Piston gas flow detection method and system

Abstract

The present application relates to the technical field of flow test calibration, and discloses a piston type gas flow detection method and system, a calibration device management folder is called, a calibration device management table in the calibration device management folder is selected, if the flow measurement range of a to-be-tested flow meter matches the calibration device range of the selected calibration device management table, the selected calibration device is included in an execution test folder, and through calibration device management information in the calibration device management folder, a plurality of calibration devices can be called to test the to-be-tested flow meter, the probability of measurement error of a single calibration device is reduced, and through range matching, the error caused by calibration devices with different measurement widths can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a piston type gas flow detection method and system, belonging to the technical field of flow test calibration. BACKGROUND

[0002] The active piston type gas flow standard device, referred to as a calibrator, is a gas flow calibrator of volumetric measurement principle, which has the significant characteristics of reference level measurement accuracy, wide measurement flow range, stable measurement performance, high work efficiency, etc. The calibrator is mainly used for critical flow Venturi nozzle, wet type gas flowmeter and thermal type gas mass flowmeter verification and calibration and related flow detection scientific experimental research.

[0003] The traditional calibrator has the following problems affecting the accuracy of flow test results due to its own structural problems:

[0004] The standard flow provided by the calibrator under constant temperature and pressure is the product of the cylinder bore and the piston displacement. Since the traditional calibrator has an uncertainty in its own cylinder volume, there is a problem of accuracy deviation of the flow test results in the process of detecting gas flow.

[0005] When the calibrator is used, whether measuring cumulative flow or instantaneous flow, there is a timing uncertainty in the action time and feedback time of the entire calibrator, which causes the problem of accuracy deviation of the flow test results.

[0006] It is necessary to solve the problem of accuracy deviation of the results in the process of flow test of the traditional calibrator. Therefore, the present application provides a piston type gas flow detection method and system. SUMMARY

[0007] The present application provides a piston type gas flow detection method and system, which can solve the problem of accuracy deviation of the results in the process of flow test of the calibrator.

[0008] The piston type gas flow detection method provided by the present application comprises:

[0009] Receiving physical parameters of each calibration device to form a calibration device management folder.

[0010] Establishing a gas flow standard detection algorithm by using a positive pressure calibration script and a negative pressure calibration script.

[0011] Selecting a calibration device in the calibration device management folder.

[0012] According to the physical parameters of the calibration device, an instruction to start a stable pressure gas source tank or a vacuum device is issued.

[0013] Obtaining the gas flow parameters of the first flowmeter and the gas flow parameters of the second flowmeter.

[0014] The gas flow parameter of the first flowmeter and the gas flow parameter of the second flowmeter are introduced into the gas flow standard detection algorithm.

[0015] The detection gas flow data of the calibration device is obtained.

[0016] One of the calibration devices in the selected calibration device management folder is returned until all the calibration devices are selected.

[0017] Based on the received measurement data of the flowmeter to be tested, the detection gas flow data, the detection result of the flowmeter to be tested is obtained.

[0018] Specifically, the physical parameters of different calibration devices are inconsistent, and the calibration device includes the body of the piston type gas flow standard device, the device rack, the servo motor, the precision ball screw, the Renishaw grating ruler, the meter testing workbench, the atmospheric pressure sensor, the pressure sensor, the differential pressure sensor, the temperature sensor, the humidity transmitter, the connecting pipeline and the air control valve, and the PLC control system.

[0019] The PLC control system can be in communication connection with the servo motor, the Renishaw grating ruler, the atmospheric pressure sensor, the pressure sensor, the differential pressure sensor, the temperature sensor, the humidity transmitter, and the air control valve. The PLC control system as a data node can be in communication connection with the upper computer to realize data intercommunication.

[0020] The more core physical element in the body of the piston type gas flow standard device is the cylindrical piston of the body, and the cylindrical piston of the body slides in the two piston cylinders of the body. The more core physical parameter in the body of the piston type gas flow standard device is the diameter of the cylindrical piston and the stroke of the cylindrical piston. The detection gas flow data provided by the body of the standard device under constant temperature and constant pressure is the quotient of the inner diameter of the cylinder and the displacement of the piston in the displacement time interval.

[0021] The inner diameter of the cylinder is precisely measured before the installation of the cylindrical piston, and the reference standard volume replaced by the calibrator can be calculated in combination with the displacement parameter and the temperature and pressure parameters. Since there is uncertainty in the cylinder volume of the piston type gas flow standard device, the positive pressure calibration script and / or the negative pressure calibration script are used to establish the gas flow standard detection algorithm, so as to reduce the influence of the uncertainty of the volume of the standard device on the detection gas flow data in the process of obtaining the detection gas flow data.

[0022] The physical parameters of the calibration device have three kinds, one is a large cylindrical piston, the outer surface of the large cylindrical piston is plated with hard chromium and finely ground, the effective volume is 200 liters, the diameter is 500 millimeters, and the effective stroke is 1020 millimeters. Another is a medium cylindrical piston, the outer surface of the medium cylindrical piston is plated with hard chromium and finely ground, the effective volume is 20 liters, the diameter is 215 millimeters, and the effective stroke is 555 millimeters. The third is a small cylindrical piston, the outer surface of the small cylindrical piston is plated with hard chromium and finely ground, the effective volume is 800 milliliters, the diameter is 50 millimeters, and the effective stroke is 410 millimeters.

[0023] Therefore, the large cylindrical piston can realize 0.1 cubic meters per hour to 10 cubic meters per hour of airflow flow detection. The medium cylindrical piston can realize 0.01 cubic meters per hour to 1 cubic meter per hour of airflow flow detection. The small cylindrical piston can realize 0.0003 cubic meters per hour to 0.03 cubic meters per hour of airflow flow detection.

[0024] Since the calibration device as a calibrator for detecting airflow flow data has timing uncertainty, positive pressure calibration scripts and negative pressure calibration scripts can be used to form an airflow standard detection algorithm. The airflow standard detection algorithm can be used to verify the airflow flow of the stable airflow passing through the calibration device. The airflow standard detection algorithm can reduce the volume uncertainty and timing uncertainty of the calibration device in the process of verifying the airflow flow of the stable airflow.

[0025] Briefly, the calibration device management folder has multiple calibration devices, and when the flow range of the flow meter to be tested matches the calibration device in the calibration device management folder, the range-matched calibration device can be used as the airflow flow detection device of the flow meter to be tested. This can reduce the influence of volume uncertainty and timing uncertainty of the calibration device on the final detection result.

[0026] It can be understood that according to the physical parameters of the calibration device, the matching degree of the flow range of the flow meter to be tested and the flow range of the calibration device is actually determined. Based on the physical parameters of the calibration device, instructions for starting the pressure stabilizing gas source tank or the vacuumizer are issued, positive pressure calibration scripts and negative pressure calibration scripts can be executed, and then the detection airflow flow data of the calibration device is obtained. Based on the received measurement data of the flow meter to be tested and the detection airflow flow data, it can be determined whether the flow meter to be tested is damaged.

[0027] Further, at least one calibration device management table is established.

[0028] A calibration device management table is selected.

[0029] The piston diameter parameter, the piston stroke parameter, the first cavity stagnation pressure, and the second cavity stagnation pressure of the calibration device are received.

[0030] The piston diameter parameter, the piston stroke parameter, the stagnation pressure of the first cavity and the stagnation pressure of the second cavity of the calibration device are taken as physical parameters of the calibration device.

[0031] Based on the piston diameter parameter and the piston stroke parameter in the physical parameters, a set of geometric feature points of the calibration device is generated.

[0032] The set of geometric feature points is processed by a convex hull algorithm to obtain a set of convex hull boundary points, and the number of edges of a convex polygon corresponding to the set of convex hull boundary points is determined.

[0033] The interior angle of a regular polygon is calculated based on the number of edges of the convex polygon by a regular polygon interior angle calculation algorithm.

[0034] The interior angle of the regular polygon is stored in a calibration device management table together with the physical parameters.

[0035] The selection of one calibration device management table is returned until all calibration device management tables are selected.

[0036] Each calibration device management table is included in a calibration device management folder.

[0037] Specifically, generally, three calibration device management tables can be established to save the piston diameter parameter, the piston stroke parameter, the stagnation pressure of the first cavity and the stagnation pressure of the second cavity of each calibration device.

[0038] The large cylindrical piston is heavy, and is installed in a vertical structure to ensure good stress and motion state. During equipment inspection or sealing maintenance, the front cylinder sleeve can be removed to achieve the purpose. The medium cylindrical piston is light in weight, and is installed in a horizontal structure, so that the equipment installation, inspection and maintenance are relatively easy. The screw rod and the cylindrical piston are installed on the same center shaft, and the screw rod is well stressed. During equipment inspection or sealing maintenance, the slider connected with the left cylinder sleeve can be slid to achieve the purpose. The small cylindrical piston is small in stress, and in order to design the device structure to be exquisite and small, the power mechanism adopts a precise module integrated structure, and the module is installed between the two pistons, so that the structure is compact.

[0039] According to the physical parameters of the calibration device, the range of the gas flow measured by the calibration device can be determined, so as to judge whether the range of the gas flow of the to-be-tested flowmeter matches the range of the gas flow of the calibration device. Through the detection of the gas flow by multiple calibration devices, it can be more objective and accurate to determine whether the to-be-tested flowmeter is damaged.

[0040] Further, a stable pressure starting instruction set and a stable pressure closing instruction set of the stable pressure gas source tank are established.

[0041] Based on the stable pressure starting instruction set, the stable pressure gas source tank is started.

[0042] receiving the value of the stagnation pressure of the first cavity, the value of the stagnation pressure of the second cavity.

[0043] judging whether the value of the stagnation pressure of the first cavity is within a standard range.

[0044] if the value of the stagnation pressure of the first cavity is not within the standard range, returning to receiving the value of the stagnation pressure of the first cavity, the value of the stagnation pressure of the second cavity until the value of the stagnation pressure of the first cavity is within the standard range.

[0045] if the value of the stagnation pressure of the first cavity is within the standard range, judging whether the value of the stagnation pressure of the second cavity is within the standard range.

[0046] if the value of the stagnation pressure of the second cavity is not within the standard range, returning to receiving the value of the stagnation pressure of the first cavity, the value of the stagnation pressure of the second cavity until the value of the stagnation pressure of the second cavity is within the standard range.

[0047] if the value of the stagnation pressure of the second cavity is within the standard range, receiving the piston stable running speed data of the calibration device.

[0048] Specifically, the piston type gas flow detection method can measure the sonic nozzle, high pressure loss detected flowmeter and low pressure loss detected meter. The basic principle of the piston type gas flow detection method is to use the gas with stable pressure and constant temperature to pass through the left and right cavities of the same piston, and the piston runs close to the speed of the nozzle. After uniform speed running, the isolation valve of the left and right cavities is closed, the stagnation pressure in the piston is monitored, the flow rate is adjusted, and finally the stagnation pressure remains unchanged.

[0049] The stagnation pressure of the first cavity remains unchanged, and it can be determined that the value of the stagnation pressure of the first cavity is within the standard range.

[0050] The stagnation pressure of the second cavity remains unchanged, and it can be determined that the value of the stagnation pressure of the second cavity is within the standard range.

[0051] When the value of the stagnation pressure of the second cavity is within the standard range, the received piston stable running speed data of the calibration device is used. Using the product value of the piston stable running speed data and the cross-sectional area of the piston, the initial data of the detected gas flow can be determined.

[0052] Further, based on the gateway of the upper computer itself, the grating ruler incoming data of the calibration device is received.

[0053] The grating ruler incoming data of the calibration device is analyzed.

[0054] The running stroke of the piston and the running time of the piston are obtained.

[0055] The piston's running stroke and the piston's running time are used to obtain the piston's grating ruler calculated speed data.

[0056] It is determined whether the piston stable running speed data of the calibration device matches the grating ruler calculated speed data.

[0057] If the piston stable running speed data of the calibration device does not match the grating ruler calculated speed data, the gateway based on the host computer itself is returned to receive the grating ruler incoming data of the calibration device until the grating ruler calculated speed data is consistent in the system time coordinate.

[0058] If the piston stable running speed data of the calibration device matches the grating ruler calculated speed data, the gas flow data flowing through the calibration device is calculated using the piston stable running speed data or the grating ruler calculated speed data.

[0059] Specifically, the grating ruler of the calibration device is used to directly test the piston stable running speed data of the calibration device. This increases the diversity of the detected gas flow data source. The piston's running stroke and the piston's running time can be obtained using the grating ruler of the calibration device. The piston stable running speed data of the calibration device can be obtained using the piston's running stroke and the piston's running time. The initial data of the detected gas flow can also be determined using the product of the piston stable running speed data and the cross-sectional area of the piston.

[0060] The piston's running stroke and the piston's running time measured by the grating ruler of the calibration device reduce the influence of the timing uncertainty of the calibration device on the inaccuracy of the detected gas flow data. The measurement of the piston's running by the grating ruler of the calibration device is not disturbed by the mechanical movement of the piston itself, so the measurement data of the grating ruler of the calibration device can realize the detection of the gas flow flowing through the calibration device.

[0061] Further, a vacuum start instruction set and a vacuum close instruction set of the vacuumizer are established.

[0062] Based on the vacuum start instruction set, the vacuumizer is started.

[0063] The value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are received.

[0064] It is determined whether the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable.

[0065] If the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are not stable, the receiving of the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity is returned until the motor of the vacuumizer moves at a constant speed.

[0066] If the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable, the flow data of the first flowmeter and the flow data of the second flowmeter are called.

[0067] Specifically, the calibration device is composed of a piston, a cylinder, a screw assembly, a motor, a grating ruler, a temperature and pressure sensor, and a computer software and hardware operating system. The device adopts a piston structure and can be used under negative pressure. The working principle of the calibration device is that after the gas establishes a flow state, the motor drives the screw to rotate, the screw rotation drives the screw cap to move in translation, the screw cap translation drives the piston rigidly connected thereto to move in translation, the gas in the cylinder is extruded by the piston translation and flows to the flowmeter to be tested. When the temperature and pressure of the gas in the cylinder are constant, the gas temperature, pressure, piston displacement, and flowmeter indication signal parameters in the synchronous recording time are recorded, and the related measured parameters can be obtained according to the mathematical model.

[0068] Based on the vacuum start instruction set, the vacuum is started.

[0069] When the motor of the vacuum is in a starting state, the motor movement state of the vacuum is unstable. At this time, the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are unstable. It is worth mentioning that the piston slides left and right in the first cavity, the piston slides left and right in the second cavity, and the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are basically consistent.

[0070] When the motor of the vacuum is started for a period of time, the motor movement state of the vacuum is unstable. At this time, the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable. The flow data of the first flowmeter and the flow data of the second flowmeter can be used to determine the detection gas flow data.

[0071] Further, based on the flow data of the first flowmeter and the flow data of the second flowmeter, it is judged whether the flow data of the first flowmeter and the flow data of the second flowmeter match.

[0072] If the flow data of the first flowmeter and the flow data of the second flowmeter do not match, the flow data of the first flowmeter and the flow data of the second flowmeter are returned until the motor of the vacuum moves at a constant speed.

[0073] If the flow data of the first flowmeter and the flow data of the second flowmeter match, the grating ruler data of the calibration device is received.

[0074] The grating ruler data of the calibration device is analyzed.

[0075] The running stroke of the piston and the running time of the piston are obtained.

[0076] The piston's running stroke and the piston's running time are used to obtain the piston's grating ruler calculation speed data.

[0077] The piston's grating ruler calculation speed data is used to obtain the gas flow data flowing through the calibration device.

[0078] The flow data of the first flowmeter or the flow data of the second flowmeter is selected.

[0079] Based on the selected flow data, it is determined whether the selected flow data matches the gas flow data flowing through the calibration device.

[0080] If the selected flow data matches the gas flow data flowing through the calibration device, it is determined that the gas flow measurement of the calibration device is standard.

[0081] If the selected flow data does not match the gas flow data flowing through the calibration device, the calibration device's grating ruler transmission data is returned until the motor of the vacuum device moves at a constant speed.

[0082] Specifically, when the motor of the vacuum device is in a starting state, the motor of the vacuum device is in an unstable state. The entire gas state inside the calibration device is in an unstable state, so the flow data of the first flowmeter and the flow data of the second flowmeter do not match.

[0083] When the motor of the vacuum device is in a stable state, the flow data of the first flowmeter and the flow data of the second flowmeter match. Based on the stable state of the flow data of the first flowmeter and the second flowmeter, it can be determined that the motor of the vacuum device is in a stable state. This reduces the timing uncertainty of the calibration device. At this time, analyzing the calibration device's grating ruler transmission data can obtain the running data of the piston required by the negative pressure calibration script under the negative pressure method.

[0084] The piston's running data is imported into the negative pressure calibration script to calculate the gas flow data flowing through the calibration device. The first flowmeter or the second flowmeter will measure a specific flow data. If the flow data measured by the first flowmeter or the second flowmeter does not match the gas flow data flowing through the calibration device, it indicates that the motor of the vacuum device is in a starting state, which reduces the timing uncertainty of the calibration device. If the selected flow data matches the gas flow data flowing through the calibration device, it can be determined that the gas flow measurement of the calibration device is standard.

[0085] Further, the flow range of the flowmeter to be tested is received.

[0086] The calibration device management folder is called.

[0087] A calibration device management table in the calibration device management folder is selected.

[0088] determining whether the flow meter range to be tested matches the calibration device range of the selected calibration device management table.

[0089] If the flow meter range to be tested does not match the calibration device range of the selected calibration device management table, returning to one of the calibration device management tables in the selected calibration device management folder until all the calibration device management tables are selected.

[0090] If the flow meter range to be tested matches the calibration device range of the selected calibration device management table, selecting the calibration device into the test execution folder, returning to one of the calibration device management tables in the selected calibration device management folder until all the calibration device management tables are selected.

[0091] Specifically, the calibration device management folder is called, one of the calibration device management tables in the calibration device management folder is selected, and if the flow meter range to be tested matches the calibration device range of the selected calibration device management table, the selected calibration device is selected into the test execution folder. The host computer can call multiple calibration devices to test the flow meter to be tested through the calibration device management information in the calibration device management folder, thereby reducing the probability of measurement error of a single calibration device, and through the matching of the range, the error caused by the calibration devices with different measurement widths can be reduced.

[0092] Further, the test execution folder is called.

[0093] One of the calibration devices in the test execution folder is selected.

[0094] The measurement data of the flow meter to be tested and the detected air flow data of the selected calibration device are called.

[0095] Determining whether the measurement data of the flow meter to be tested matches the detected air flow data.

[0096] If the measurement data of the flow meter to be tested does not match the detected air flow data, it is determined that the flow meter to be tested is damaged.

[0097] If the measurement data of the flow meter to be tested matches the detected air flow data, it is determined that the flow meter to be tested is intact.

[0098] Returning to one of the calibration devices in the selected test execution folder until all the calibration devices are selected.

[0099] Specifically, the host computer can compare the flow data detected by the plurality of calibration devices with the measurement data of the flow meter to be tested, and determine the working condition of the flow meter to be tested multiple times. Each time a calibration device in the test folder is selected to execute, it can be determined whether the flow meter to be tested is damaged or not. When all calibration devices determine that the flow meter to be tested is good, the test result of the flow meter to be tested is obtained. When any calibration device determines that the flow meter to be tested is damaged, it is determined that the flow meter to be tested is damaged.

[0100] The piston gas flow detection system provided by the application comprises:

[0101] The pressure stabilizing gas source tank comprises a tank body and a pressure regulator, and the gas outlet end of the tank body is in communication with the gas inlet end of the pressure regulator.

[0102] The heat exchanger is in communication with the gas outlet end of the pressure regulator.

[0103] The calibration device is in communication with the gas outlet end of the heat exchanger.

[0104] The vacuum device comprises a vacuum tank and a vacuum pump, the vacuum tank is in communication with the vacuum pump, and the gas inlet end of the vacuum tank is in communication with the gas outlet end of the calibration device.

[0105] The first flow meter is arranged between the positive pressure nozzle and the calibration device.

[0106] The second flow meter is arranged away from the gas inlet end of the vacuum tank.

[0107] The host computer is in communication with the pressure regulator, the host computer is in communication with the first flow meter, the host computer is in communication with the second flow meter, and the host computer is used to execute the piston gas flow detection method.

[0108] Further, the calibration device comprises a first bidirectional piston calibrator, a second bidirectional piston calibrator and a third bidirectional piston calibrator.

[0109] The structure of the first bidirectional piston calibrator, the structure of the second bidirectional piston calibrator and the structure of the third bidirectional piston calibrator are the same.

[0110] The first bidirectional piston calibrator is arranged between the heat exchanger and the first flow meter.

[0111] The second bidirectional piston calibrator is arranged between the heat exchanger and the first flow meter.

[0112] The third bidirectional piston calibrator is arranged between the heat exchanger and the first flow meter.

[0113] Specifically, the piston gas flow detection system can detect the calibrated sonic nozzle, high pressure loss gas flow meter and low pressure loss gas flow meter. The piston gas flow detection system can calibrate the sonic nozzle by positive pressure method or negative pressure method, calibrate the passive piston gas flow device, calibrate the gas mass flow meter, volumetric gas flow meter, etc.

[0114] The stable pressure source tank provides a positive pressure source, the positive pressure source passes through the heat exchanger, the positive pressure source provides a gas with stable pressure and constant temperature, the gas passes through the left and right two cavities of the piston and flows through the calibrated sonic nozzle and is discharged into the atmosphere.

[0115] Briefly, when starting, the piston runs at a speed close to the speed of the calibrated sonic nozzle, after uniform speed operation, the isolation valves of the left and right two cavities are closed, the stagnation pressure in the piston is monitored, and the flow rate is adjusted to finally keep the stagnation pressure unchanged, at this time, the piston mass flow is equal to the flow at the calibrated sonic nozzle, and the result can be calculated.

[0116] The inlet end of the calibrated sonic nozzle is connected to the outlet end of the calibration device, the outlet end of the calibration device is connected to the vacuum pump, when running, the piston opens the bypass, the gas enters the piston from the atmosphere and then flows through the calibrated sonic nozzle, after the motor of the vacuum pump runs at a constant speed, the bypass is closed, the stagnation pressure in the piston is monitored, and the flow rate is adjusted to finally keep the stagnation pressure unchanged, at this time, the piston mass flow is equal to the flow at the calibrated sonic nozzle, and the result can be calculated.

[0117] The beneficial effects of the present application are:

[0118] Under constant temperature and pressure, the standard flow provided by the calibrator is the product of the cylinder bore and the piston displacement, the data transmitted by the grating ruler of the calibration device can reduce the uncertainty of the calibration device due to the volume of the cylinder body, so the precision of the flow test result in the process of detecting the gas flow is high.

[0119] When the calibration device is used, the values of the stagnation pressure of the first cavity and the stagnation pressure of the second cavity can determine the measurement stability of the whole device. Whether measuring cumulative flow or instantaneous flow, the timing uncertainty of the action time and feedback time of the calibration device will be reduced, so the precision of the flow test result is high.

[0120] In the calibration device management folder, there are multiple calibration devices, multiple calibration devices with similar ranges can be used to measure the calibrated sonic nozzle in turn. It is worth mentioning that the calibrated sonic nozzle, high pressure loss gas flow meter and low pressure loss gas flow meter can all be the flow devices to be tested. BRIEF DESCRIPTION OF DRAWINGS

[0121] Figure 1A flow chart of a piston type gas flow detection method according to an embodiment of the present application;

[0122] Figure 2 A structure connection diagram of a piston type gas flow detection system according to an embodiment of the present application;

[0123] Reference signs:

[0124] 100-constant pressure gas source tank; 110-tank body; 120-pressure regulator; 200-heat exchanger; 300-calibration device;

[0125] 310-first bidirectional piston calibrator; 320-second bidirectional piston calibrator; 330-third bidirectional piston calibrator;

[0126] 400-vacuum device; 410-vacuum tank; 420-vacuum pump; 500-first flow meter; 600-second flow meter; 700-upper computer. DETAILED DESCRIPTION

[0127] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0128] As shown in Figure 1 , a piston type gas flow detection method provided by the present application comprises:

[0129] S100, receiving physical parameters of each calibration device to form a calibration device management folder.

[0130] Specifically, S110, at least one calibration device management table is established, specifically including: determining the number of tables according to the types of calibration devices to be managed, and establishing tables consistent with the number of calibration device types, for example, three corresponding to large, medium and small pistons. Secondly, the field structure of each table is defined to ensure that the key information of the calibration device can be completely stored, the fields include but are not limited to calibration device unique number, used to distinguish different devices, piston type mark large, medium and small cylindrical pistons, piston diameter parameter unit millimeter, piston stroke parameter unit millimeter, first cavity stagnation pressure unit kilopascal, second cavity stagnation pressure unit kilopascal, geometric feature point set association identifier, convex polygon edge number, regular polygon interior angle unit degree, parameter entry time, operator name. Finally, the table with the above structure is created in the upper computer of the detection system through office software or database tools, and the table is named as a name with recognition, for example, large cylindrical piston calibration device management table, medium cylindrical piston calibration device management table, and stored in the preset calibration device data storage path of the upper computer, ensuring that the table can be edited and queried and the data is not lost.

[0131] S120, a calibration device management table is selected, specifically including: the upper computer interface pops up an interactive window for selecting a calibration device management table, the window lists all established calibration device management table names, for example, large cylindrical piston calibration device management table, medium cylindrical piston calibration device management table, and small cylindrical piston calibration device management table, and displays the current state of each table, such as no data entry, partial data entry, and completed data entry; secondly, the operator clicks the corresponding table name in the window according to the type of calibration device to be processed, for example, if a large cylindrical piston calibration device needs to be processed, the large cylindrical piston calibration device management table is clicked, and if the system supports automatic process, the unprocessed table can be automatically selected in the preset order of large, medium and small. Finally, after selecting the table, the upper computer automatically opens the table and switches the table to data editing mode, and at the same time prompts the current selected table XX calibration device management table at the top of the interface, ensuring that the operator is clear about the table object being processed, and avoiding data confusion caused by selecting the wrong table.

[0132] S130, receiving the piston diameter parameter, the piston stroke parameter, the first cavity stagnation pressure, the second cavity stagnation pressure of the calibration device, specifically comprising: obtaining the parameter source, the piston diameter and stroke are fixed parameters measured precisely when the calibration device is factory, which can be obtained in two ways, one is to read the corresponding value from the factory technical specification of the calibration device, for example, the diameter of the large cylindrical piston is 500mm, the stroke is 1020mm, the second is to use precise measuring tools such as laser diameter gauge and digital micrometer to retest the piston on site, to ensure that the parameters are consistent with the factory values, if the retest value deviates from the factory value by more than ± 0.02mm, contact the equipment manufacturer for confirmation or recalibration. Secondly, parameter input operation, the operator finds the cell corresponding to the piston diameter parameter and the piston stroke parameter in the opened calibration device management table and manually inputs the read or retested value, if the system is connected with the PLC control system of the calibration device, the pre-stored piston diameter and stroke parameters can also be transmitted to the host computer by the PLC to automatically fill the corresponding cells in the table. Finally, parameter verification, after inputting or automatically acquiring the parameters, the host computer automatically verifies whether the value is within a reasonable range, for example, the diameter of the large cylindrical piston is 499.8-500.2mm, and the stroke is 1019.8-1020.2mm, if it exceeds the range, the interface will pop up a prompt that the parameter is abnormal, please reconfirm, until the correct parameter is input.

[0133] Receiving the first cavity and the second cavity stagnation pressure first prepares the pressure collection conditions, connects the first cavity and the second cavity of the calibration device with pressure sensors respectively, the precision grade is not less than 0.1 level, the pressure sensor is connected with the host computer to establish communication connection such as RS485 protocol, to ensure that the pressure data can be transmitted in real time. Secondly, collect pressure data, start the pressure stabilization mode of the calibration device to let the cavity be in a static state without air flow disturbance, after the pressure sensor value is stable and the value fluctuation is not more than ± 0.05kPa within 10 seconds, the operator clicks the acquisition stagnation pressure button of the host computer, the system automatically reads the current value of the first cavity pressure sensor and the second cavity pressure sensor, and displays it in the real-time pressure monitoring module of the interface. Finally, data confirmation and input, the operator checks the displayed two cavity stagnation pressure values, usually the two cavity stagnation pressures should be close to atmospheric pressure such as standard atmospheric pressure 101.325kPa, confirms that there is no error, clicks the confirmation input, the system fills the two pressure values into the first cavity stagnation pressure and the second cavity stagnation pressure cells of the management table respectively.

[0134] S140, taking the piston diameter parameter, the piston stroke parameter, the stalling pressure of the first cavity, and the stalling pressure of the second cavity of the calibration device as the physical parameters of the calibration device, specifically comprising: after the host computer receives the above four parameters, the physical parameter confirmation window is automatically popped up on the interface, and the parameters entered are listed one by one in the window, such as the piston diameter 500 mm, the piston stroke 1020 mm, the stalling pressure of the first cavity 101.3 kPa, and the stalling pressure of the second cavity 101.2 kPa, and the source of each parameter is marked, such as the source of the factory manual and the on-site retest, and the source of the pressure sensor collection. Secondly, the operator carefully checks the parameters in the window to confirm that there is no input error and no abnormal value, for example, if the difference between the stalling pressures of the two cavities exceeds 0.5 kPa, the pressure sensor needs to be checked for normality, if the parameters are correct, click the confirm definition as physical parameters button in the window, if there is an error, click the return to modify button to return to the S130 step to adjust the parameters again. Finally, after clicking the confirmation, the host computer automatically binds the four parameters with the currently selected calibration device, associates them through the unique number of the calibration device, locks and protects the cells of the four parameters in the management table, and only the parameters can be viewed but cannot be modified at will, and the physical parameters have been confirmed in the parameter state field of the table, which is defined as the physical parameters of the calibration device.

[0135] S150, generating a set of geometric feature points of the calibration device based on the piston diameter parameter and the piston stroke parameter in the physical parameters, specifically comprising: determining the generation logic of the set of geometric feature points: the core geometric structure of the calibration device is the piston (cylindrical), and the set of geometric feature points needs to reflect the radial (diameter direction) and axial (stroke direction) profile of the piston, so the point set contains two types of cross-sectional points and axial points.

[0136] Taking the center of the piston cross section as the coordinate origin (0, 0), a two-dimensional rectangular coordinate system is established, and the sampling points on the cross section circle are calculated according to the piston diameter (D): 36 points are usually selected to ensure the profile accuracy, and the angle interval of each sampling point is 10° (360° / 36), the coordinate calculation formula of the i-th sampling point is ((D / 2)×cosθ, (D / 2)×sinθ), wherein θ is the angle of the i-th point (θ=10°×(i-1), i=1 to 36). For example, when the piston diameter is 500 mm, the first point (θ=0°) has coordinates (250, 0), the second point (θ=10°) has coordinates (250×cos10°, 250×sin10°), and so on, to generate the coordinates of 36 cross-sectional points.

[0137] Take one end face of the piston as the axial starting point (z=0) and the other end face as the axial end point (z=stroke S), uniformly select sampling points in the axial direction (usually select 10 points, interval S / 9), each axial point corresponds to a cross section, combine the 36 cross section points of each cross section with the corresponding axial z coordinate to form a three-dimensional coordinate (x, y, z). For example, when the piston stroke is 1020 mm, the axial sampling points z values are 0, 113.33 mm, 226.67 mm, …, 1020 mm, and the 36 cross section points corresponding to each z value form a three-dimensional coordinate (x, y, z), a total of 36x10=360 three-dimensional points are generated.

[0138] The host computer arranges all the generated three-dimensional coordinates (such as 360 points) in the order of "cross section serial number+axial serial number" to form a structured point set data (for example, "point 1: (250, 0, 0), point 2: (250x cos 10°, 250x sin 10°, 0) … point 360: (250x cos 350°, 250x sin 350°, 1020)"), and assigns a unique identifier (such as "large piston-geometric point set-001") to the point set, which is stored in the geometric feature data folder of the host computer, and at the same time, the unique identifier is filled in the geometric feature point set association identifier field of the calibration device management table, realizing the association of the point set and the calibration device.

[0139] S160, processing the geometric feature point set by a convex hull algorithm to obtain a convex hull boundary point set, and determining the number of edges of a convex polygon corresponding to the convex hull boundary point set; calculating the internal angle of a regular polygon based on the number of edges of the convex polygon by a regular polygon internal angle calculation algorithm; storing the internal angle of the regular polygon together with the physical parameters in the calibration device management table, specifically including: analyzing the spatial position relationship of all points according to the geometric feature point set generated in S150, screening out the points that can constitute the outermost boundary of the piston geometric contour, i.e. deleting the points located inside the piston or surrounded by other points, and retaining only the points on the contour surface to form a convex hull boundary point set (for example, after processing the three-dimensional point set, the retained convex hull boundary points are still 360, because the piston is a regular cylinder, all the convex hull points of the axial cross section are boundary points). Secondly, sort the convex hull boundary point set in the order of z coordinate from small to large, and angle from 0° to 360° under the same z coordinate, generate structured convex hull boundary point set data, and display the prompt that the convex hull boundary point set generation is completed, a total of XX points on the interface.

[0140] The host computer groups the convex hull boundary point set according to the same axial z coordinate (i.e. each z coordinate corresponds to a cross-sectional convex hull point), selects an arbitrary cross-sectional convex hull point (such as the cross-sectional convex hull point at z=0) as the analysis object; secondly, the convex hull points of the cross section are sequentially connected in order of angle (from 0° point to 10° point, then to 20° point… Finally, connect back to the 0° point) to form a closed polygon; finally, the number of edges of the polygon is counted, because there are 36 convex hull points in each cross section and they are uniformly distributed, the number of edges of the polygon formed after connection is 36 (i.e. 36 edges), and the host computer records the number of edges of the convex polygon as the number of edges of the convex polygon.

[0141] According to the determined number of edges of the convex polygon (set as n, such as 36), based on the general calculation logic of the internal angle of a regular polygon (the internal angle sum of a regular polygon = (n-2) x 180°, and each internal angle = internal angle sum / n), the internal angle value is calculated, for example, when n=36, the internal angle = (36-2) x 180° / 36 = 34 x 5° = 170°. Secondly, the interface displays the calculation result of the internal angle of the regular polygon, the number of edges n=XX, and the internal angle=XX degrees, for the operator to check.

[0142] After the operator confirms that the number of edges of the convex polygon and the internal angle value of the regular polygon are correct, click the data storage button; the host computer automatically fills the number of edges of the convex polygon (such as 36) into the convex polygon edge number field of the calibration device management table, and fills the internal angle of the regular polygon (such as 170°) into the regular polygon internal angle field. Secondly, the system checks whether the physical parameters (piston diameter, stroke, and two-cavity stagnation pressure) in the table have been stored, and confirms that they are correct, then locks the regular polygon internal angle field for protection, to ensure that it is stored stably with the physical parameters, and can only be viewed in the future, not modified arbitrarily; finally, the data state field of the table is marked as "convex hull processing and internal angle calculation completed", and the data integration of this step is completed.

[0143] S170, return to the selection of one calibration device management table until all calibration device management tables are selected, specifically including: after completing the S120-S160 steps of the current calibration device management table, the host computer automatically checks the established calibration device management table list to determine whether there are tables that have not been selected or have not completed the S160 step (for example, the large cylindrical piston table has been processed, and it is checked whether there are medium and small cylindrical piston tables that have not been processed). Secondly, if there are tables that have not been processed, the host computer interface pops up a prompt to select the next table to be processed, and the table list is displayed again (with the unprocessed tables marked). The operator selects the next table (such as the medium cylindrical piston table) according to the S120 step, and repeats all operations of S120-S160. If the system supports automatic cycling, it can also automatically switch to the next unprocessed table in the preset order (large, medium, and small) without manual selection. Finally, until all established calibration device management tables complete the steps of S120-S160 (i.e., the physical parameters, convex hull edge number, and internal angle of each table have been stored, and the data status is marked as complete), the host computer pops up a prompt that all calibration device management table selection and processing is complete, and the cycle ends.

[0144] S180, include each calibration device management table in the calibration device management folder, specifically including: the host computer creates a root directory named calibration device management folder in the preset storage path, and sets the directory permissions (only system administrators can modify, and operators can only read). Ensure that the directory is not accidentally deleted or tampered with. Secondly, the host computer automatically retrieves all completed calibration device management tables (such as the large cylindrical piston calibration device management table, the medium cylindrical piston calibration device management table, and the small cylindrical piston calibration device management table), and copies these tables into the calibration device management folder (if the original table is stored in other paths, a backup of the original file is retained after copying to avoid data loss). Finally, the host computer creates a directory index table in the calibration device management folder, which records the name of each table, the corresponding calibration device type, the parameter entry completion time, the operator, and the key parameter summary (such as piston diameter, convex hull edge number, and internal angle), which facilitates quick query and positioning when calling the table later. At the same time, a shortcut button to open the calibration device management folder is added to the system interface, which can directly access the folder by clicking, realizing centralized management of all calibration device management tables.

[0145] It can be understood that the large cylindrical piston is heavy in weight, and is installed in a vertical structure to ensure good force stability and movement state. When the equipment is subjected to periodic inspection or sealed maintenance, only the front cylinder sleeve needs to be removed to complete the operation, and the maintenance is convenient. The medium cylindrical piston is light in weight, and is installed in a horizontal structure, which not only simplifies the installation process of the equipment, but also makes the subsequent periodic inspection and maintenance more convenient. In this structure, the lead screw and the cylindrical piston are coaxially installed, which can effectively optimize the force condition of the lead screw. When maintaining, the slider connected with the left cylinder sleeve can realize the opening of the cylinder body, and the operation is efficient. The small cylindrical piston is small in force, and in order to realize the exquisite and compact structure of the device, the power mechanism is designed in a precise module integration, the module is integrated between the two pistons, which greatly reduces the volume of the device, and at the same time ensures the structural stability.

[0146] Combined with the physical parameters (such as piston diameter, stroke) of the calibration device, the range of the measured gas flow can be determined, and then it can be judged whether the range of the to-be-tested flowmeter matches the calibration device. Through the synchronous or step-by-step detection of multiple calibration devices on the gas flow, the limitation of single device detection can be avoided, and whether the to-be-tested flowmeter has damage problem can be more objectively and accurately judged.

[0147] By determining the table fields (such as piston parameters, pressure data, geometric feature identifiers, etc.), the systematic classification management of key information of the calibration device is realized, and parameter storage confusion is avoided; through interface prompts and state labels (such as no data entry, completed entry), the operator can quickly lock the current table object to be processed, reduce the error of selecting the wrong table, and improve the parameter processing efficiency; through the double modes of factory data reading and on-site retesting, the piston parameters and the cavity stagnation pressure after pressure stabilization are acquired, and a numerical verification mechanism is matched to ensure the authenticity and accuracy of the parameters, and to lay a reliable data foundation for subsequent flow calculation and range matching; through the parameter confirmation window and cell lock protection, the key parameters (diameter, stroke, stagnation pressure) are bound and fixed with the calibration device to prevent data modification and ensure the uniqueness and authority of physical parameters; based on the piston diameter and stroke, a three-dimensional geometric point set is generated to accurately restore the radial and axial profiles of the piston, providing data support for subsequent compensation of geometric errors through the convex hull algorithm, and avoiding the flow calculation deviation caused by ambiguous geometric description; through the convex hull algorithm, the piston profile boundary points are screened, the number of convex polygon edges and the internal angle are calculated, the geometric error caused by the piston machining tolerance is corrected, the accuracy of subsequent air flow calculation is further improved, and the internal angle data is stored in coordination with the physical parameters to enrich the feature dimension of the calibration device; through automatic checking of unprocessed tables and cyclic execution of operations, it is ensured that all calibration devices (large, medium and small pistons) complete parameter entry and geometric processing, and avoid missing some devices; through creating a root directory, backing up original files, and generating a directory index table, centralized storage and quick query of all calibration device tables are realized, which facilitates subsequent table calling for range matching and flowmeter detection, and improves the convenience and security of overall data management.

[0148] S200, a gas flow standard detection algorithm is established by using the positive pressure calibration script and the negative pressure calibration script.

[0149] Specifically, S211, a stable pressure start instruction set and a stable pressure close instruction set of the stable pressure gas source tank are established.

[0150] S212, the stable pressure gas source tank is started based on the stable pressure start instruction set.

[0151] S213, the values of the stagnation pressure of the first cavity and the stagnation pressure of the second cavity are received.

[0152] S214, it is judged whether the value of the stagnation pressure of the first cavity is within a standard range.

[0153] S215, if the value of the stagnation pressure of the first cavity is not within the standard range, the values of the stagnation pressure of the first cavity and the stagnation pressure of the second cavity are returned until the value of the stagnation pressure of the first cavity is within the standard range.

[0154] S216, if the value of the stagnation pressure of the first cavity is in the standard range, determining whether the value of the stagnation pressure of the second cavity is in the standard range.

[0155] S217, if the value of the stagnation pressure of the second cavity is not in the standard range, returning to receiving the value of the stagnation pressure of the first cavity, the value of the stagnation pressure of the second cavity until the value of the stagnation pressure of the second cavity is in the standard range.

[0156] S218, if the value of the stagnation pressure of the second cavity is in the standard range, receiving the piston stable running speed data of the calibration device.

[0157] The piston type gas flow detection method can detect the sonic nozzle, high pressure loss detected flowmeter and low pressure loss detected meter. The basic principle of the piston type gas flow detection method is that the gas with stable pressure and constant temperature passes through the left and right cavities of the same piston, the piston runs close to the speed of the nozzle, and after uniform speed running, the isolation valve of the left and right cavities is closed, the stagnation pressure in the piston is monitored, the flow rate is adjusted, and finally the stagnation pressure remains unchanged.

[0158] It can be understood that S221, based on the gateway of the upper computer itself, receives the grating ruler incoming data of the calibration device.

[0159] S222, analyzing the grating ruler incoming data of the calibration device.

[0160] S223, obtaining the running stroke of the piston and the running time of the piston.

[0161] S224, using the running stroke of the piston and the running time of the piston to obtain the grating ruler calculation speed data of the piston.

[0162] S225, determining whether the piston stable running speed data of the calibration device matches the grating ruler calculation speed data.

[0163] S226, if the piston stable running speed data of the calibration device does not match the grating ruler calculation speed data, returning to receiving the grating ruler incoming data of the calibration device based on the gateway of the upper computer itself until the grating ruler calculation speed data is consistent in the system time coordinate.

[0164] S227, if the piston stable running speed data of the calibration device matches the grating ruler calculation speed data, using the piston stable running speed data or the grating ruler calculation speed data to calculate the gas flow data flowing through the calibration device.

[0165] The grating ruler of the calibration device is used for directly testing the stable running speed data of the piston of the calibration device. This increases the diversity of the detected gas flow data sources. By using the grating ruler of the calibration device, the running stroke of the piston and the running time of the piston can be obtained. By using the running stroke of the piston and the running time of the piston, the stable running speed data of the piston of the calibration device can be obtained. By using the product value of the stable running speed data of the piston and the sectional area of the piston, the initial data for detecting the gas flow can also be determined.

[0166] Briefly, S231, the vacuum start instruction set and the vacuum close instruction set of the vacuumizer are established.

[0167] S232, based on the vacuum start instruction set, the vacuumizer is started.

[0168] S233, the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are received.

[0169] S234, it is determined whether the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable.

[0170] S235, if the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are not stable, return to receive the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity until the motor of the vacuumizer moves at a constant speed.

[0171] S236, if the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable, the flow data of the first flowmeter and the flow data of the second flowmeter are called.

[0172] The calibration device is composed of a piston, a cylinder, a screw assembly, a motor, a grating ruler, a temperature and pressure sensor, and a computer software and hardware operating system. The device adopts a piston structure and can be used under negative pressure. The working principle of the calibration device is that after the gas establishes a flow state, the motor drives the screw to rotate, the screw rotation drives the screw cap to move in translation, the screw cap translation movement makes the rigidly connected piston move in translation, the gas in the cylinder is extruded by the piston translation and flows to the flowmeter to be tested. When the temperature and pressure of the gas in the cylinder are constant, the temperature, pressure, piston displacement and flowmeter indication signal parameters in the time are recorded synchronously, and the related measured parameters can be obtained according to the mathematical model.

[0173] Based on the vacuum start instruction set, the vacuumizer is started.

[0174] When the motor of the vacuum device is in the starting state, the motor movement state of the vacuum device is unstable. At this time, the first cavity of the piston left and right sliding, the piston in the second cavity left and right sliding, the first cavity of the stalling pressure value and the second cavity of the stalling pressure value is basically consistent.

[0175] When the motor of the vacuum device is in the starting state, the motor movement state of the vacuum device is unstable. At this time, the first cavity of the piston left and right sliding, the piston in the second cavity left and right sliding, the first cavity of the stalling pressure value and the second cavity of the stalling pressure value is basically consistent.

[0176] Specifically, S241, based on the flow data of the first flowmeter, the flow data of the second flowmeter, whether the flow data of the first flowmeter and the flow data of the second flowmeter match.

[0177] S242, if the flow data of the first flowmeter and the flow data of the second flowmeter do not match, return to call the flow data of the first flowmeter and the flow data of the second flowmeter until the motor of the vacuum device moves at a constant speed.

[0178] S243, if the flow data of the first flowmeter and the flow data of the second flowmeter match, receive the grating ruler data of the calibration device.

[0179] S244, analyze the grating ruler data of the calibration device.

[0180] S245, obtain the running stroke of the piston and the running time of the piston.

[0181] S246, using the running stroke of the piston and the running time of the piston, obtain the grating ruler calculation speed data of the piston.

[0182] S247, based on the grating ruler calculation speed data of the piston, obtain the gas flow data flowing through the calibration device.

[0183] S248, select the flow data of the first flowmeter or the flow data of the second flowmeter.

[0184] S249, based on the selected flow data, determine whether the selected flow data matches the gas flow data flowing through the calibration device.

[0185] S249a, if the selected flow data matches the gas flow data flowing through the calibration device, determine that the gas flow measurement of the calibration device is standard.

[0186] S249b, if the selected flow data does not match the gas flow data through the calibration device, return the grating scale transmission data of the calibration device, until the motor of the vacuum device moves at a constant speed.

[0187] The operation data of the piston is imported into the negative pressure calibration script, and the gas flow data through the calibration device can be calculated. The first flowmeter or the second flowmeter measures a specific flow data. If the flow data measured by the first flowmeter or the second flowmeter does not match the gas flow data through the calibration device, it indicates that the motor of the vacuum device is in a starting state, which reduces the timing uncertainty of the calibration device. If the selected flow data matches the gas flow data through the calibration device, it can be determined that the gas flow measurement of the calibration device is standard.

[0188] S300, select one calibration device in the calibration device management folder.

[0189] S400, according to the physical parameters of the calibration device, issue a command to start the stable pressure source tank or the vacuum device.

[0190] Specifically, S410, receive the flow measurement range to be tested.

[0191] S420, call the calibration device management folder.

[0192] S430, select one calibration device management table in the calibration device management folder.

[0193] S440, determine whether the flow measurement range to be tested matches the calibration device measurement range of the selected calibration device management table.

[0194] S450, if the flow measurement range to be tested does not match the calibration device measurement range of the selected calibration device management table, return to select one calibration device management table in the calibration device management folder, until all calibration device management tables are selected.

[0195] S460, if the flow measurement range to be tested matches the calibration device measurement range of the selected calibration device management table, include the selected calibration device in the execution test folder, and return to select one calibration device management table in the calibration device management folder, until all calibration device management tables are selected.

[0196] The calibration device management folder is called, one calibration device management table in the calibration device management folder is selected, if the flow meter test range matches the calibration device range of the selected calibration device management table, the selected calibration device is included in the execution test folder, and the host computer can call multiple calibration devices to test the flow meter to be tested through the calibration device management information in the calibration device management folder, so as to reduce the probability of measurement error of a single calibration device, and through the range matching, the error caused by the calibration devices with different measurement widths can be reduced.

[0197] S500, obtain the gas flow parameter of the first flowmeter and the gas flow parameter of the second flowmeter.

[0198] S600, import the gas flow parameter of the first flowmeter and the gas flow parameter of the second flowmeter into the gas flow standard detection algorithm.

[0199] S700, obtain the detection gas flow data of the calibration device.

[0200] S800, return to one calibration device in the selected calibration device management folder until all calibration devices are selected.

[0201] S900, based on the received measurement data of the flow meter to be tested and the detection gas flow data, obtain the detection result of the flow meter to be tested.

[0202] Specifically, S910, the execution test folder is called.

[0203] S920, select one calibration device in the execution test folder.

[0204] S930, call the measurement data of the flow meter to be tested and the detection gas flow data of the selected calibration device.

[0205] S940, judge whether the measurement data of the flow meter to be tested matches the detection gas flow data.

[0206] S950, if the measurement data of the flow meter to be tested does not match the detection gas flow data, it is determined that the flow meter to be tested is damaged.

[0207] S960, if the measurement data of the flow meter to be tested matches the detection gas flow data, it is determined that the flow meter to be tested is intact.

[0208] S970, return to one calibration device in the selected execution test folder until all calibration devices are selected.

[0209] The host computer can compare the detected air flow data of the plurality of calibration devices with the measurement data of the flow meter to be tested, and can determine the working condition of the flow meter to be tested multiple times. Each time a calibration device in the test folder is selected to execute, it can be determined whether the flow meter to be tested is damaged or not. When all calibration devices determine that the flow meter to be tested is good, the detection result of the flow meter to be tested is obtained. When any one calibration device determines that the flow meter to be tested is damaged, it is determined that the flow meter to be tested is damaged.

[0210] The standard flow provided by the calibrator under constant temperature and pressure is the product of the cylinder bore and the piston displacement. The use of the grating scale of the calibration device to input data can reduce the uncertainty of the calibration device due to the volume of the cylinder body. Therefore, the accuracy of the flow test result is high during the detection of the gas flow.

[0211] When the calibration device is in use, the stable values of the stagnation pressure of the first cavity and the stagnation pressure of the second cavity can determine the measurement stability of the entire device. Whether measuring cumulative flow or instantaneous flow, the timing uncertainty of the action time and feedback time of the calibration device will be reduced, and therefore the accuracy of the flow test result will be improved.

[0212] As shown in Figure 2 , in one embodiment of the present application, a piston type gas flow detection system includes a pressure stabilizing gas source tank 100, a heat exchanger 200, a calibration device 300, a vacuum device 400, a first flow meter 500, a second flow meter 600, and a host computer 700.

[0213] The pressure stabilizing gas source tank 100 includes a tank body 110 and a pressure regulator 120, and the gas outlet end of the tank body 110 is in communication with the gas inlet end of the pressure regulator 120.

[0214] The gas inlet end of the heat exchanger 200 is in communication with the gas outlet end of the pressure regulator 120.

[0215] The gas outlet end of the heat exchanger 200 is in communication with the gas inlet end of the calibration device 300.

[0216] The vacuum device 400 includes a vacuum tank 410 and a vacuum pump 420, and the vacuum tank 410 is in communication with the vacuum pump 420. The gas inlet end of the vacuum tank 410 is in communication with the gas outlet end of the calibration device 300.

[0217] The first flow meter 500 is arranged at the gas outlet end of the calibration device 300.

[0218] The second flow meter 600 is arranged away from the gas inlet end of the vacuum tank 410.

[0219] The host computer 700 is in communication connection with the pressure regulator 120, the host computer 700 is in communication connection with the calibration device 300, the host computer 700 is in communication connection with the first flowmeter 500, the host computer 700 is in communication connection with the second flowmeter 600, and the host computer 700 is used to execute the piston gas flow detection method.

[0220] Specifically, the calibration device 300 includes a first bidirectional piston calibrator 310, a second bidirectional piston calibrator 320, and a third bidirectional piston calibrator 330.

[0221] The structure of the first bidirectional piston calibrator 310, the structure of the second bidirectional piston calibrator 320, and the structure of the third bidirectional piston calibrator 330 are the same.

[0222] The first bidirectional piston calibrator 310 is arranged between the heat exchanger 200 and the first flowmeter 500.

[0223] The second bidirectional piston calibrator 320 is arranged between the heat exchanger 200 and the first flowmeter 500.

[0224] The third bidirectional piston calibrator 330 is arranged between the heat exchanger 200 and the first flowmeter 500.

[0225] It can be understood that the stable pressure gas source tank 100 provides a positive pressure gas source, the positive pressure gas source passes through the heat exchanger 200, the positive pressure gas source provides a gas with stable pressure and constant temperature, the gas passes through the left and right cavities of the piston, and flows into the atmosphere through the calibrated sonic nozzle.

[0226] Briefly, when starting, the piston runs at a speed close to the speed of the calibrated sonic nozzle, after uniform speed running, the isolation valves of the left and right cavities are closed, the stagnation pressure in the piston is monitored, and the flow rate is adjusted to finally keep the stagnation pressure unchanged, at this time, the piston mass flow is equal to the flow at the calibrated sonic nozzle, and the result can be calculated.

[0227] The inlet end of the calibrated sonic nozzle is connected to the gas outlet end of the calibration device 300, the gas outlet end of the calibration device 300 is connected to the vacuum device 400, when running, the piston opens the bypass, the gas enters the piston from the atmosphere and then flows through the calibrated sonic nozzle, after the motor of the vacuum pump 420 runs at a constant speed, the bypass is closed, the stagnation pressure in the piston is monitored, and the flow rate is adjusted to finally keep the stagnation pressure unchanged, at this time, the piston mass flow is equal to the flow at the calibrated sonic nozzle, and the result can be calculated.

[0228] The calibration device 300 is managed in a folder, and there are multiple calibration devices 300, which can be used to sequentially measure the calibration sonic nozzle by using multiple calibration devices 300 with similar ranges. It is worth mentioning that the calibration sonic nozzle, the high-pressure loss gas flowmeter, and the low-pressure loss gas flowmeter can all be flow devices to be tested.

[0229] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application.

[0230] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method of detecting the flow of a gas by means of a piston, characterized in that, The method comprises the following steps: receiving physical parameters of each calibration device to form a calibration device management folder; the piston diameter parameter, the piston stroke parameter, the dead leg pressure of the first cavity and the dead leg pressure of the second cavity are taken as the physical parameters of the calibration device; establishing a gas flow standard detection algorithm by using a positive pressure calibration script and a negative pressure calibration script; selecting one calibration device in the calibration device management folder; issuing a command to start a constant pressure gas source tank or a vacuum device according to the physical parameters of the calibration device; obtaining the gas flow parameter of the first flowmeter and the gas flow parameter of the second flowmeter; introducing the gas flow parameter of the first flowmeter and the gas flow parameter of the second flowmeter into the gas flow standard detection algorithm; obtaining the detection gas flow data of the calibration device; returning to the step of selecting one calibration device in the calibration device management folder until all the calibration devices are selected; obtaining the detection result of the flowmeter to be tested based on the received measurement data of the flowmeter to be tested and the detection gas flow data.

2. The piston gas flow detection method according to claim 1, characterized by, The step of receiving the physical parameters of each calibration device to form the calibration device management folder comprises the following steps: establishing at least one calibration device management table; selecting one calibration device management table; receiving the piston diameter parameter, the piston stroke parameter, the dead leg pressure of the first cavity and the dead leg pressure of the second cavity; generating a set of geometric feature points of the calibration device based on the piston diameter parameter and the piston stroke parameter in the physical parameters; processing the set of geometric feature points by a convex hull algorithm to obtain a set of convex hull boundary points and determine the number of edges of a convex polygon corresponding to the set of convex hull boundary points; calculating the internal angle of the regular polygon based on the number of edges of the convex polygon by a regular polygon internal angle calculation algorithm; storing the internal angle of the regular polygon together with the physical parameters in the calibration device management table; returning to the step of selecting one calibration device management table until all the calibration device management tables are selected; including each calibration device management table in the calibration device management folder.

3. The piston gas flow detection method according to claim 2, wherein In the step of establishing the gas flow standard detection algorithm by using the positive pressure calibration script and the negative pressure calibration script, the step of establishing the positive pressure calibration script comprises the following steps: establishing a set of constant pressure starting instructions and a set of constant pressure closing instructions of the constant pressure gas source tank; starting the constant pressure gas source tank based on the set of constant pressure starting instructions; receiving the value of the dead leg pressure of the first cavity and the value of the dead leg pressure of the second cavity; judging whether the value of the dead leg pressure of the first cavity is within a standard range; if the value of the dead leg pressure of the first cavity is not within the standard range, returning to the step of receiving the value of the dead leg pressure of the first cavity and the value of the dead leg pressure of the second cavity until the value of the dead leg pressure of the first cavity is within the standard range; if the value of the dead leg pressure of the first cavity is within the standard range, judging whether the value of the dead leg pressure of the second cavity is within the standard range; if the value of the dead leg pressure of the second cavity is not within the standard range, returning to the step of receiving the value of the dead leg pressure of the first cavity and the value of the dead leg pressure of the second cavity until the value of the dead leg pressure of the second cavity is within the standard range; If the value of the stagnation pressure of the second cavity is within the standard range, the piston stable running speed data of the calibration device is received.

4. The piston gas flow detection method according to claim 3, characterized by, The positive pressure calibration script is established, and the establishment further includes: Receiving the grating scale incoming data of the calibration device based on the gateway of the upper computer itself; Analyzing the grating scale incoming data of the calibration device; Obtaining the running stroke of the piston and the running time of the piston; Obtaining the grating scale calculation speed data of the piston by using the running stroke of the piston and the running time of the piston; Judging whether the piston stable running speed data of the calibration device matches the grating scale calculation speed data; If the piston stable running speed data of the calibration device does not match the grating scale calculation speed data, returning to receive the grating scale incoming data of the calibration device based on the gateway of the upper computer itself until the grating scale calculation speed data is consistent in the system time coordinate; If the piston stable running speed data of the calibration device matches the grating scale calculation speed data, calculating the gas flow data flowing through the calibration device by using the piston stable running speed data or the grating scale calculation speed data.

5. The piston gas flow detection method according to claim 4, wherein In the establishment of the gas flow standard detection algorithm by using the positive pressure calibration script and the negative pressure calibration script, the negative pressure calibration script is established, and the establishment further includes: Establishing a vacuum start instruction set and a vacuum close instruction set of the vacuum device; Starting the vacuum device based on the vacuum start instruction set; Receiving the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity; Determining whether the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable; If the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are not stable, returning to receive the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity until the motor of the vacuum device moves at a constant speed; If the value of the stagnation pressure of the first cavity and the value of the stagnation pressure of the second cavity are stable, calling the flow data of the first flowmeter and the flow data of the second flowmeter.

6. The piston gas flow detection method of claim 5, wherein, The establishment of the negative pressure calibration script further includes: Based on the flow data of the first flowmeter and the flow data of the second flowmeter, judging whether the flow data of the first flowmeter and the flow data of the second flowmeter match; If the flow data of the first flowmeter and the flow data of the second flowmeter do not match, returning to call the flow data of the first flowmeter and the flow data of the second flowmeter until the motor of the vacuum device moves at a constant speed; If the flow data of the first flowmeter and the flow data of the second flowmeter match, receiving the grating scale incoming data of the calibration device; Analyzing the grating scale incoming data of the calibration device; Obtaining the running stroke of the piston and the running time of the piston; Obtaining the grating scale calculation speed data of the piston by using the running stroke of the piston and the running time of the piston; Based on the grating scale calculation speed data of the piston, obtaining the gas flow data flowing through the calibration device; Selecting the flow data of the first flowmeter or the flow data of the second flowmeter; Based on the selected flow data, judging whether the selected flow data matches the gas flow data flowing through the calibration device; If the selected flow data matches the gas flow data flowing through the calibration device, determining that the gas flow measurement of the calibration device is standard. If the selected flow data does not match the gas flow data flowing through the calibration device, the grating scale transmission data of the receiving calibration device is returned until the motor of the vacuum device moves at a constant speed.

7. The piston gas flow detection method of claim 6, wherein, The instructions for starting the constant pressure gas source tank or the vacuum device are issued according to the physical parameters of the calibration device, and the instructions include: receiving the flow measurement range of the flow meter to be tested; calling the calibration device management folder; selecting one calibration device management table in the calibration device management folder; determining whether the flow measurement range of the flow meter to be tested matches the calibration device measurement range of the selected calibration device management table; if the flow measurement range of the flow meter to be tested does not match the calibration device measurement range of the selected calibration device management table, returning to select one calibration device management table in the calibration device management folder until all calibration device management tables are selected; if the flow measurement range of the flow meter to be tested matches the calibration device measurement range of the selected calibration device management table, the selected calibration device is included in the execution test folder, and returning to select one calibration device management table in the calibration device management folder until all calibration device management tables are selected.

8. The piston gas flow detection method of claim 7, wherein, The detection results of the flow meter to be tested are obtained based on the received measurement data of the flow meter to be tested and the detection gas flow data, and the detection results include: calling the execution test folder; selecting one calibration device in the execution test folder; calling the measurement data of the flow meter to be tested and the detection gas flow data of the selected calibration device; determining whether the measurement data of the flow meter to be tested matches the detection gas flow data; if the measurement data of the flow meter to be tested does not match the detection gas flow data, it is determined that the flow meter to be tested is damaged; if the measurement data of the flow meter to be tested matches the detection gas flow data, it is determined that the flow meter to be tested is intact; returning to select one calibration device in the execution test folder until all calibration devices are selected.

9. A piston gas flow detection system characterized by, It includes: a constant pressure gas source tank including a tank body and a pressure regulator, the gas outlet end of the tank body being in communication with the gas inlet end of the pressure regulator; a heat exchanger, the gas inlet end of the heat exchanger being in communication with the gas outlet end of the pressure regulator; a calibration device, the gas outlet end of the heat exchanger being in communication with the gas inlet end of the calibration device; a vacuum device including a vacuum tank and a vacuum pump, the vacuum tank being in communication with the vacuum pump, the gas inlet end of the vacuum tank being in communication with the gas outlet end of the calibration device; a first flow meter arranged at the gas outlet end of the calibration device; a second flow meter arranged away from the gas inlet end of the vacuum tank; a host computer in communication with the pressure regulator, the host computer in communication with the calibration device, the host computer in communication with the first flow meter, the host computer in communication with the second flow meter, and the host computer for executing the piston gas flow detection method according to any one of claims 1 to 8.

10. The piston gas flow detection system of claim 9, wherein, The calibration device includes a first bidirectional piston calibrator, a second bidirectional piston calibrator, and a third bidirectional piston calibrator; the structure of the first bidirectional piston calibrator, the structure of the second bidirectional piston calibrator, and the structure of the third bidirectional piston calibrator are the same; The first bidirectional piston prover is disposed between the heat exchanger and the first flow meter; The second bidirectional piston prover is disposed between the heat exchanger and the first flow meter; The third bidirectional piston prover is disposed between the heat exchanger and the first flow meter.

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