| 摘要 |
PURPOSE:To make a frame-shaped yoke lightweighted without damaging heat dissipation by forming the frame-shaped yoke using a composite body made of a high permeability material layer overlapped on a good thermal conductivity frame body made of aluminum or its alloy. CONSTITUTION:A frame-shaped yoke 16 is comprised with a good thermal conductivity frame body 19 made of aluminum or its alloy and a high permeability material layer 20 overlapped on this frame body 19. Amorphous metal can be used as the material of the high permeability material layer 20. The cross section of the high permeability material layer 20 made of the amorphous metal with the permeability of approximately 20,000 can be only approximately one hundredth, as compared with the cross section of the frame-shaped yoke made of iron. On the other hand, since the good thermal conductivity frame body 19 that supports and reinforces the high permeability material layer 20 is exceedingly lightweighted and is actuated as a good heat dissipation blade for permanent magnets 15 and 17, these permanent magnets can be prevented from occurrence of high temperature demagnetization. In addition, a heat dissipation plate 13 can be made compact. |
