Method and device for accurately determining the distance of a magnetic sensor from a conductive reaction rail

US4812757A · kind A · utility

Assignee

• Thyssen Industrie AG · DE

Inventors

• Jürgen Meins · Baldham, DE
• Helmut Grosser · Maisach, DE

Key dates

• Filing date: Nov 5, 1986
• Grant date: Mar 14, 1989
• Expiry date: Nov 5, 2006

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B7/023
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In magnetic bearings and magnetic suspension devices, sensors (4), as they are used for bearing regulation of support and guide magnets in magnetic transportation technology, continuously measure the distance of a magnet (6) from a reaction rail (7), in order to obtain a signal with which the magnet (6) is controlled with regard to the energizing current in such a way that it remains suspended at the predetermined distance. In known devices, there is no accurate monitoring of the sensor signal, which can result in faulty regulation of the excitation if the sensor signal is faulty, which represents a significant safety risk. Accurate monitoring of the sensor function, in addition to the distance measurement, is acheived by having, in addition to the measurement coil (1) to which alternating voltage is applied, a second reference coil (2), which has only a slight magnetic coupling with the rail (7) and to which the same voltage as the measurement coil is applied, and that the difference current of the two coils is used to measure the distance and the difference current when an additional impedance is periodically switched in is used to check the device.