Luftkernesensorer

Luftkernesensorer, also known as air-core sensors, are sensors that use a coil without a ferromagnetic core as the sensing element. They are used to measure position, displacement, or magnetic fields and can be implemented in linear or rotary configurations.

Principle: Because the magnetic core is air, the flux is not concentrated in a permeable material. This yields negligible hysteresis and a wide linear operating range, but also lower magnetic coupling. In practice, these sensors detect changes in inductance or mutual inductance between excitation and sense windings, or between a moving magnet and surrounding coils. The output is typically proportional to the relative position or field strength, requiring signal processing to translate to a position or field measurement.

Design and performance: The absence of a ferromagnetic core reduces saturation and temperature sensitivity due to magnetic history, but it also reduces signal amplitude. This often demands higher excitation currents, larger coil geometries, or more sensitive electronics. Noise, parasitic capacitance, and mechanical tolerances influence accuracy.

Applications: Luftkernesensorer are used in non-contact displacement and position sensing, particularly in linear actuators, optical or magnetic encoders, robotics, and automotive systems where a wide linear range and fast response are advantageous.

See also: Inductive sensor, Hall-effect sensor, mutual inductance, rotary encoder.