Strain-type pressure sensor is a sensing device, which is a pressure sensor that uses elastic sensitive elements and strain gauges to convert the measured pressure into corresponding resistance changes. According to the structure of elastic sensitive elements, strain-type pressure sensors can be roughly divided into strain There are 4 types: tube type, diaphragm type, strain beam type and combined type.
Features of strain gauge pressure sensor
1. Strain cylinder
The sensor is characterized by high strength and shock resistance, excellent static characteristics, dynamic characteristics and high self-vibration frequency, which can reach more than 30khz, and the measured upper limit pressure can reach 9.6mpa. Suitable for measuring high-frequency pulsating pressure, plus forced water cooling. Also suitable for dynamic pressure measurement at high temperature, such as rocket engine pressure measurement, internal combustion engine, compressor, etc. pressure measurement.
2. Diaphragm
This type of diaphragm strain pressure sensor is not suitable for measuring large pressure. When the deformation is large, the nonlinearity is large. However, in small pressure measurement, the deformation is very small, the nonlinear error can be less than 0.5%, and at the same time, it has high sensitivity. Therefore, in the measurement of shock wave, this type of diaphragm pressure sensor has been used at home and abroad.
3. Strain beam
It is suitable for the measurement of small pressure, and the output signal is not affected by the change of the position of the measuring point. And this sensor has a simple structure, good stability, easy to install and maintain.
4. Strain combination
It is mainly used to measure the dynamic or static pressure of the flowing medium, such as the inlet and outlet of power piping equipment, the pressure of gas or liquid, and the pressure of internal combustion engine piping.
Strain characteristics of pressure sensor
Diaphragm smart pressure sensor has twice the measuring range than inductive sensor. It can not only detect metal targets, but also detect dielectrics such as paper, glass, wood and plastic. It can even be detected through walls or paper shells. Because the human body is equivalent to an electrical conductor at low frequencies, it has also appeared for human tremor measurement and anti-theft alarms.
When measuring the strain of the component, just stick the strain gauge directly to the component, but if you want to measure the force, pressure, acceleration and other signals, you should first convert these physical quantities into strain, and then use the strain gauge to measure, more than when directly measuring There is a conversion process. The original that completes this conversion process is usually called an elastic original. Therefore, the strain sensor is usually composed of an elastic sensitive original and a strain gauge.
The elastic sensitive element is the core component of the sensor, which requires high elastic energy storage of the elastic element, which is usually expressed as the ability of the elastic material to store deformation work without permanent deformation. The pressure sensor has good mechanical processing and heat treatment performance, and has strong compressive strength. Due to characteristics such as small temperature influence, the correct selection of elastic sensitive components and strain gauge bridges is an important way to improve strain sensors:
1. The measuring range has high optical precision. The force sensor can measure the force of 0.01--1000000N, and the accuracy can reach more than 0.05%FS; the pressure sensor can measure the pressure of 0.1-1000000, and the accuracy can reach 0.1%FS.
2. Stable and reliable performance, long service life, such as weighing mechanical lever, due to the friction and friction between the lever and the knife edge, it is quite difficult to maintain its accuracy for a long time. It is made of resistance strain type weighing sensor. Electronic pumps, truck scales, railroad scales, etc., can work stably under harsh environmental conditions for a long time.
3. Excellent frequency response characteristics. The response time of the pressure sensor is generally 0.01MS, and the semiconductor strain gauge can reach 0.001MS. If you can take measures on the elastic element, the strain sensor composed of them can measure the dynamic process of tens of kilohertz or even hundreds of kilohertz.