Pressure sensors

Pressure sensors are the sensors that detect the air pressure in the vehicle’s intake and convert it into an electrical signal, which is then sent to the control unit so the stoichiometric mixture or air-fuel mixture can be regulated.

The importance of these sensors lies in the fact that at higher altitude, with respect to sea level, there is less oxygen in the air. Consequently, the control unit needs to recalculate the amount of fuel injected so it can maintain a balance between the air in the engine and the amount of fuel supplied. This ensures that the emission of pollutants remains within the regulations and the power of the engine is the same at any altitude. Some sensor models incorporate an NTC type temperature sensor which allows the sensor to detect, not only the pressure, but also the air temperature in the intake. This information is necessary for the control unit to calculate the aspirated air mass and thus regulate the air-fuel mixture.

Pressure sensors must operate in critical installation conditions, they must be capable of operating at temperatures between -40ºC and +120ºC and also be resistant to hydrocarbons. To make this possible, FAE subjects its pressure sensors to exhaustive approval tests that include:

- Cyclic operation at high and low pressure in extreme environmental conditions.
- Resistance to vibrations and to impacts.
- Overpressure operation at low and high temperature.
- Resistance to damp and temperature.
- Thermal shock -40 to 150ºC.

During assembly, all our sensors are subjected to leak-tightness tests and to output voltage checks. Pressure sensors are located directly in the intake manifold or
connected to it by means of a flexible pipe.

Pressure sensors are classified into:
1. Intake manifold pressure sensor: These measure vacuum ranges between 10 and 130 kPa, they are found in vehicles with naturally aspirated engines.
2. Boost pressure sensor: These measure boost pressure ranges of 10-130 kPa ≤ P2 ≥ 400 kPa. They are fitted in turbocharged engines. The use of this type of sensor is very common in vehicles with a variable geometry turbocharger (VGT), as they allow the control unit to measure and control the amount of compressed air in the intake pipe.
3. Brake booster pressure sensor: In contrast to the pressure and boost pressure sensor, the function of the brake booster pressure sensor is to inform the engine control unit if the vacuum in the brake booster is sufficient for it to operate correctly. If the vacuum is not within range, the control unit will change the position of the butterfly valve. The unit will close it to increase the vacuum generated by the engine and the vacuum in the brake booster will move into the permitted parameters.