Process for contactless measurement of mechanical stress and device for carrying out the same

US4976160A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Klaus Dobler · Gerlingen, DE
• Hansjorg Hachtel · Rutesheim, DE
• Georg Zimmermann · Gerlingen, DE

Key dates

• Filing date: Jan 20, 1989
• Grant date: Dec 11, 1990
• Expiry date: Jan 20, 2009

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L3/105
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Two regions (11, 12) of a shaft (10) are coated with a film which is free of prestress and consists of magnetoelastic Fe/Ni material. The films have a stripe pattern arranged respectively at angles of +45.degree. and -45.degree.. The change in permeability of these films is a function of the mechanical stress of the shaft (10), particularly of the torsion, and is detected by means of sensor arrangements (13 and 14). A characteristic line for the mechanical stress which extends linearly over the entire range of measurement is made possible by means of an evaluating circuit (22) of the measured voltages.