| 摘要 |
The object of the invention is, in a rotation sensor unit comprising a housing in which the outer race of a rolling bearing is fitted, a shaft supported by this rolling bearing, and a magnetic encoder for detecting the rotation of the shaft, to shield the magnetic sensor element from external magnetic field without depending on a dedicated magnetic shield cover or the housing, while preventing displacement of the magnetic sensor unit and the encoder relative to each other. A lid 2 is pressed against the housing 2 to push the outer race 11 of the rolling bearing 1, thereby applying a preload to the bearing 1 and increasing the rigidity of the bearing 1, so as to prevent run-out of the shaft 3. An encoder 42 is supported on this shaft 3, and a magnetic sensor element 41 is supported on the lid 6, which is pressed against the housing 2. Thus, it is possible to prevent displacement of the magnetic sensor element 41 and the encoder 42 relative to each other. The shaft 3, lid 6 and outer race 11, etc. are made of a soft magnetic material to define a magnetically shielded space between one axial end surface of the shaft 3 and the lid 6, with the magnetic sensor element 41 mounted in the magnetically shielded space.
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