| 摘要 |
<p>A rotational speed can be reliably detected at low cost by stabilizing the density of a magnetic flux coming from a permanent magnet encoder (10b) and reaching the detection portion of a sensor. The residual magnetic flux densities of an inner race (1), an outer race (14) and a ball (5) each made of a magnetic material are individually 0.2 mT or less, and 2 mT or less when assembled into a roller bearing unit. Therefore, the magnetic flux coming from the encoder (10b) is hardly affected by the residual magnetic flux of the roller bearing unit.</p> |
