| 摘要 |
PURPOSE:To increase the sensitivity of a torque sensor and to reduce its size by providing 1st and 2nd soft magnetic magnetism converging layers to the outer peripheries of 1st and 2nd detection coils of the torque sensor. CONSTITUTION:A soft magnetic body is wound around the periphery of a 1st magnetic permeability variation detection layer 8 arranged while surrounding a 1st thin and long magnetic layer 5 having a prescribed angle to a shaft 1 while a gap is left, thus providing the 1st magnetism converging layer 10. Similarly, a 2nd detection layer 9 and the 2nd magnetic converging layer 11 are provided while surrounding a 2nd magnetic layer 6 arranged symmetrically with the magnetic layer 5. Pieces of magnetic flux Fs, Feff, and Fg produced by the detection layers 8 and 9 pass through the layers 10 and 11 unless the converging layers 10 and 11 are saturated. Consequently, the magnetic resistance Ry of the converging layers 10 and 11 is inserted equivalently in parallel to a magnetic resistance Rex. Therefore, Ry<<Rex, so I (Reff<-1>+Rs<-1>+Rg<-1>)E, so large magnetic flux is obtained with the same magnetomotive force, the magnetic layers 5 and 6 are increased in magnetic flux density, and the variation rate of the Reff is made large to increase the variation of the total magnetic flux, thereby increasing the torque sensitivity. Further, the gap (d) to a magnetic shield 12 is made small and the sensor unit is reduced in size.
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