Device for the contactless indirect electrical measurement of a mechanical quantity

摘要

A device for the contactless indirect electrical measurement of a mechanical quantity on a moving sensing object having soft-magnetic properties consisting of a sensor system which is arranged opposite the sensing object with a distance forming an air gap and which comprises a pot-shaped housing with soft-magnetic properties, at least one permanent magnet arranged located adjacently to the sensing object at one end in the housing and at least one sensor arranged at the other end in the housing and having electrical connections, and an evaluating circuit into which the sensor is integrated via the connections, is described in which the sensor is constructed as a capacitor element filled with a polar ferrous fluid between its two electrodes, to the electrodes of which a constant-frequency alternating electrical field can be applied via the connections from the evaluating circuit, on which field the constant magnetic field of the permanent magnet is superimposed, the electrical permittivity of the ferrous fluid being modulated by a change, produced if the air gap changes, of the magnetic flux in the magnetic control circuit formed by the permanent magnet, the air gap, the sensing object and the housing, and the change in modulation generates a signal analogous to this change in the evaluating circuit.