Electromagnetic gaging of elevator rails and other structures
US5373123A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 25, 1993 |
| Grant date | Dec 13, 1994 |
| Priority date | — |
| Expiry date | Oct 25, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/345
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Orthogonal sets (26, 28) of coils (21-24) are each connected for differential response to an alternating magnetic field in a taut wire (20) disposed adjacent a rail (76) in an elevator hoistway. The wire is powered with AC current (34, 38) which is also used (40, 44) to synchronously demodulate the response of the coils to the alternating magnetic field so as to produce an output signal (58, 67) indicative of the position of the coils with respect to the taut wire. The coils may be in a holder (70) which is resiliently urged (72) toward the rail, with the wire passing through a hole therein within the coils, or mounted on an elevator which also has a contactless rail position sensor (110-112). Variation in current adjacent the coils is measured by additively coupling the coils (FIGS. 8, 9) which may be used to compensate the position measured by the coils (FIG. 11). Rectangular coil cross sections, as well as preferred coil spacing and dimensions are shown.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.