ROTARY SENSOR PACKAGING STRUCTURE

PROBLEM TO BE SOLVED: To restrain eddy current loss by supporting an electromagnetic pick-up type rotary sensor penetrating a mounting hole in a metal support so that the most part of a built-in magnet approaches the inside of the support from the thickness center thereof. SOLUTION: An O-ring for a seal is fitted on the outer peripheral surface of a rotary sensor 21. The rotary sensor 21 penetrates a rotary sensor mounting hole 31 provided in a metal support 30 from the outer side 30A side toward the inner side 30B to be fixed to the support 30 with a mounting bolt 33. Then, the position of a magnet 24 built in the fixed rotary sensor 21 is adapted to approach the inner side 30B rather than the outer side 30A. The end face of non-pole piece 23 side of the magnet 24 is disposed to approximately coincide with the center A of the thickness of the support 30 so that the end face of a pick-up coil 26 at the opposite side to the tip 23A of the pole piece is disposed to coincide almost with the inner side 30B. Thus, the magnetic resistance between the tip 23A of the pole piece and the magnet 24 is reduced, so that the output efficiency can be improved.