| 摘要 |
PROBLEM TO BE SOLVED: To reduce a size and a weight and to improve reliability by holding a rolling unit rotatably provided between a stationary side track and a rotary side track by a synthetic resin retainer, and constituting pitch circle diameters of the unit and a part to be detected substantially the same. SOLUTION: An inner race 3 is rotatably supported at a bore side of an outer race 1 via a plurality of balls 5 rotatably held by a retainer 27 made of a synthetic resin between an outer race track 2 of an inner periphery of the race 1 and an inner race track 4 of an outer periphery of the race 3. Many slit-like through holes 15 are formed at a circular ring 14 of an encoder 7 externally fixed to the race 3. A forming part of the holes 5 and a pole part 16 of a solid portion between the adjacent holes becomes a part to be detected. Pitch circle diameters of the part to be detected and the balls 5 are substantially the same. A sensor 14 is embedded to be supported in a retaining ring 18 of a sensor housing 8a of the race 1. With this arrangement, a magnetic flux amount flowing in the sensor 24 as the encoder 7 rotates is changed, and a rotational speed of the race 3 can be known from a frequency of an output signal changing according to the change of the magnetic flux amount.
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