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压力变送器工作原理

Working principle of pressure transmitter

压力变送器用于测量液体、气体或蒸汽的液位、密度和压力，然后将压力信号转变成4-20mADC信号输出。主要有电容式压力变送器和扩散硅压力变送器，陶瓷压力变送器，应变式压力变送器等。

The pressure transmitter is used to measure the liquid level, density and pressure of liquid, gas or steam, and then converts the pressure signal into 4-20madc signal output. There are mainly capacitive pressure transmitter and diffusion silicon pressure transmitter, ceramic pressure transmitter, strain type pressure transmitter and so on.

介质压力直接作用于敏感膜片上，分布于敏感膜片上的电阻组成的惠斯通电桥，利用压阻效应实现了压力量向电信号的转换，通过电子线路将敏感元件产生的毫伏信号放大为工业标准信号。

The dielectric pressure acts on the sensitive diaphragm directly. The Wheatstone bridge composed of the resistance distributed on the sensitive diaphragm realizes the conversion of pressure to electrical signal by using piezoresistive effect, and the millivolt signal generated by the sensitive element is amplified into the industrial standard signal through the electronic circuit.

电容式

Capacitive type

当压力直接作用在测量膜片的表面，使膜片产生微小的形变，测量膜片上的高精度电路将这个微小的形变变换成为与压力成正比的高度线性、与激励电压也成正比的电压信号，然后采用专用芯片将这个电压信号转换为工业标准的4-20mA电流信号或者1-5V电压信号。

When the pressure directly acts on the surface of the measuring diaphragm, the diaphragm will produce tiny deformation. The high-precision circuit on the measuring diaphragm transforms the tiny deformation into a voltage signal which is directly proportional to the pressure and is also proportional to the excitation voltage. Then, the voltage signal is converted into the industrial standard 4-20mA current signal or 1-5V voltage signal by using a special chip.

由于测量膜片采用标准化集成电路，内部包含线性及温度补偿电路，所以可以做到高精度和高稳定性，变送电路采用专用的两线制芯片，可以保证输出两线制4-20mA电流信号，方便现场接线。

Since the measuring diaphragm adopts standardized integrated circuit, including linear and temperature compensation circuit, it can achieve high precision and high stability. The transmission circuit adopts special two-wire chip, which can ensure the output of two-wire 4-20mA current signal, which is convenient for field wiring.

扩散硅

Diffused silicon

被测介质的压力直接作用于传感器的膜片上（不锈钢或陶瓷），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 acts directly on the diaphragm of the sensor (stainless steel or ceramic), which makes the diaphragm produce a micro displacement proportional to the pressure of the medium, changes the resistance value of the sensor, and detects the change with an electronic circuit, and converts and outputs a standard measurement signal corresponding to the pressure.

陶瓷

ceramics

压力直接作用在陶瓷膜片的前表面，使膜片产生微小的形变，厚膜电阻印刷在陶瓷膜片的背面，连接成一个惠斯通电桥（闭桥），由于压敏电阻的压阻效应，使电桥产生一个与压力成正比的高度线性、与激励电压也成正比的电压信号。

The pressure directly acts on the front surface of the ceramic diaphragm, which makes the membrane produce tiny deformation. The thick film resistor is printed on the back of the ceramic membrane and connected to a Wheatstone bridge (closed bridge). Due to the piezoresistive effect of varistor, the bridge produces a voltage signal which is highly linear and proportional to the excitation voltage.