| 摘要 |
PURPOSE:To hold the detection sensitivity constant even in the presence of an external magnetic field and to enable invariably accurate torque sensor by providing a means which applies a DC bias magnetic field to amorphous magnetic metal. CONSTITUTION:When torque T is applied to a shaft 11, amorphous magnetic metal zones 12 and 13 on the shaft 11 are strained as a result. This magnetostrictive effect causes the metal zones 12 and 13 to vary magnetic permeability. Coils 28 and 29 vary in impedance according to said variation and the output of a signal processing part varies corresponding to the value and direction of the torque T to obtain the function of the torque sensor. At this time, a bias magnetic field application source 17 is provided which has magnets 22 and 24 as magnetic field production sources. Those magnets 22 and 24 are magnetized in the same direction as the direction of the shaft 11, and the magnetic flux passes through the path of the magnet 22, a yoke 19, a magnetic pole surface 18, the shaft 11, a magnetic pole surface 20, a yoke 21, the magnet 24, a yoke 23, and the magnet 19. Therefore, the DC bias magnetic field is applied to the metal zones 12 and 13 to hold the detection sensitivity at a constant value. |
