In the automotive electronics industry, automotive sensors are used as information collection sources, mainly used in powertrain systems, body control systems, and chassis systems. They mainly include 8 types of sensors with different functions: pressure sensors, position sensors, temperature sensors, acceleration sensors, Angular velocity sensor, flow sensor, gas concentration sensor and wheel speed sensor.
Pressure sensors are widely used in the automotive industry, and technology is developing rapidly. The pressure sensors currently used in the automotive sensor market are mainly divided into two categories: capacitive pressure sensors and resistive pressure sensors according to the mainstream technology of pressure-sensitive components.
1. The principle of the capacitive pressure sensor
The ceramic capacitor pressure sensor uses a ceramic diaphragm as a pressure-sensitive element. The ceramic diaphragm and the ceramic substrate are respectively made into the two poles of the capacitor. When external pressure acts on the ceramic diaphragm, the ceramic diaphragm is deformed and the distance between the two poles changes, resulting in a change in capacitance, and then through a specific ASIC conditioning chip to output a standard voltage signal
The main application of capacitive pressure sensors in the automotive industry
Ceramic capacitor technology has the advantages of moderate cost, good corrosion resistance, and strong media compatibility. Pressure sensors using ceramic capacitors as pressure-sensitive components are widely used in pressure detection of water, gas, and liquid media, especially for automobiles System (Table 1) Harsh working environment.
2. Principle of the resistance pressure sensor
The resistive pressure-sensitive element uses sputtering or micro-melting glass to consolidate the strain resistance on the elastic diaphragm to form a Wheatstone bridge. When external pressure acts on the elastic diaphragm, the diaphragm is deformed and the resistance value of the strain resistance changes, which causes the Wheatstone bridge to change, and then through the specific ASIC conditioning chip, the standard voltage signal is output.
Resistive pressure sensors use the piezoresistive effect of strain resistance. With the popularization of MEMS technology, according to the material type of the elastic diaphragm and the packaging method of the strain resistance, it can be divided into ceramic resistance type, sputtering film type, silicon strain gage type and 4 types such as silicon piezoresistive type.
Resistive technology has the advantages of small size, wide range, and good temperature consistency. Resistive pressure sensors are widely used in the pressure detection of water, gas, and liquid media, and are especially suitable for the harsh working environment of automotive systems.