Full-automatic capacitance film vacuum gauge calibration device

Abstract

The invention discloses a full-automatic capacitance film vacuum gauge calibration device, which comprises a cabinet body, and an inflation unit, a calibration unit, a measurement unit, an air exhaust unit and a control unit which are arranged on the cabinet body, the inflation unit is connected with the measuring unit, the calibration unit and the control unit. The control unit is respectively connected with the calibration unit, the measurement unit and the air exhaust unit; and the air exhaust unit is connected with the calibration unit. The invention solves the technical problem of how to carry out calibration test on a plurality of capacitive thin film vacuum gauges with different measuring ranges and realize real-time pressure, temperature and linearity performance parameter measurement on the capacitive thin film vacuum gauges.

Description

Technical Field

[0001] The invention relates to the technical field of thin film vacuum gauge calibration, and in particular to a full-automatic capacitance thin film vacuum gauge calibration device. Background Art

[0002] Vacuum science and technology is an important part of modern science and technology, including four aspects: vacuum acquisition, vacuum leak detection, vacuum application and vacuum measurement. The work of vacuum measurement is very dependent on various types of pressure sensors, which are also one of the most widely used sensors. During the use of sensors, they need to be calibrated and calibrated to achieve higher measurement accuracy. The calibration process of the sensor is to use higher-level testing equipment certified by the state to calibrate the static indicators of the sensor and calibrate the dynamic indicators.

[0003] In recent years, many researchers have done little research on the accuracy verification and test result correction of capacitance film vacuum gauges. The test standards for capacitance film vacuum gauges have not yet been unified, which leads to uncertainty in the output electrical signal value of capacitance film vacuum gauges. For example, Liu Beibei et al. of Shanghai Institute of Metrology and Testing Technology used the static expansion method to establish a set of measurement range of 10 based on the Boyle-Maliott law. -1 -10 4 Pa, the capacitance film vacuum gauge calibration device with an expanded uncertainty of 0.22% to 0.06%, tested the volume ratio of the device and the uncertainty of the capacitance film vacuum gauge, and provided guidance for the traceability of the absolute pressure capacitance film vacuum gauge measurement value; at the same time, with the interference of various factors on the test results during the detection process, some calibration standards can no longer meet the test requirements of low-range and high-precision capacitance film vacuum gauges. At present, the production of domestic capacitance film vacuum gauges mainly relies on manual manufacturing and assembly. High-precision film vacuum gauges are often assembled, with low yield, extremely low production efficiency, and low degree of intelligence and informatization. Therefore, it is necessary to develop intelligent manufacturing and precision testing, establish standard multi-range measurement and calibration equipment, and achieve the goal of mass production and consistency. Therefore, based on the above technical problems, it is urgent to propose a fully automatic capacitance film vacuum gauge calibration device to solve the technical problem of how to calibrate and test multiple capacitance film vacuum gauges of different ranges and realize the measurement of real-time pressure, temperature and linearity performance parameters of capacitance film vacuum gauges. Summary of the invention

[0004] The main purpose of the present invention is to propose a fully automatic capacitance film vacuum gauge calibration device, which aims to solve the technical problem of how to perform calibration tests on multiple capacitance film vacuum gauges with different ranges and realize real-time pressure, temperature and linearity performance parameter measurement of the capacitance film vacuum gauge.

[0005] To achieve the above object, the present invention provides a fully automatic capacitance film vacuum gauge calibration device, wherein the fully automatic capacitance film vacuum gauge calibration device comprises:

[0006] A cabinet, and an inflation unit, a calibration unit, a measuring unit, an exhaust unit and a control unit placed on the cabinet; the inflation unit is respectively connected to the measuring unit, the calibration unit and the control unit; the control unit is respectively connected to the calibration unit, the measuring unit and the exhaust unit; the exhaust unit is connected to the calibration unit.

[0007] In one preferred embodiment, the inflation unit comprises a pressure stabilizing chamber, a first stop valve, a first inflation pipeline and a second inflation pipeline;

[0008] The pressure stabilizing chamber is connected to the measuring unit and the first stop valve respectively, and the other end of the first stop valve is connected to the first inflation pipeline and the second inflation pipeline respectively.

[0009] One of the preferred schemes, the first inflation pipeline includes a pressure reducing valve and a steel cylinder; one end of the pressure reducing valve is connected to the stop valve, and the other end of the pressure reducing valve is connected to the steel cylinder; the steel cylinder is equipped with a detection gas of a capacitance diaphragm vacuum gauge; the second inflation pipeline includes a second stop valve; one end of the second stop valve is connected to the first stop valve, and the other end of the second stop valve is provided with an inflation interface, and the inflation interface is used to connect to an external standard detection steel cylinder.

[0010] In one of the preferred solutions, a high-pressure inflation pipeline is used between the first inflation pipeline, the second inflation pipeline and the pressure stabilization chamber.

[0011] In one of the preferred embodiments, the inflation unit further includes a first flow meter and a second flow meter; one end of the first flow meter and the second flow meter are connected to the pressure stabilizing chamber, and the other end of the first flow meter and the second flow meter are connected to the calibration unit.

[0012] In one of the preferred embodiments, the measuring unit includes a vacuum gauge A, a vacuum gauge B and a temperature sensor;

[0013] The vacuum gauge A is connected to the calibration unit, the vacuum gauge B is connected to the inflation unit, and the temperature sensor is installed on the cabinet.

[0014] According to one of the preferred embodiments, the calibration unit comprises a calibration chamber and at least one standard vacuum gauge; the standard vacuum gauge is connected to the calibration chamber, and the calibration chamber is respectively connected to the inflation unit and the exhaust unit.

[0015] In one of the preferred solutions, the calibration unit further comprises a calibration interface, an air extraction valve and a flow limiting orifice;

[0016] The calibration interface adopts KF16 interface design;

[0017] The air extraction valve comprises a pneumatic gate valve and an electromagnetic pressure differential valve; one end of the pneumatic gate valve and the electromagnetic pressure differential valve is connected to the calibration chamber, and the other end of the pneumatic gate valve and the electromagnetic pressure differential valve is connected to the air extraction unit;

[0018] The flow-limiting orifice is disposed between the pneumatic gate valve and the air extraction unit.

[0019] In one of the preferred solutions, the air extraction unit includes a first pump, a second pump, an electromagnetic isolation valve and a pneumatic air release valve;

[0020] The first pump is connected to the pneumatic gate valve, the other end of the first pump is connected to the electromagnetic isolation valve, the other end of the electromagnetic isolation valve is connected to the second pump, and the other end of the second pump is connected to the electromagnetic pressure differential valve; the pneumatic air release valve is connected to the calibration chamber.

[0021] One of the preferred schemes, the control unit includes an industrial computer, a protocol converter, a PID controller, a digital-to-analog converter, a pressure transmitter and a vacuum gauge controller; the industrial computer is connected to the PID controller and the digital-to-analog converter respectively through the protocol converter, the digital-to-analog converter is connected to the vacuum gauge controller, the inflation unit and the pressure transmitter respectively, and the vacuum gauge controller and the PID controller are connected to the calibration unit.

[0022] In the above technical solution of the present invention, the fully automatic capacitance film vacuum gauge calibration device includes: a cabinet, and an air charging unit, a calibration unit, a measuring unit, an air extraction unit and a control unit placed on the cabinet; the air charging unit is respectively connected to the measuring unit, the calibration unit and the control unit; the control unit is respectively connected to the calibration unit, the measuring unit and the air extraction unit; the air extraction unit is connected to the calibration unit. The present invention solves the technical problem of how to perform calibration tests on multiple capacitance film vacuum gauges of different ranges and realize the measurement of real-time pressure, temperature and linearity performance parameters of capacitance film vacuum gauges.

[0023] In the present invention, the gas flow rates of the inlet and outlet are automatically controlled, that is, the gas flow rates of the inlet and outlet are controlled by the gas charging unit and the gas extraction unit, so as to control the inlet and outlet pressures, so that they can quickly reach a dynamic equilibrium point, avoiding pressure deviations caused by human factors and slow adjustment; and the minimum pressure of the calibration chamber of the calibration unit can reach 1×10 -3 Pa, can detect capacitance film vacuum gauges with a full scale as low as 1Torr, and has a wide detection range.

[0024] In the present invention, the fully automatic capacitance diaphragm vacuum gauge calibration device uses pressure, temperature, linearity and dynamic stability as the main measurement and adjustment parameters, which can meet the functional requirements of calibrating multiple capacitance diaphragm vacuum gauges at the same time, and can quickly and accurately measure the real-time pressure, temperature, linearity and other performance parameters of the capacitance diaphragm vacuum gauge. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0026] Figure 1 This is a schematic structural diagram of a fully automatic capacitance film vacuum gauge calibration device according to an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of a control unit according to an embodiment of the present invention.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0032] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] See also Figure 1-Figure 2According to one aspect of the present invention, the present invention provides a fully automatic capacitance film vacuum gauge calibration device, wherein the fully automatic capacitance film vacuum gauge calibration device comprises:

[0034] A cabinet, and an inflation unit, a calibration unit, a measuring unit, an exhaust unit and a control unit placed on the cabinet; the inflation unit is respectively connected to the measuring unit, the calibration unit and the control unit; the control unit is respectively connected to the calibration unit, the measuring unit and the exhaust unit; the exhaust unit is connected to the calibration unit.

[0035] Specifically, in this embodiment, a plurality of steering wheels are provided at the bottom of the cabinet. By providing the steering wheels at the bottom of the cabinet, the full-automatic capacitance film vacuum gauge calibration device can be moved and steered in any direction.

[0036] Specifically, in this embodiment, the inflation unit includes a pressure stabilizing chamber, a first stop valve and a first inflation pipeline and a second inflation pipeline; the pressure stabilizing chamber is respectively connected to the measuring unit and the first stop valve, and the other end of the first stop valve is respectively connected to the first inflation pipeline and the second inflation pipeline; the first stop valve is a 1 / 4 corrugated tube stop valve, and the pressure stabilizing chamber adopts a cylindrical structure design with a volume of not less than 1.5L and a working pressure of 10Pa-0.2MPa. The present invention does not make specific limitations and can be set according to needs.

[0037] Specifically, in the present embodiment, the first inflation pipeline comprises a pressure reducing valve and a cylinder; one end of the pressure reducing valve is connected to the stop valve, and the other end of the pressure reducing valve is connected to the cylinder; the cylinder is equipped with a detection gas of a capacitance diaphragm vacuum gauge; the detection gas may be nitrogen, and the cylinder is a 4L, 10MPa standard cylinder; the outlet pressure of the pressure reducing valve is below 0.6MPa, and the accuracy is 2.5%; the second inflation pipeline comprises a second stop valve; one end of the second stop valve is connected to the first stop valve, and the other end of the second stop valve is provided with an inflation interface, and the inflation interface is used to connect to an external standard detection cylinder; the external standard detection cylinder is a 40L, 15MPa standard detection cylinder, and the second stop valve is a 1 / 4 corrugated tube stop valve, which is not specifically limited in the present invention and can be set according to needs.

[0038] Specifically, in this embodiment, high-pressure inflation pipelines are used between the first inflation pipeline and the second inflation pipeline and the pressure stabilizing chamber, and vacuum pipelines are used in other parts.

[0039] Specifically, in this embodiment, the inflation unit also includes a first flow meter and a second flow meter; one end of the first flow meter and the second flow meter is connected to the pressure stabilizing chamber, and the other end of the first flow meter and the second flow meter is connected to the calibration unit; the first flow meter and the second flow meter have different specifications, and the flow rate is measured by the first flow meter and the second flow meter while measuring and adjusting the pressure of the pressure stabilizing chamber and the calibration chamber to achieve flow control.

[0040] Specifically, in this embodiment, the measuring unit includes a vacuum gauge A, a vacuum gauge B and a temperature sensor; the vacuum gauge A is connected to the calibration unit, the vacuum gauge B is connected to the inflation unit, and the temperature sensor is installed on the cabinet; the vacuum gauge A is used to measure the pressure of the calibration chamber, and the vacuum gauge A adopts a capacitance film vacuum gauge. The vacuum gauge A has three ranges, namely 0.1, 10, and 1000 Torr, and the measuring range is 1×10 -3 -1×10 5 Pa; the vacuum gauge B is used to measure the pressure in the stabilizing chamber. The vacuum gauge B adopts a Pirani vacuum gauge. The measurement range of the vacuum gauge B is 1×10 -2 -1×10 5 Pa; the temperature sensor adopts a platinum resistance temperature sensor, which is not specifically limited in the present invention. The vacuum gauge A, vacuum gauge B and temperature sensor can be set as needed.

[0041] Specifically, in this embodiment, the calibration unit includes a calibration chamber and at least one standard vacuum gauge; the standard vacuum gauge is connected to the calibration chamber, and the calibration chamber is respectively connected to the inflation unit and the exhaust unit; the standard vacuum gauge includes an MKS capacitance diaphragm vacuum gauge, the model of the capacitance diaphragm vacuum gauge is 690A, and the range of the standard vacuum gauge is selected according to the range of the diaphragm vacuum gauge being measured during operation.

[0042] Specifically, in this embodiment, the calibration chamber is the core part of the calibration unit. The gas enters the calibration chamber from the cylinder through the pipeline, and then is evacuated by a pump group, that is, a vacuum unit, so that a dynamic balance effect is achieved in the calibration chamber, allowing the capacitance diaphragm vacuum gauge to obtain the required pressure value.

[0043] Specifically, in this embodiment, the calibration unit also includes a calibration interface, an air extraction valve and a flow limiting hole; the calibration interface adopts the KF16 interface design; the air extraction valve includes a pneumatic plug-in valve and an electromagnetic pressure differential valve; one end of the pneumatic plug-in valve and the electromagnetic pressure differential valve is connected to the calibration chamber, and the other end of the pneumatic plug-in valve and the electromagnetic pressure differential valve is connected to the air extraction unit; the flow limiting hole is placed between the pneumatic plug-in valve and the turbomolecular pump, and the flow limiting hole is designed by opening a hole on an oxygen-free copper sealing ring.

[0044] Specifically, in this embodiment, during the test process of the entire calibration device, it is necessary to quickly adjust the inlet and outlet gas pressures in the calibration chamber so that the calibration chamber quickly reaches a dynamic pressure equilibrium state, shorten the preparation time before the capacitance film vacuum gauge calibration work, and thus perform subsequent work more efficiently. For this purpose, a vacuum unit is set for the device to meet the pressure requirements of the calibration device; the vacuum unit includes a first pump, a second pump, an electromagnetic isolation valve and a pneumatic bleed valve; the first pump is connected to the pneumatic plug valve, the other end of the first pump is connected to the electromagnetic isolation valve, the other end of the electromagnetic isolation valve is connected to the second pump, and the other end of the second pump is connected to the electromagnetic pressure differential valve; the pneumatic bleed valve is connected to the calibration chamber; the first pump uses a molecular pump as a main pump, and the second pump uses a vortex pump as a rough pump. Through the cooperation of the molecular pump and the vortex pump, the advantages of the vortex pump being simple in structure, light in weight, and insensitive to system pressure fluctuations are utilized to provide a good fore-stage pressure for the device; at the same time, the molecular pump, as a high vacuum pump, has the advantages of being easy to use and having a strong gas delivery capacity, and can provide a good calibration pressure environment for the capacitance film vacuum gauge and provide the required vacuum environment for the device.

[0045] Specifically, in this embodiment, in order to avoid or reduce the influence of human factors on the detection results and improve the efficiency of the calibration device in measuring the capacitance film vacuum gauge, the control unit is set, and the control unit is coordinated with the inflation unit, the exhaust unit, and the calibration unit to have the functions of vacuum degree regulation and flow regulation, and realize the requirements for functional control of pressure, temperature, flow and speed; the control unit includes an industrial computer, a protocol converter, a PID controller, a digital-to-analog converter, a pressure transmitter and a vacuum gauge controller; the industrial computer is connected to the PID controller and the digital-to-analog converter respectively through the protocol converter, the digital-to-analog converter is connected to the vacuum gauge controller, the inflation unit and the pressure transmitter respectively, and the vacuum gauge controller and the PID controller are connected to the calibration unit; in the present invention, the protocol converter is an RS232 / RS485 protocol converter, the control unit also includes a PLC and a switch, the The PLC is connected to the switch and the industrial computer respectively; when the calibration device starts to work, the cylinder in the charging unit starts to supply gas and throttles through the first stop valve. At this time, a pressure difference will be generated in the pressure stabilizing chamber, and the pressure transmitter converts the pressure value into an electrical signal, which is output to the industrial computer through the digital-to-analog converter and the protocol converter. The industrial computer controls the first flow meter and the second flow meter according to the received model to allow the gas in the cylinder to enter the pressure stabilizing chamber. During the test flow, the amount of incoming flow can be controlled by controlling the opening of the 1 / 4 stop valve A between the pressure stabilizing chamber and the calibration chamber. The vacuum gauge A installed on the calibration chamber converts the real-time pressure value into an electrical signal and transmits the value to the digital-to-analog converter. Then the digital-to-analog converter transmits the electrical signal to the industrial computer through the protocol converter in a serial communication manner. The industrial computer receives the signal and converts it into a vacuum value, compares the vacuum value with the vacuum threshold set by the system, and thus controls the opening of the air extraction unit and the valve to reach the specified pressure value.

[0046] Specifically, in this embodiment, the control of the opening of the vacuum unit and the valve to reach the specified pressure value is as follows: the electromagnetic pressure difference valve and the second pump are opened to roughly pump the calibration chamber, and the electromagnetic pressure difference valve is closed when it reaches 20Pa; the first pump and the pneumatic gate valve are opened to pump the calibration chamber to the background pressure, and this process is the vacuum pumping of the calibration chamber; at the beginning of the test, the first pump and the pneumatic gate valve are first closed, and the 1 / 4 stop valve A is opened, and the calibration chamber reaches the set pressure by controlling the first flow meter and the second flow meter; at the same time, the calibration chamber is maintained within the error range of the specified pressure by opening and closing the 1 / 4 stop valve A and the pumping speed of the second pump, as well as the gas release rate of the leak. When the set pressure is to be reduced, A second pump is used to evacuate air. When the second pump evacuates the pressure in the calibration chamber to the working pressure range of the first pump, the second pump stops working. If the pressure is less than the set value, the first flow meter and the second flow meter are controlled to intake air. If it is still greater than the set value, the first pump works. The gas flow rates at the inlet and outlet are automatically controlled, so as to control the inlet and outlet pressures and quickly reach a dynamic equilibrium point, thereby avoiding pressure deviations and slow adjustments caused by human factors. Moreover, by changing the internal structure of the calibration chamber, the gas is evenly distributed everywhere, thereby making the internal pressure evenly distributed, thereby avoiding inaccurate pressure indication of the capacitance diaphragm vacuum gauge due to pressure errors.

[0047] Specifically, in this embodiment, the linearity of the capacitive diaphragm vacuum gauge is achieved by setting pressure points at intervals of 10% within the measuring range through a calibration device, obtaining a voltage output corresponding to the pressure at each point, and thereby obtaining a calibration curve of the diaphragm vacuum gauge. The maximum deviation between the curve and the fitting straight line and the percentage of the full-scale output is the linearity.

[0048] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A fully automatic capacitance film vacuum gauge calibration device, characterized in that: include: A cabinet, and an inflation unit, a calibration unit, a measuring unit, an exhaust unit and a control unit placed on the cabinet; the inflation unit is respectively connected to the measuring unit, the calibration unit and the control unit; the control unit is respectively connected to the calibration unit, the measuring unit and the exhaust unit; the exhaust unit is connected to the calibration unit.

2. A fully automatic capacitance film vacuum gauge calibration device according to claim 1, characterized in that: The inflation unit comprises a pressure stabilizing chamber, a first stop valve and a first inflation pipeline and a second inflation pipeline; The pressure stabilizing chamber is connected to the measuring unit and the first stop valve respectively, and the other end of the first stop valve is connected to the first inflation pipeline and the second inflation pipeline respectively.

3. A fully automatic capacitance film vacuum gauge calibration device according to claim 2, characterized in that: The first inflation pipeline includes a pressure reducing valve and a steel cylinder; one end of the pressure reducing valve is connected to the stop valve, and the other end of the pressure reducing valve is connected to the steel cylinder; the steel cylinder is equipped with a detection gas of a capacitance diaphragm vacuum gauge; the second inflation pipeline includes a second stop valve; one end of the second stop valve is connected to the first stop valve, and the other end of the second stop valve is provided with an inflation interface, and the inflation interface is used to connect to an external standard detection steel cylinder.

4. The fully automatic capacitance film vacuum gauge calibration device according to claim 2, characterized in that: A high-pressure inflation pipeline is used between the first inflation pipeline, the second inflation pipeline and the pressure stabilization chamber.

5. The fully automatic capacitance film vacuum gauge calibration device according to claim 2, characterized in that: The inflation unit further includes a first flow meter and a second flow meter; one end of the first flow meter and the second flow meter is connected to the pressure stabilizing chamber, and the other end of the first flow meter and the second flow meter is connected to the calibration unit.

6. A fully automatic capacitance film vacuum gauge calibration device according to any one of claims 1 to 5, characterized in that: The measuring unit includes a vacuum gauge A, a vacuum gauge B and a temperature sensor; The vacuum gauge A is connected to the calibration unit, the vacuum gauge B is connected to the inflation unit, and the temperature sensor is installed on the cabinet.

7. A fully automatic capacitance film vacuum gauge calibration device according to any one of claims 1 to 5, characterized in that: The calibration unit comprises a calibration chamber and at least one standard vacuum gauge; the standard vacuum gauge is connected to the calibration chamber, and the calibration chamber is respectively connected to the inflation unit and the exhaust unit.

8. The fully automatic capacitance film vacuum gauge calibration device according to claim 7, characterized in that: The calibration unit also includes a calibration interface, an air extraction valve and a flow limiting orifice; The calibration interface adopts KF16 interface design; The air extraction valve comprises a pneumatic gate valve and an electromagnetic pressure differential valve; one end of the pneumatic gate valve and the electromagnetic pressure differential valve is connected to the calibration chamber, and the other end of the pneumatic gate valve and the electromagnetic pressure differential valve is connected to the air extraction unit; The flow-limiting orifice is disposed between the pneumatic gate valve and the air extraction unit.

9. The fully automatic capacitance film vacuum gauge calibration device according to claim 8, characterized in that: The air extraction unit comprises a first pump, a second pump, an electromagnetic isolation valve and a pneumatic air release valve; The first pump is connected to the pneumatic gate valve, the other end of the first pump is connected to the electromagnetic isolation valve, the other end of the electromagnetic isolation valve is connected to the second pump, and the other end of the second pump is connected to the electromagnetic pressure differential valve; the pneumatic air release valve is connected to the calibration chamber.

10. A fully automatic capacitance film vacuum gauge calibration device according to any one of claims 1 to 5, characterized in that: The control unit includes an industrial computer, a protocol converter, a PID controller, a digital-to-analog converter, a pressure transmitter and a vacuum gauge controller; the industrial computer is connected to the PID controller and the digital-to-analog converter respectively through the protocol converter, the digital-to-analog converter is connected to the vacuum gauge controller, the inflation unit and the pressure transmitter respectively, and the vacuum gauge controller and the PID controller are connected to the calibration unit.

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