Temperature compensated magnetic damping assembly for induction meters

A magnetic damping assembly for an induction device magnetically driving an electroconductive disk, said assembly comprising:

• a pair of permanently magnetized pieces of anisotropic material, each of said pieces having an easy axis of magnetization, said pieces each having two magnetized regions of opposite polarity, said regions providing two easy flux paths parallel to said easy axis of magnetization and separated by a dead zone of unmagnetized anisotropic material, each of said easy flux paths defining a north and a south pole, said pieces being juxtaposed about a predetermined space through which said disk rotates such that said easy flux paths of each of said pieces are perpendicular to said disk and aligned so that the magnetic flux passes twice through said disk in opposite directions;
• a pair of flux return plates formed of a soft magnetic material, one of said plates being located adjacent to each of said pieces so as to provide a series flux path parallel to said disk and linking said two easy flux paths;
• and
• means for varying the position of at least one of said flux return plates relative to said adjacent piece so as to vary the magnetic flux linked between said two easy flux paths of said piece thereby varying the damping;
• and
• at least one temperature compensating member extending between said north and said south poles, across said dead zone, of one of said pieces thereby providing a shunt flux path, said temperature compensating member having a permeability that varies with temperature.

A permanent magnet assembly, comprising:

• two pieces of anisotropic magnetic material, each of said pieces comprising two magnetized regions of opposite polarity with an unmagnetized dead zone therebetween, said pieces being disposed in cooperative association to define a gap between them, said two magnetized regions of said two pieces being associated to define two positions within said gap, each of said positions having magnetized regions of opposite polarity disposed proximate each other on opposing sides of said gap;
• a first flux return member disposed adjacent to a first one of said two pieces, said first one piece being disposed between said first flux return member and said gap, said first flux member providing a flux path between said two magnetized regions of said first one piece;
• a second flux return member disposed adjacent to a second one of said two pieces, said second one piece being disposed between said second flux return member and said gap, said second flux return member providing a flux path between said two magnetized regions of said second one piece;
• and
• means for moving said second flux return method in relation to said second piece in a direction parallel to said gap.