PURPOSE: To make it possible to measure the stress in the axial direction of a rail, by differentially connecting magnetic anisotropy detecting coils so that disturbance magnetic fields are offset.
CONSTITUTION: Detecting coils 17-1 and 17-2 of one magnetic anisotropy sensor 15-1 are cumulatively connected. Detecting coils 19-1 and 19-2 of another magnetic anisotropy sensor 15-2 are similarly connected. When the sensors 15-1 and 15-2 are arranged at an equal angle with respect to a rail, the voltages, caused by disturbance magnetic fluxes, which are induced in the detecting coils 17-1 and 17-2 and 19-1 and 19-2, become equal. When the coils 17-1 and 17-2 and 19-1 and 19-2 are differentially connected, the voltages are offset, and no output appears across output terminals 12. When exciting coils 18-1 and 18-2 are connected out of phase, the signal voltages, which are induced in the detecting coils 19- 1 and 19-2 become out of phase. Since the detecting coils 19-1 and 19-2 and 17-1 and 17-2 are differentially connected, the signals are added, i.e., the result is the twice the original voltage. Therefore, the detected signal of the degree of magnetization of the rail by the exciting coils of the sensors themselves becomes twice the original value. The disturbances are offset, and the proper signal can be positively detected.
TAKESHITA KUNIO
ONO TOSHIYUKI
ITOU MASAYUKI
SUGIMURA SHIYUUJI
HITACHI LTD
HITACHI ELECTR ENG