| 摘要 |
PURPOSE:To prevent the generation of any fluctuating stress in the rotating blade and shaft of a cooling fan and any fluctuating load from being applied to the bearing of the fan as well as the generation of any eddy current electromotive force due to rotation of the blade, by making the axis of rotation of the blade coincident with the axis of magnetic flux of an electromagnetic induction apparatus. CONSTITUTION:A rotating blade 22 is disposed so that the rotation axis X-X thereof is coincident with the magnetic flux axis Y-Y of a reactor winding 21. If the rotating blade 22 rotates from a point A to a point A', for example, the magnetic flux density on the surface thereof is steady at B21. Therefore, attraction forces F21 and F21 acting on the blade 22 at the point A and the point A', respectively, are the same value as represented by the formula I . Accordingly, the blade 22 has no variations in attraction force due to rotation. In consequence, no repeated fluctuating stress is generated in the blade and also the rotating shaft. In addition, no fluctuating load is applied to a bearing 24. Accordingly, it is possible to completely avoid any fatigue failure and any reduction in life of the bearing. |
