基于Havar合金膜片的电容式压力传感器研制
发布时间：2018-07-18 16:16
【摘要】：电容式压力传感器因其灵敏度高、温阻效应低以及工作稳定性好,广泛应用于工业自动化检测与监控场所。随着工作环境的日益复杂及恶化,传统的压力传感器显现出很大的局限性。因此,提出了一种采用Havar合金为中心膜片的压力传感器,比传统的不锈钢膜片具有更高的强度和韧性,更优异的抗腐蚀性及抗磁性。通过测量Havar膜片在外部压力作用下的位置变化所产生的电容变化量,可实现小量程压力的检测。本文围绕差压电容式压力传感器的理论基础,制作工艺以及测试进行深入研究与实现。中心膜片是电容式压力传感器的核心部分,其直接影响压力传感器的灵敏度及分辨率。文中应用有限元分析软件ANSYS WORKBENCH,对膜片的工作特性进行理论分析,得到膜片的受力以及形变的二维分布。根据电容两固定极板的间距及最大检测压力,计算出膜片厚度的最小允许值。通过构建膜片中心点的形变与输入压力的特性曲线,先得到膜片灵敏度,再以此为目标函数,以膜片厚度和直径为变量,优化膜片的结构参数,最后采用Havar合金膜片的厚度50μm,直径为Φ26mm。对电容式压力传感器的电容检测电路进行设计,是基于灵敏度等关键技术指标来完成的。采用了振荡器、限幅器、鉴频器和放大器等电路,其核心是C/F转换和F/V转换,将传感器的弱电容信号转换为电压信号。通过对该电路进行了模拟仿真试验,得到较为接近的电压输出信号,验证了此电路能满足电容检测设计要求。同时,对该电路进行优化设计,从而提升了电路的检测性能以及抗干扰能力。最后,确定电容式压力传感器的测试条件以及测试项目,对制作出的工程样机进行了测试,得到压力传感器的校准数据。通过数据分析可以看到,测试结果与膜片的仿真结果较为接近,验证了基于Havar合金膜片的电容式压力传感器检测压力模型的准确性。
[Abstract]:Capacitive pressure sensor is widely used in industrial automatic detection and monitoring because of its high sensitivity, low temperature resistance and good working stability. With the increasing complexity and deterioration of the working environment, the traditional pressure sensors show great limitations. Therefore, a pressure sensor with Havar alloy as the central diaphragm is proposed, which has higher strength and toughness, better corrosion resistance and diamagnetism than the traditional stainless steel diaphragm. The small range pressure can be detected by measuring the capacitance change caused by the position change of Havar diaphragm under external pressure. In this paper, the theoretical basis, fabrication process and test of differential capacitance pressure sensor are studied and realized. Central diaphragm is the core part of capacitive pressure sensor, which directly affects the sensitivity and resolution of pressure sensor. In this paper, the finite element analysis software ANSYS WORKBENCH is used to analyze the working characteristics of the diaphragm theoretically, and the stress and the two-dimensional distribution of the deformation of the diaphragm are obtained. The minimum allowable value of diaphragm thickness is calculated according to the distance between two fixed electrode plates and the maximum detection pressure. By constructing the characteristic curves of deformation and input pressure at the central point of the diaphragm, the sensitivity of the diaphragm is obtained first, then the diaphragm sensitivity is obtained, and the thickness and diameter of the diaphragm are taken as variables to optimize the structural parameters of the diaphragm. The thickness of Havar alloy diaphragm is 50 渭 m and the diameter is 桅 26mm. The capacitance detection circuit of capacitive pressure sensor is designed based on the key technical indexes such as sensitivity. The oscillator, limiter, frequency discriminator and amplifier are used. The core of the circuit is C / F conversion and F / V conversion. The weak capacitance signal of the sensor is converted into voltage signal. Through the simulation and simulation of the circuit, a close voltage output signal is obtained, and it is verified that the circuit can meet the design requirements of capacitance detection. At the same time, the circuit is optimized to improve the detection performance and anti-interference ability of the circuit. Finally, the test conditions and test items of the capacitive pressure sensor are determined, and the calibration data of the pressure sensor are obtained by testing the engineering prototype. Through the data analysis, it can be seen that the test results are close to the simulation results of the diaphragm, which verifies the accuracy of the pressure detection model of capacitive pressure sensor based on Havar alloy diaphragm.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212
本文编号：2132458
[Abstract]:Capacitive pressure sensor is widely used in industrial automatic detection and monitoring because of its high sensitivity, low temperature resistance and good working stability. With the increasing complexity and deterioration of the working environment, the traditional pressure sensors show great limitations. Therefore, a pressure sensor with Havar alloy as the central diaphragm is proposed, which has higher strength and toughness, better corrosion resistance and diamagnetism than the traditional stainless steel diaphragm. The small range pressure can be detected by measuring the capacitance change caused by the position change of Havar diaphragm under external pressure. In this paper, the theoretical basis, fabrication process and test of differential capacitance pressure sensor are studied and realized. Central diaphragm is the core part of capacitive pressure sensor, which directly affects the sensitivity and resolution of pressure sensor. In this paper, the finite element analysis software ANSYS WORKBENCH is used to analyze the working characteristics of the diaphragm theoretically, and the stress and the two-dimensional distribution of the deformation of the diaphragm are obtained. The minimum allowable value of diaphragm thickness is calculated according to the distance between two fixed electrode plates and the maximum detection pressure. By constructing the characteristic curves of deformation and input pressure at the central point of the diaphragm, the sensitivity of the diaphragm is obtained first, then the diaphragm sensitivity is obtained, and the thickness and diameter of the diaphragm are taken as variables to optimize the structural parameters of the diaphragm. The thickness of Havar alloy diaphragm is 50 渭 m and the diameter is 桅 26mm. The capacitance detection circuit of capacitive pressure sensor is designed based on the key technical indexes such as sensitivity. The oscillator, limiter, frequency discriminator and amplifier are used. The core of the circuit is C / F conversion and F / V conversion. The weak capacitance signal of the sensor is converted into voltage signal. Through the simulation and simulation of the circuit, a close voltage output signal is obtained, and it is verified that the circuit can meet the design requirements of capacitance detection. At the same time, the circuit is optimized to improve the detection performance and anti-interference ability of the circuit. Finally, the test conditions and test items of the capacitive pressure sensor are determined, and the calibration data of the pressure sensor are obtained by testing the engineering prototype. Through the data analysis, it can be seen that the test results are close to the simulation results of the diaphragm, which verifies the accuracy of the pressure detection model of capacitive pressure sensor based on Havar alloy diaphragm.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212
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