Pressure sensors, as commonly used sensors, are widely applied in various industrial automation control environments, including petrochemicals, oil wells, power, shipbuilding, machine tools, pipelines, water conservancy and hydropower, production automation, railway transportation, intelligent buildings, and aerospace. There are various types of pressure sensors and different application environments. What are the different types of pressure sensors? What are their functions?
I. Types of Pressure Sensors
There are five common types: piezoresistive strain gauges, piezoelectric strain gauges, electromagnetic strain gauges, capacitive strain gauges, and vibrating wire strain gauges. Since each instrument has its own advantages and applicable environments differ, the selection should be based on instrument parameters, equipment type, power supply and signal, measurement scale, interface, and other data. Ceramic pressure sensors are based on the piezoresistive effect. Pressure acts directly on the front surface of the ceramic diaphragm, causing minute deformation of the diaphragm. A thick-film resistor is printed on the back of the ceramic diaphragm and connected to a Wheatstone bridge. Due to the piezoresistive effect of the piezoresistive resistor, the bridge produces a high linearity proportional to both pressure and excitation voltage. Standard signal settings are 2.0/3.0/3.3 mV/V, compatible with strain sensors, depending on the pressure range.
II. Types and Functions of Pressure Sensors
1. Sapphire pressure sensor
Sapphire pressure sensors operate on the principle of strain gauges, using silicon sapphire as the semiconductor sensor, and possess excellent measurement characteristics. Semiconductor sensing elements made of silicon sapphire are insensitive to temperature changes and exhibit good operating characteristics even at high temperatures; sapphire has strong radiation resistance; furthermore, silicon sapphire semiconductor sensors do not exhibit pn drift.
2. Intake pressure sensor
The intake manifold pressure sensor detects the absolute pressure downstream of the intake valve. Based on engine speed and load, it detects changes in the absolute pressure in the manifold, converts this into a signal voltage, and sends it to the engine control unit (ECU). The ECU controls the basic fuel injection quantity based on this signal voltage. There are many types of intake manifold pressure sensors, including capacitive and pressure-sensitive types. Due to their small size, flexible installation, fast response time, and high detection accuracy, they are widely used in D-type fuel injection systems.
3. Manifold Absolute Pressure (MAP) Sensor
The intake manifold absolute pressure sensor, located near or inside the vehicle's intake manifold, continuously measures the power load on the engine. The sensor compares these measurements to a vacuum level to ensure consistency. In applications, the MAP sensor is crucial because external factors reported by it can lead to increased engine load and fuel flow demand. For example, if the vehicle begins climbing a hill, the intake manifold absolute pressure sensor should display low vacuum and high engine load.
What types of pressure sensors are there? What are their functions? Conclusion: Because they are frequently used in our lives, we need to have a certain understanding of them, especially since improper operation can easily lead to equipment damage.
