| 摘要 |
PURPOSE: To materialize downsizing and minimize the cost increase by specifying the axial length of a magnet to a specified number of times of axial length of an armature iron core. CONSTITUTION: The axial length Lm of the magnet 3 mounted on a yoke 2 is made 75-85% the length Lc of an armature iron core 8. In the case of adopting an earth magnet, the volume, that is, Lm of the magnet shall be minimized to reduce material expense. At Lm/Lc=1, if the volume of the armature iron core is made fixed (Lc is fixed) from the condition where both volume ratio and torque ratio are 1.0, and Lm is made 0.8 times, torque decreases. To raise torque ratio to 1.0 with Lm/Lc=0.8 intact, there is necessity to put the volume ratio of the armature iron core to 1.1 times (Lc to 1.1 times). Accordingly, Lm becomes 0.8×1.1=0.88 times. Likewise, in the case that Lm/Lc=0.6, Lc is made 1.3 times, and Lm 0.78 times, and in the case that Lm/Lc=0.4, Lc is made 1.7 times, and Lm 0.68 times.
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