| The processes of industrial production and control of the fluid are all related to the pressure measurement and testing. Silicon Differential Pressure Transmitter(SDPT) is a kind of common instrument in the industrial automation control and it is widely used in pressure and differential pressure measurement as well as it also can be applied to measure other parameters such as flow, liquid level and density. With the industrial product of the technological process have been put forward on the accuracy,stabilty, reliability of SDPT to become larger, more complex with the application of automation control. However, the current SDPTs at home have many problems, such as low precision, bulk packaging problems, poor long-term stability, low static pressure capability, the increasing error when overloaded, large temperature error, narrow temperature range, etc. In this research paper, some of work included the structure of the optimal design and establish the mathematical model of static error compensation, have been done to solve the problem of SDPT’s low static pressure capability and large error under high static pressure.Firstly, this paper analyzes the development history and current situation of the development of SDPT, describes four different kinds of differential pressure transmitter(DPT) which designed and manufactured according to different principles, introduces the world’s leading intelligent DPT products with its technical indicators, elaborates the research status of the influence of the static pressure of DPT.The overall design of SDPT, including the working principle of DPT, the measurement principle of differential pressure sensor(DPS), piezoresistive effect, theoretical basis of sensitive chip layout design, silicon differential chip production profile are studied in this paper. A thorough theoretical study about the silicon chip which is the critical part of DPS has been done. Differential pressure, static pressure and static pressure influence of DPS in working conditions are explained in detail. The output of four DPSs under normal temperature and a certain static pressure illustrates the static pressure effect of silicon differential pressure sensor(SDPS), the test results show that the static pressure had significant effect on the output of SDPS.After that, by using the theory of elastic mechanics and theory of shell and plate, stress distribution of rectangular stress membrane is analyzed and deduced, it is concluded that the maximum stress difference between the vertical and horizontal direction occurs in the middle of the square diaphragm, it is not only an indispensable theoretical basis to determine the layout of pressure sensitive resistance on the stress diaphragm, but also needed to determine the stress changes caused by other factors such as structure changes. Finite element analysis(FEA) software ANSYS is used to contrast the stress distribution analysis of the single silicon differential pressure chip with that of the chip installed to the base. Then two optimization plans are proposed in view of the base deformation effect on the stress distribution in silicon differential chip, and according to these plans, the finite element simulation comparison are put into effect, and the second plan is selected to make a real sensor and do the test.Finally, a set of test equipment based on dual channel pressure calibrator is designed, which can be used to SDPT static pressure and differential pressure test, a simple static error compensation method of DPT is put forward by dealing with the test results based on this equipment. This method has good effect to improve the SDPT in precision grades of the production, especially for static error compensation. |
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