| 摘要 |
PROBLEM TO BE SOLVED: To fit a frame directly to a drive coil and to improve heat radiation effect by forming the frame of a heat-conductive metal material and fixing a coil to the frame across a heat-conductive member. SOLUTION: A frame 3 is made of a metallic material with superior heat conductivity and has a hollow cylindrical pole part 3a standing from the bottom surface around a center axis X along the center axis. A heat sink 10 is a heat radiator composed of heat radiating fins, etc., made of heat-conductive members, and fitted to the pole part 3a and fixed to the frame 3 to conduct the heat from the pole part 3 and radiate it to the outside space. A drive coil 9 is a cylindrical coil, which is formed by winding an electric wire having an insulating coating in the same direction more than once, has the internal diameter nearly equal to the external diameter of the pole part 3a and is inserted into the pole part 3a to have its bottom surface and inner peripheral surface in contact with the pole part 3a, so that the coil is fixed to the frame 3.
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