Patent ID: 7387034

Claim:
A torque detecting apparatus comprising: a permanent magnet fixed to a first shaft; a pair magnetic yokes fixed to a second shaft coaxially connected to said first shaft via a connecting rod and disposed within a magnetic field of said permanent magnet to form a magnetic circuit; a pair of flux condensing rings magnetically connected to said magnetic yokes so as to induce a magnetic flux from said magnetic yokes, each said flux condensing ring having a flux condensing portion for condensing the induced magnetic flux; and a detector for detecting a magnetic flux generated between said magnetic yokes, induced by said pair of magnetic yokes and condensed in the flux condensing portions when a torque is applied to said first shaft or said second shaft; whereby the torque applied to said first shaft or said second shaft is detected based on the magnetic flux detected by said detector; wherein said permanent magnet is of a truncated conical shape and coaxially fixed to said first shaft, a bevel circumference surface of the truncated conical shape of said permanent magnet is magnetized by magnetic poles alternating in a reverse polarity along a circumferential direction at regular intervals, said magnetic yokes are opposing said bevel circumference surface of said permanent magnet at a regular interval, said magnetic yokes and said flux condensing rings are of a truncated conical shape, and said flux condensing rings are disposed parallel to and equally spaced from said magnetic yokes respectively.