| 摘要 |
PROBLEM TO BE SOLVED: To provide a hub dynamo for a bicycle, whose hub is made of steel to suppress the occurrence of leakage flux and the decrease of generated voltage so that costs can be cut down and the hub dynamo can be miniaturized. SOLUTION: Spokes 1, 2 are coupled to collars 3 and a hub drum 4. A right bearing 6 is pressed and fitted in a center recession of the collar 3, and is held by a hub shaft 11 of a nonmagnetic material, to which a bearing sleeve 10 of a nonmagnetic material is fixed, in a sandwiched manner, then is coupled to a fork 25 of a front wheel. A left bearing 6 is pressed and fitted in a center recession of a circular cap 23 made of a steel plate, where the left bearing 6 is fixed and in contact with a bearing sleeve 20 of a nonmagnetic material. A coil 17 wounded on a coil bobbin and stator cores, 13, 14, and 15 are fixed to the hub shaft 11 of a nonmagnetic material to constitute the stator of the hub dynamo. The rotor of the hub dynamo is arranged on the side of the hub drum 4 and the cap 23. Magnets 7 are fixed to the inner surface of the hub drum 4, wherein the steel hub drum 4 also constitutes a yoke comprising a magnetic circuit formed by the magnets.
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