Magnetic passive position sensor (MAPPS)

A reliable fuel level indicator makes for more relaxed driving. Since they are in an aggressive environment immersed directly in fuel, conventional level sensors with a thick-film network are subject to excessive wear. This can lead to imprecise measurements and cause vehicles to unexpectedly run out of gas. With our Magnetic Passive Position Sensor (MAPPS), we offer an intelligent and long-lasting alternative. The sensor, approximately 4 cm long, is encapsulated when it is mounted in the tank. All important parts are therefore protected from contacting fuel and cannot fail because of contamination. The interior of the MAPPS basically consists of 52 flexible adjacent metal tongues, similar to piano keys. The lever moved by the float is connected to a 2 mm magnet. When the tank is full, the float is on top along with the magnet. As the fuel level falls, it slowly descends and the magnet changes its position correspondingly. The magnet is affixed so close to the sensor that it attracts the metal tongues. The tongues contact a metal strip whose contact site corresponds to a characteristic electrical resistance. From this resistance, the system directly reads the fuel level.