Revolution, Crankshaft or Camshaft Position Sensors are usually located on a gear wheel (phonic wheel), disks consisting of sectorized windows or rings of ferro- magnetic material. These sensors detect magnetic flux variations which are produced by the alternation between the presence and absence of the teeth of the gear wheel, or the cam relief. The reading of the magnetic flux variations are turned into an electrical signal, which goes directly to the control unit.
Revolution, Crankshaft or Camshaft Position Sensors are usually located on a gear wheel (phonic wheel), disks consisting of sectorized windows or rings of ferro- magnetic material. These sensors detect magnetic flux variations which are produced by the alternation between the presence and absence of the teeth of the gear wheel, or the cam relief. The reading of the magnetic flux variations are turned into an electrical signal, which goes directly to the control unit and checks, depending of the sensor, the following aspects:
This type of sensors, also known as Timing and Revolution Sensors, are divided by FAE into 2 groups:
The sensor consists of a pickup coil, a magnetic core and a permanent magnet and is mounted in front of a gear wheel. As the teeth of the gear wheel (or other target features) pass by the face of the magnet, the amount of magnetic flux passing through the magnet and consequently the coil varies. When the gear tooth is close to the sensor, the flux is at a maximum. When the tooth is further away, the flux drops off. The moving target results in a time-varying flux that induces a proportional voltage in the coil which varies in function of the speed rotation and the distance to the gap in both frequency and amplitude. These variations cause the signal we receive as follows:
The sensor consists of a semiconductor sensor combined with an electronic circuit that protects the sensor from possible voltage peaks and a permanent magnet. The operating principle is based on the so-called Hall Effect, the production of a voltage difference (the Hall voltage) across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current. The response we get from the sensor is a U wave which is proportional to the variations detected by the sensor. These variations cause the signal we receive as follows:
Variable Reluctance Sensor
Hall Effect Sensor
The specific values of the sensors must be checked each maintenance or every 25.000km. Replace the sensor whenever results are diagnosed which are not within the specified operating limits.
Replace the gasket each time the sensor is changed. The gaskets do not perform their sealing function if these are used or worn.
