| Pressure instrument is widely used in industrial production of measuring equipment,after a period of use in order to verify whether it is still accurate and reliable need to be verified.In the field of pressure measurement verification,the specifications and types of pressure gauges submitted are various,and the metrology institute mostly relies on manual pressure regulation detection.The operation process cannot be traced,the subjectivity is strong,it is difficult to review,and the detection accuracy of pressure gauges is low and the efficiency is not high.Therefore,aiming at the detection process of medium and low range pressure instrument,it is the work goal of this topic and the expectation of many measurement units to use automatic pressure generation system to provide high precision specified standard pressure and promote efficient verification.According to the needs of cooperative metrology Institute,this topic develops a highprecision gas pressure generation system applied to pressure instrument detection.The main research contents and achievements are as follows:(1)Overall design and prototype construction of pneumatic generation system.Firstly,according to the actual working condition,process,function and index requirements of pressure gauge verification,the mechanical composition,working principle and process are defined.Then,the modular design of the pneumatic generation system was carried out.Solidworks was used to conduct three-dimensional modeling of the high-precision pressure source of the gas medium,and the manufacturing and selection of pneumatic parts,standard parts and components of the control system were carried out.Finally,the device is built according to the gas path layout,and the voltage regulation test verifies that its performance can meet the daily verification requirements of metrology institute.(2)Research on pressure characteristics of pneumatic generation system and optimum parameter combination of pneumatic parts.AMESim is used to study the influence of component parameters on the pressure characteristics of the pneumatic generation system,and the relevant laws are obtained by simulating the pressure process under different influencing factors.Through the above research,it is found that the inner diameter of the cylinder,the diameter of the gas pipeline,the initial pressure,and the volume of the gas storage tank all have an impact on the pressure building characteristics.Through the orthogonal experimental design method,the key parameters are analyzed,and the significance degree and significance probability of the influence on the pressure efficiency are obtained,so as to determine the optimal parameter combination.(3)Research on Pressure Control Algorithm of pressure gauge.Firstly,a test system was built,and PID control algorithm was used to adjust the pressure.It was found that the pressure control linearity was good in the fine tuning stage before the pressure was about to be verified,but the stability time was long.Therefore,the fuzzy PID control algorithm of EKF prediction is proposed to linearize the fine-tuning stage to shorten the fine-tuning time.The simulation results show that,compared with conventional PID and fuzzy PID control,the algorithm can effectively shorten the fine-tuning time and avoid the generation of overshoot,which meets the design requirements.(4)Pressure feeding accuracy test of physical prototype tester.The source of the uncertainty was analyzed and evaluated,and the influence degree of each factor in the detection process was obtained.The physical prototype was used to carry out the actual gauge test,and a variety of pressure gauges in the measuring range of-0.1～6 MPa were verified.The results show that there is no pressure overshoot phenomenon and the pressure building accuracy meets the design requirements,which is superior to manual in efficiency and accuracy,verifying that the prototype gauge has good substitutability,applicability and high efficiency. |
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