| 摘要 |
PROBLEM TO BE SOLVED: To provide a bearing device for a wheel having rotational frequency detection function and no risk of disconnection outside a car, and realizing further miniaturization, avoidance of complication of wiring, and improvement of sealability of the bearing. SOLUTION: Double row rolling elements 3 are interposed between an outward member 1 and an inward member 2. A generator 4 for generating electricity by relative rotation between the outward member 1 and the inward member 2 is provided. The generator 4 comprises a coil/magnetic material pair 17 formed by storing a coil in a ring member and a multipolar magnet 18. A transmission means 5 for transmitting wirelessly a signal of the rotational frequency of the wheel 13 outputted from the generator 4 is provided. The transmission means 5 may have a circular transmitter.
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