Views: 1 Author: Site Editor Publish Time: 2022-04-18 Origin: Site
Pressure sensor is the most commonly used sensor, which is widely used in various industrial automation environments, involving water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military, petrochemical, oil wells, electricity, ships, machine tools, pipelines, etc. According to different working principles, pressure sensors can be divided into the following types:
High-performance single-crystal silicon pressure sensor, using electromagnetic excitation and electromagnetic vibration pickup, the output is frequency signal, strong anti-interference ability, good stability, no need for A/D conversion, can measure both absolute pressure and differential pressure .
Capacitive transmitters have a variable capacitance sensing component. The sensor is a completely closed assembly. Process pressure, differential pressure is transmitted to the sensing diaphragm through the isolating diaphragm and filling liquid silicone oil to cause displacement. The capacitance difference between the sensing diaphragm and the two capacitor plates is converted into an electrical signal output by a two-wire system of (4-20) mA by electronic components.
Diffusion silicon pressure sensor is that the external pressure is transmitted to the sensitive chip through the stainless steel diaphragm and the inner sealed silicone oil, and the sensitive chip does not directly contact the measured medium. With its high sensitivity output, good dynamic response, high measurement accuracy, good stability, easy to miniaturize, but easily affected by temperature, it is the first choice for mid-range sensors for all measurements greater than 1kpa. Ceramic is recognized as a highly elastic, corrosion-resistant, wear-resistant, shock- and vibration-resistant material.
The thermal stability characteristics of ceramics and its thick film resistance can make its working temperature range as high as -40 ~ 135 ℃, and it has high precision and high stability of measurement. The degree of electrical insulation is >2kV, the output signal is strong, and the long-term stability is good. Has excellent linear accuracy, hysteresis and reliability, cost-effective. In principle higher ranges are also easier to achieve. These two sensors are widely used in aerospace, aviation, navigation, petrochemical, power machinery, biomedical engineering, meteorology, geology, seismic measurement and other fields.
In addition, the sensors used in general pressure transmitters (different from differential pressure transmitters) are commonly used: diffused silicon sensors, ceramic piezoresistive sensors, ceramic capacitive sensors, single crystal silicon sensors, etc.
This kind of sensor can only measure gauge pressure or absolute pressure. They also have their own shortcomings. The sensors used in different occasions are also different. For example, a general small-range pressure transmitter needs to use a ceramic capacitive sensor. The stability and accuracy will be higher than others; and the general ultra-large range, due to the limitation of the production process, usually uses ceramic piezoresistors; for diffused silicon sensors, general oil-filled diffused silicon sensors are more suitable for temperature compensation, etc. The technology has been improved, and it is also outstanding in terms of stability and overload capacity. The differential pressure sensor is filled with silicone oil or inert gas, which is generally a capacitive sensor. Of course, sensors of other technologies are also filled with inert liquid or inert gas. Its function is to apply the pressure evenly to the pressure-sensitive diaphragm.