System and method of perpendicularly magnetizing position information in a magnetically hard layer of a moving component
US7755350B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 2008 |
| Grant date | Jul 13, 2010 |
| Priority date | — |
| Expiry date | Jan 1, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/24476
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A position-sensing system magnetically senses the position of a piston rod moving with respect to a cylinder. A magnetically hard layer on the piston rod provides a recording medium. Information is perpendicularly magnetized in regions of the magnetically hard layer. These regions provide an encoding scheme for determining the position of the piston rod. Magnetic-field sensors are positioned over redundant tracks of magnetically recorded regions. Each magnetic-field sensor positioned over a given track senses the same magnetized regions while the piston rod moves with respect to the cylinder. Other magnetic-field sensors can sense ambient fields for use in performing common-mode rejection. A write head can dynamically repair damaged or erased regions detected by the magnetic-field sensors. Energized by a battery-backup power source, the magnetic-field sensors and associated circuitry can continue to track movement of the piston rod when the machinery is off.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.