TORQUE SENSOR

PURPOSE:To realize a torque sensor having a good time. characteristic to a wide range of torque and generating no exfoliation of a magnetostriction alloy, by heat treating a magnetic alloy having magnetostriction so as to impart a spiral winding habit thereto to wind the same around a torque transmitting shaft. CONSTITUTION:A magnetic alloy thin strip 2 having magnetostriction is spirally wound around a round rod 6 having an outer diameter r1 smaller than the outer diameter R of the hollow part of a torque transmission shaft 1 and inserted in a cylinder 7 to be provided with a winding habit by heat-treatment. A part of the torque transmission shaft is made hollow and a spiral slit 5 is formed thereto. When the thin strip 2 is wound around the hollow part of the transmission shaft 1, said strip 2 becomes a semi-fixed state and, even when no torque is applied to the transmission shaft 1, a tensile force applied state is obtained. When torque is applied to the transmission shaft 1 in a forward direction, the outer diameter R of the spiral part of the transmission shaft 1 becomes small and the tensile stress generated in the thin strip 2 is relaxed and the magnetic permeability of the thin strip 2 is changed. When torque is applied in the reverse direction, the magnetic permeability of the thin strip 2 is changed in the reverse direction and these changes can be detected in the form of the change in the inductance of an inductance detection coil 3.