| 摘要 |
PURPOSE:To achieve accurate measurement of a transmission torque with the sensitivity and an offset component of a magnetic sensor kept constant, by performing a demagnetization processing of a rotary magnetic body after the generation of a turbulent magnetic field so as to make the magnetization thereof zero. CONSTITUTION:A torque detector uses a magnetic sensor 12 arranged facing a torque transmission shaft 10 separately to detect magneto-striction generated within the transmission shaft 10. A driving circuit 30 connected to an excitation coil 16 of the magnetic sensor 12 applies a symmetrical AC waveform voltage to the excitation coil 16 as outputted from an oscillator to causes an alternating magnetization of the torque transmission shaft 10. The magnetic sensor 12 detects magneto-striction generated within the torque transmission shaft 10 during the application of a torque as electromotive force to be outputted to a detection signal processing circuit 32. A demagnetizing coil 40 is arranged separately facing the torque transmission shaft 10 to return the torque transmission shaft 10 magnetized by a turbulent magnetic field to the zero magnetization. An attenuated vibration current is supplied to the demagnetizing coil 40 from an attenuated vibration current generation source 44 with a demagnetizing circuit 42 formed. |
