter always operates in the optimal suppression range.

[0098] Example 6:

[0099] The level shift circuit of the present application includes a clamping terminal and a displacement detection circuit connected to the clamping terminal, the displacement detection circuit is connected to the output terminal of the trap circuit, and the output terminal of the displacement detection circuit is connected to the low-drift comparator; wherein the level shift detection circuit includes a first coupling terminal and a second coupling terminal;

[0100] The first coupling end is connected to the clamping end, and a reference potential square wave is set through the clamping end; the level shift circuit of the present application sets a reference potential square wave through the clamping end. The potential square wave is the standard for subsequent potential curve comparison and is a stable voltage waveform to ensure the accuracy of the level shift.

[0101] The second coupling end is connected with the output end of the displacement detection circuit and outputs a real-time potential curve;

[0102] The low-drift comparator is used for comparing the potential square wave and the real-time potential curve to determine the level displacement amount.

[0103] The displacement detection circuit of the application is responsible for real-time monitoring and recording the dynamic change of the potential curve, and through the output end of the displacement detection circuit, a real-time potential curve is obtained, which is used for displaying the real state of the sensor in the working process and obtaining real-time sensor state data.

[0104] The low-drift comparator is responsible for comparing the potential square wave and the real-time potential curve to determine the value of the level displacement. Through the comparison result, the current state of the sensor is obtained, and the sensor can be calibrated and corrected as needed.

[0105] The displacement monitoring circuit is used as an intermediary, the first coupling end is used as a transmission ideal reference square wave, the reference wave band with time domain jump characteristics exists, the second coupling end is used for extracting the real-time signal superimposed with the displacement amount, and the comparator compares the difference between the time domain waveforms of the two to determine whether there is signal distortion, so as to correct the level displacement. In implementation, the steep edge of the provided square wave reference provides high-precision time domain positioning, can track signal distortion in real time, and the time domain waveform difference is calculated based on a specific phase difference threshold or amplitude tolerance.

[0106] Embodiment 7:

[0107] As shown in Figure 4 , the array-arranged thin-film resistor outputs a pressure sensing signal through the following steps:

[0108] Step 1: Construct a resistance distribution grid based on high-frequency superposition; wherein the resistance distribution grid can be built as a high-frequency origin by any one grid to build a high-frequency superposition resistance value model; the high-frequency superposition resistance value model of the application is combined with a Wheatstone bridge to build.

[0109] The above step 1 builds a high-frequency superposition resistance value model by constructing a resistance distribution grid based on high-frequency superposition, which is realized by taking any one grid as a high-frequency origin. The core effect is to build a dynamic resistance network model, which supports any grid as a reference point.

[0110] Step 2: Determine the resistance value interval of the low-pressure cavity and the high-pressure cavity based on the resistance distribution grid;

[0111] The above step 2 divides the pressure sensitive area by determining the resistance value interval, and more accurately isolates the double-cavity signal interference.

[0112] Step 3: When at least one grid in the low-pressure cavity and at least one grid in the high-pressure cavity are triggered, the corresponding grid area is input into the high-frequency superposition resistance model to determine the first redundant signal of the low-pressure cavity and the second redundant signal of the high-pressure cavity;

[0113] The grid trigger mechanism in step 3 above can respond to local pressure changes, reducing power consumption and load. By superimposing a resistance model at high frequency, that is, analyzing the grid resistance changes through high-frequency excitation, the signal-to-noise ratio is improved, and the final calculated redundant signal is determined.

[0114] Step 4: Determine whether the first redundant signal and the second redundant signal meet the pressure difference comparison condition; identify abnormal data through dual-channel cross-validation, and then prevent false triggering through dynamic preset judgment.

[0115] Step 5: When the pressure difference comparison condition is met, the pressure sensing signal is output.

[0116] In this application, any grid is used as the high-frequency origin, and the origin is dynamically selected based on the pressure distribution hotspot, thus realizing an adaptive superposition model and achieving partitioned detection. By triggering and generating redundant signals by at least one grid in each of the two cavities, cross-validation is achieved to prevent local resistance aging and other conditions that may lead to incorrect judgment results. In this application, the redundant signal comparison mechanism can automatically block abnormal grid data.

[0117] Example 8:

[0118] The low-pressure cavity modeling steps of this application are as follows:

[0119] First, a low-pressure differential range is set, and multiple stress points are set, and a first modeling model of the low-pressure cavity is constructed through the stress points; setting multiple stress points can determine the boundary of the low-pressure pressure, and through the first modeling model, pressure and stress mapping can be achieved, and local pressure signals can be quantified.

[0120] Based on the low-pressure differential range and the strain function of the low-pressure space, deformation parameters under different low-pressure differentials are determined, and a geometric deformation model is constructed. The deformation parameters obtained through the strain function in this application can be used to correlate material deformation and pressure. Through structural changes, the size and shape of the low-pressure cavity under different stress states can be clarified and refined, and the pressure detection results can be determined. The strain function reflects the geometric spatial changes of the low-pressure cavity under different pressures and determines the deformation parameters.

[0121] According to the geometric deformation model and the first modeling model, a second modeling model of the low-pressure cavity is generated under different pressure conditions; the second modeling model and the geometric deformation model combined therewith can determine the spatial changes in the cavity, that is, the changes in the spatial structure of the cavity under the change of the central diaphragm. Then, based on the collaboration of the two models, the static changes and dynamic deformations of the cavity are integrated. Based on the pressure difference deformation response, a pressure simulation analysis model of the low-pressure cavity is established, and the first geometric parameters of the low-pressure cavity are determined. This application simulates the cavity performance under real working conditions through pressure simulation, generates a pressure simulation model, and determines the geometric parameters corresponding to the final geometric structure of the low-pressure cavity.

[0122] The stress point model of the present application outputs local stress extremes, which can correct the material nonlinear parameters of the geometric deformation model, that is, the nonlinear parameters of the cavity change; the geometric deformation model feeds back the pre-deformation amount to iteratively update the stress point distribution, thereby compensating for the additional deformation of the stress concentration area through the collaboration of the two models, and when determining the final geometric structure of the low-pressure cavity, the errors in the deformation can be eliminated and the accuracy can be improved.

[0123] Example 9:

[0124] The high-pressure cavity of this application includes the following steps to model and determine:

[0125] The electric field strength of the high-voltage cavity is pre-set. In this application, the electric field strength is set to determine the electromagnetic boundary, thereby realizing magnetic field modeling;

[0126] According to the electric field strength, a dynamic three-dimensional magnetic field transformation model is built; the three-dimensional magnetic field transformation model can simulate the electromagnetic field distribution of the high-voltage cavity, predict the interference source, and thus reduce interference;

[0127] According to the three-dimensional magnetic field transformation model, the second geometric parameters of the high-voltage cavity are determined. Through the second geometric parameters, electromagnetic interference can be more strongly suppressed by optimizing the cavity structure.

[0128] The consideration of the electric field strength in this application is to ensure the normal operation of the sensor. The three-dimensional magnetic field transformation model is implemented through mathematical modeling or computer simulation to determine the law of magnetic field changes inside the high-voltage cavity. Through comparative experiments or numerical calculations, the geometric parameters of the high-voltage cavity under different magnetic field environments are obtained to ensure the efficient operation of the sensor. Because this application uses magnetic field modeling, it can disperse the charge accumulation in the ionization area by deploying an ellipsoidal cavity and cut off the source of magnetic field interference.

[0129] Example 10:

[0130] like Figure 5 As shown, the present application also proposes a method for manufacturing a calibrated micro differential pressure sensor, comprising:

[0131] Providing a housing 1;

[0132] A circuit board with a mesh shielding layer is provided inside the housing 1;

[0133] Determining first geometric parameters of the low-pressure cavity inside the housing 1 based on a preset low-pressure differential range;

[0134] Determining a second geometric parameter of the high-voltage cavity inside the housing 1 based on a preset electric field strength;

[0135] According to the first geometric parameter and the second geometric parameter, a cavity is processed inside the housing 1 and is embedded with a side of the circuit board where the thin film resistor is present, so that the thin film resistor is in physical contact with the cavity.

[0136] A pressure-sensitive element is arranged in the cavity, and after the pressure-sensitive element is arranged, an electrical interface 2 connected to the circuit board and a pagoda nozzle 3 for inputting the measured medium are respectively arranged on the bottom of the shell 1.

[0137] This application provides a housing 1 to establish the basic structure of the sensor, which must possess sufficient mechanical strength and stability to withstand all operating conditions. A circuit board with a mesh shielding layer is placed within the housing 1. This mesh shielding layer effectively protects the circuit board from external electromagnetic interference, improving the accuracy and reliability of the sensor. First geometric parameters of the low-pressure cavity within the housing 1 are determined based on a preset low-pressure differential range. This parameter adjustment is performed to ensure the sensor operates properly in a specific low-pressure environment. Second geometric parameters of the high-pressure cavity within the housing 1 are determined based on a preset electric field strength. This parameter adjustment is performed to ensure the sensor operates properly in a specific electric field environment. Based on the first and second geometric parameters, a cavity is machined within the housing 1 and interlocked with the side of the circuit board containing the thin-film resistor. All components are assembled to form the physical structure of the sensor. A pressure-sensitive element is placed within the cavity. After the pressure-sensitive element is placed, an electrical interface 2 for connecting to the circuit board and a pagoda nozzle 3 for inputting the measured medium are provided on the bottom of the housing 1. This allows the sensor to connect to the external circuit and begin actual operation.

[0138] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A micro differential pressure sensor with calibration, characterized in that: include: A housing (1) is provided with a cavity portion therein, wherein the cavity portion inputs a measured medium through a pagoda nozzle (3) at the bottom end of the housing (1); wherein the cavity portion includes a low-pressure cavity and a high-pressure cavity, and the low-pressure cavity and the high-pressure cavity are separated by a central diaphragm; wherein the central diaphragm is used to generate a resistance change signal at different pressure differences; One side of the cavity portion is mounted on a circuit board, on which a piezoresistive pressure sensor chip and an array of thin-film resistors are arranged, and the circuit board is externally connected via an electrical interface (2) at the bottom of the housing (1); The thin film resistors arranged in the array output pressure sensing signals through the following steps: Step 1: Construct a resistance distribution grid based on high-frequency superposition. The resistance distribution grid can use any grid as the high-frequency origin to build a high-frequency superposition resistance model. Step 2: Based on the resistance distribution grid, determine the resistance range of the low-voltage cavity and the high-voltage cavity; Step 3: When at least one grid in the low-pressure cavity and at least one grid in the high-pressure cavity are triggered, the corresponding grid area is input into the high-frequency superposition resistance model to determine the first redundant signal of the low-pressure cavity and the second redundant signal of the high-pressure cavity; Step 4: Determine whether the first redundant signal and the second redundant signal meet the pressure difference comparison condition; Step 5: When the pressure difference comparison condition is met, the pressure sensing signal is output; The thin film resistor is electrically connected to the piezoresistive pressure sensor chip, is disposed within the cavity, and is respectively connected to the first pressure-sensitive element in the low-pressure cavity and the second pressure-sensitive element in the high-pressure cavity; wherein the thin film resistor is used to provide a calibration reference for the resistance change signal; The low-pressure cavity is modeled and determined by the following steps: Presetting a low-pressure differential range and setting a plurality of stress points, and constructing a first modeling model of the low-pressure cavity through the stress points; According to the low-pressure differential range and the strain function of the low-pressure space, the deformation parameters under different low-pressure differentials are determined, and a geometric deformation model is constructed; generating a second modeling model of the low-pressure cavity under different pressure conditions according to the geometric deformation model and the first modeling model; Establishing a pressure simulation analysis model of the low-pressure cavity based on the pressure differential deformation response, and determining the first geometric parameters of the low-pressure cavity; The high pressure cavity is modeled and determined by the following steps: Presetting the electric field strength of the high-voltage cavity; Build a dynamic three-dimensional magnetic field transformation model based on the electric field strength; The second geometric parameter of the high-pressure cavity is determined according to the three-dimensional magnetic field transformation model.

2. A calibrated micro differential pressure sensor according to claim 1, characterized in that: A mesh shielding layer is arranged between the circuit board and the housing (1), wherein the mesh shielding layer is formed by applying ink and conductive material through preset mesh holes on the inner side of the housing (1).

3. A calibrated micro differential pressure sensor according to claim 1, characterized in that: The circuit board is provided with a signal conditioning circuit; Among them, the signal conditioning circuit includes: a charge amplifier circuit connected to the first pressure-sensitive element and the second pressure-sensitive element, the charge amplifier circuit is connected in sequence to the trap circuit, the low-pass filter circuit, the level shift circuit, the ADC sampler and the pressure difference signal output device, and a negative power supply circuit is also configured between the charge amplifier circuit and the level shift circuit.

4. A calibrated micro differential pressure sensor according to claim 3, characterized in that: The charge amplification circuit includes a first charge sensor and a second charge sensor; Wherein, the input end of the first charge sensor is connected to the first pressure sensitive element, and the output end of the first charge sensor is connected to the first charge amplification circuit; An input end of the second charge sensor is connected to the second pressure sensitive element, and an output end of the second charge sensor is connected to the second charge amplification circuit; The first charge amplifier circuit and the second charge amplifier circuit are connected to the trap circuit via a first differential amplifier.

5. The calibrated micro differential pressure sensor according to claim 3, characterized in that: The trap circuit includes an LC matching device, an active band-stop filter and a digital potentiometer; wherein the input end of the active band-stop filter is connected to the LC matching device and the digital potentiometer respectively, and the input end of the digital potentiometer is connected to the LC matching device; The LC matching device is used to connect to the output end of the charge amplifier circuit and determine the amplified signal of the preset frequency; The digital potentiometer is used to adjust the center frequency of the active band-stop filter.

6. A calibrated micro differential pressure sensor according to claim 3, characterized in that: The level shift circuit includes a clamping terminal and a displacement detection circuit connected to the clamping terminal, the displacement detection circuit is connected to the output terminal of the trap circuit, and the output terminal of the displacement detection circuit is connected to the low-drift comparator; wherein the level shift detection circuit includes a first coupling terminal and a second coupling terminal; The first coupling end is connected to the clamping end, and the reference potential square wave is set through the clamping end; The second coupling end is connected to the output end of the displacement detection circuit and outputs a real-time potential curve; The low drift comparator is used to compare the potential square wave with the real-time potential curve to determine the level shift.

7. A method for manufacturing a micro differential pressure sensor with calibration, used to manufacture the micro differential pressure sensor with calibration according to any one of claims 1 to 6, characterized in that: include: Providing a housing (1); A circuit board with a mesh shielding layer is arranged inside the housing (1); Determining first geometric parameters of the low-pressure cavity inside the housing (1) based on a preset low-pressure differential range; Determining a second geometric parameter of the high-voltage cavity inside the housing (1) based on a preset electric field strength; According to the first geometric parameter and the second geometric parameter, a cavity portion is machined inside the housing (1), and is engaged with a side of the circuit board where the thin film resistor is present; A first pressure-sensitive element and a second pressure-sensitive element are arranged in the cavity portion, and after the first pressure-sensitive element and the second pressure-sensitive element are arranged, an electrical interface (2) connected to the circuit board and a pagoda nozzle (3) for inputting the measured medium are respectively arranged at the bottom of the housing (1).

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