| 摘要 |
PURPOSE:To improve durability of a spring by forming the spring with shape memory alloy, thereby to change the inside diameter of the spring depending upon the temperature not to be out of contact with a shaft. CONSTITUTION:A spring 12 is formed of shape memory alloy to memory the shape of Fig. (I) at time of a low temperature and the shape of Fig. (II) at time of a high temperature. In either case of a low and high temperature, the size if the spring is not changed on the side where a driving shaft 5 is inserted. The diameter of the spring on the side where a driven shaft 6 is inserted is made larger than the outside diameter of the driven shaft 6 in case of a high temperature. Aa a result, in rotation A for power transmission, the spring 12 is adapted to fasten both shafts, but in the opposite rotation B of the driving shaft 5, slippage is caused between the power receiving surface 4 of the driven shaft 6 and the inside periphery of the spring 12, which causes the temperature to rise abruptly so as to increase the diameter of the spring on the side where the driven shaft 6 is inserted,resulting in stopping power transmission. |
