The purpose of this research is to clarify the requirements for the high output power density of SMA engine. In order to put the SMA engine in practical use, maximizing the output power density is most important from the viewpoint of economical efficiency. The output power of the SMA engine highly depends on the diameter of the SMA belt and the radius of the high temperature wheel. In this study we will change the diameter of the SMA belt and theoretically explain whether there is a relational expression between it and the radiuses of the high temperature wheel and the low temperature wheel of the SMA engine. If the radius of the low temperature wheel (R) is determined, the equipment width (W) of the SMA engine is also determined (W=2R). Next, the height of the SMA engine is determined experimentally by the cooling conditions of the SMA belt. Finally, the depth of the SMA engine is determined by the diameter of the SMA belt(D=d).Since the output power of the SMA engine can be calculated by the theoretical formula, we can divide it by the volume of the SMA engine and thus, calculate the output power density of the SMA engine. As the result, changing the diameter of the SMA belt, we can calculate the most appropriate value, at which the output power density of the SMA engine is maximal.

The purpose of this research is to cEarify the rcquirelrtents for thc high output pDwer SMA engine ． Thc maln 工 齟 esults obtained by th 量 s researcll are as follows ． In or 〔 】 er to ill じ rease the ｛ )utput power of the SMAengine 、 it is Decessary to make the radius 〔 ♪ f the high temperature whee ］as small as possible ， i・ vhile the mhlimum value (， f this radius is res し ricted by 亡 he distortion of the SMA belt、