| 摘要 |
<p>The invention relates to an inductive proximity sensor for embedding in a mild steel mounting plate (2), comprising an enclosure with a front wall (16) of synthetic material forming a sensing face (4) at a front end of the enclosure, an oscillator (10) comprising a sensor coil (7) with a core (9) made of a material with a relative magnetic permeability larger than 1, typically a ferrite, which is arranged within the enclosure behind the front wall so that an open side of the core (9) is directed towards the sensing face (4) in order to direct the magnetic field of the coil towards a target (6) in front of the sensing face (4), a hollow cylindrical metal member (3) arranged perpendicular to the sensing face (4) and surrounding the core (9), and a measuring circuit (11) for measuring an attenuation of the oscillator (10) due to eddy currents. The core (9) is radially surrounded by a metal layer with a low electrical resistivity cf less than 15 µΩ·cm and with a thickness of less than 40 µm, in order to improve the embeddability of the sensor. Alternatively, this thin metal layer may be omitted, if the electrical resistivity of the metal member (3) is adjusted to a value in the range of 15 µΩ·m - 50 µΩ·cm.
</p> |
