Apparatus for generating a pulse when a first member passes a second member using permanent magnets with different strengths

US4217512A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Peter Hauler · Karlsruhe, DE
• Wolfgang Bremer · Ettlingen, DE
• Karl-Ernst Weiss · Ettlingen, DE
• Frieder Heintz · Blankenloch, DE

Key dates

• Filing date: Apr 17, 1979
• Grant date: Aug 12, 1980
• Expiry date: Apr 17, 1999

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02N11/004
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A Wiegand wire is placed within the magnetic field generated by a first and second permanent magnet. The first permanent magnet has a field strength exceeding that of the second permanent magnet and the polarity of its magnetic field is opposite that of the second magnet. A rotor having segments of magnetic shielding alternating with slots is rotated between the Wiegand wire and the first magnet. When the magnetic shielding is between the first magnet and the Wiegand wire, the latter is exposed only to the magnetic field of the second permanent magnet. In a second position of the rotor, the Wiegand wire is exposed to both magnetic fields. Since the second permanent magnet generates a stronger field than the first, the direction of magnetization in the Wiegand wire changes abruptly causing a pulse to be generated in pick-up coil 4.