Vehicle Speed Sensor

Features

It is used quantify the mechanical vehicle speed to electrical signal by reading a drum or tone wheel rotation and conveyed to a remote computer module. The module uses the signal to establish an inhibitive vehicle speed value. The sensor shall provide a quasi-sinusoidal A/C signal whose frequency and voltage are proportional to the vehicle speed and generate only one cycle for each pass across one tooth of the drum or tone wheel. This sensor must be capable of operating over a temperature range of 40 to 140degree Celsius and vehicle driveline vibration.

- Hall Effect Sensor
This sensor responds to the presence or the interruption of a magnetic field by producing either a digital or an analog output proportional to the magnetic field strength. Digital and analog "sensor-only" devices are operated by the magnetic field from a permanent magnet or electromagnet. Actuation mode depends on the type of magnets used. It is operating either a vane passing through a gap or a magnet mounted on a plastic plunger.

-Inductive Sensor
The internal construction of the sensor is a magnet, pole piece and coil.
A magnetic field (lines of flux) extends from the magnet, through the pole piece and coil out into the air space at the end of the sensor. The return path of the magnetic field is from the air space to the other end of the magnet. As a ferrous object approaches the tip of the pole piece, the magnetic field increases and then decreases as the object moves away from the pole piece. The snap or the rapid change in the magnetic field induces an AC voltage signal in the coil. With an ideal target and matching sensor, the induced voltage is in the shape of a sine wave. As can be seen, the generated frequency signal is directly proportional to the number of ferrous objects passing the pole piece per unit time. The amplitude of the voltage output is proportional to the speed of the ferrous objects passing the pole piece.