Different pressure transmitters have different principles. ： The following describes the working principles of several commonly used pressure transmitters :
. 电容式压力变送器 原理 I. Principle of Capacitive Pressure Transmitter
以 及将电容转换成二线制4-20mA电子线路板组成 。 Capacitive pressure transmitters are mainly composed of chamber-sensing components that realize pressure-capacitance conversion, and convert the capacitance into a two-wire 4-20mA electronic circuit board . 者 一侧施加到隔离膜片后，经硅油灌充液传至容室的中心膜片上，中心膜片是个边缘张紧的膜片，在压力的作用下，产生相应的位移，该位移形成差动电容变化 ， 并经过电子线路板的调节、震荡和放大 ， 转换成4-20mA信号输出 ， 输出电流与过程压力成正比 。 When the process pressure is applied to the isolation diaphragm from both sides or one side of the measuring chamber , it is transmitted to the central diaphragm of the chamber through the silicone oil filling liquid. The central diaphragm is a diaphragm with a tight edge. Under the action, a corresponding displacement is generated, and this displacement forms a change in differential capacitance , which is adjusted, oscillated, and amplified by the electronic circuit board, and converted into a 4-20 mA signal output . The output current is proportional to the process pressure .
. 扩散硅压力变送器 原理及应用 Principle and Application of Diffused Silicon Pressure Transmitter
如 不锈钢或 者 陶瓷），使膜片产生与介质压力成正比的微位移，使传感器的电阻值发生变化，和用电子线路检测这一变化，并转换输出一个对应于这一压力的标准测量信号。 The pressure of the measured medium directly acts on the diaphragm of the sensor ( such as stainless steel or ceramic), causing the diaphragm to generate a micro-displacement proportional to the pressure of the medium, changing the resistance value of the sensor, and detecting this change with electronic circuits. , And convert and output a standard measurement signal corresponding to this pressure.
. 陶瓷压力变送器 原理及应用 3. Principle and Application of Ceramic Pressure Transmitter
。 The anti-corrosion pressure transmitter has no liquid transmission. The pressure directly acts on the front surface of the ceramic diaphragm, causing the membrane to deform slightly. Thick film resistors are printed on the back of the ceramic diaphragm and connected to form a Wheatstone bridge . Due to the piezoresistive effect of the varistor, the bridge generates a voltage signal that is highly linear and proportional to the pressure and proportional to the excitation voltage. The standard signal is calibrated to 2.0 / 3.0 / 3.3 mV according to the pressure range. Compatible with strain gage sensors. Through laser calibration, the sensor has high temperature stability and time stability. The sensor has a temperature compensation of 0 ～ 70 ℃, and can directly contact most media. Ceramic is a recognized material with high elasticity, corrosion resistance, wear resistance, shock resistance and vibration. 以 及它的厚膜电阻可以使它的工作温度范围高达-40～135℃，而且具有测量的高精度、高稳定性。 Ceramic's thermal stability and its thick film resistance can make it work temperature range up to -40 ~ 135 ℃, and has high accuracy and high stability of measurement. 大于 2kV，输出信号强，长期稳定性好。 The degree of electrical insulation is greater than 2kV, the output signal is strong, and the long-term stability is good. 高特性，低价格的陶瓷传感器将是压力变送器的发展方向 。 In the future development, high-performance, low-cost ceramic sensors will be the development direction of pressure transmitters .