Temperature compensated magnetic damping assembly for induction meters.

摘要

The invention provides a magnetic damping assembly (22) for providing a braking torque on an electro-conductive disk (14) of an induction device. A pair of permanent magnets (26, 27) each has an easy axis of magnetization and provides two easy flux paths parallel to the easy axis of magnetization separated by a dead zone. The permanent magnets are juxtaposed about a predetermined space through which the disk rotates such that the easy flux paths are perpendicular to the disk. The permanent magnets are aligned such that the magnetic flux passes twice through the disk in opposite directions. Flux return members (29, 31) are provided adjacent to each of the permanent magnets so as to provide a flux path parallel to the disk and linking the twa easy flux paths of each of the permanent magnets to provide a highly-efficient, substantially square magnetic flux loop. One of the flux return members (31) is movable relative to the adjacent permanent magnet so as to provide series adjustment of the damping torque. A temperature sensitive magnetic shunting member extends from the north to the south pole, across the dead zone, of each of the permanent magnets so as to provide temperature compensation.