Method for measuring the rotor angle-based expansion of a rotating rotor under centrifugal stress

A method for measuring the expansion of a rotating rotor on the basis of the rotor rotational speed in which a first distance sensor is arranged at a basic distance from the rotor surface and contactlessly detects the distance between the rotor surface and the first distance sensor in a time-based manner, and generates time-based electric first distance signals,

• a zero mark sensor is assigned to the rotor that scans zero marks applied onto the rotor and generates time-based electrical zero mark signals,
• wherein the time-based electric first distance signals and the time-based zero mark signals are fed to an electrical evaluation device and processed thereby by calculating a rotational speed and a rotational angle assigned to each instant of a rotor rotation from the zero mark signals, and each rotational angle assigned to an instant is combined with the simultaneous distance signal into a rotational angle-related distance signal, and an expansion of the rotor dependent on the rotational angle and the rotational speed is calculated therefrom,
• wherein a second distance sensor is arranged at a basic distance from the reference surface on a first reference surface which is remote from the first distance sensor in the axial direction of the rotor and of which the expansion and surface profile are known, said second distance sensor contactlessly detecting the distance of the reference surface from the second distance sensor in a time-based manner and generating time-based electrical second distance signals which are supplied to the electrical evaluation device,
• wherein a third distance sensor is arranged at a basic distance from the second reference surface on another second reference surface which is remote from the first and second distance sensors in the axial direction of the rotor and of which the expansion and surface profile are known, which third distance sensor detects the distance between the reference surface and the third distance sensor in a time-based manner without contact and generates time-based electrical third distance signals that are supplied to the electrical evaluation device which processes the second and third distance signals to correct the first distance signals detected by the first distance sensor, and
• wherein, after subtracting the known expansion and profile of the surface from the second and third distance signals, the interference oscillations remaining therein are geometrically removed proportionally from the first distance signal of the first distance sensor by using trigonometric methods.