Wheel-speed sensor
The wheel-speed sensor comprises a silicon integrated circuit enclosed within the sensor head, sealed with overmolded plastic for hermetic sealing. Bosch wheel-speed sensors utilize Hall technology, integrating the Hall-sensing element, signal amplifier, and signal processing onto a single chip. The circuit is exposed to the changing magnetic field of the rotating encoder, which may be a multipole or a steel wheel. In applications with a steel wheel, a magnet placed inside the sensor is necessary.
The Hall element generates an alternating voltage proportional to the changing magnetic field. This sinusoidal voltage is then processed by the circuit into an alternating digital output signal, with the wheel-speed information transformed into load-independent rectangular current impulses. The frequency of these current pulses is directly correlated with the wheel speed, enabling detection of very low speeds, down to nearly stand-still (0.1 km/h).
For wheel-speed sensors with signal redundancy, designed to meet the demands of highly automated driving, various sensor variants are available (with harness or directly plugged). By utilizing familiar and proven electrical components, the complexity of highly automated driving functions is reduced. Additionally, a continuously available signal at the secondary device ensures minimal latency when switching the actuator.