Speed captor for moving object, comprises a magnetic singularity on part of the moving object which moves between annular windings which have a permanent magnet in their magnetic circuit

摘要

The moving object (9) typically valve gear, moves between ring windings (20,21) with permanent magnets (22,23) in their magnetic circuits (30) which are completed by pole pieces (24,25) and the object. The object has a magnetic insert (27) which varies the reluctance of the magnetic paths and the permanent magnets/coil connections are arranged to signal coil differences which are measured (32,33) at fixed time intervals