Fabrication and Output Power Characteristics of a Pulley-type SMA Heat-engine Including the Idler Wheel with a Cooling System

抄録

A heat-engine using Ti-Ni shape memory alloy (SMA) has been investigated as a system for waste heat recovery potential. We had proposed a new SMA heat-engine with a forced cooling system in the pulley because of the cooling efficiency improvement of the SMA element. In this study, for the purpose of the further improvement of the pulley-type SMA heat-engine with a forced cooling system, we fabricated the new cooling mechanism with the idler wheel, and effects of cooling position on the output power characteristics of this engine are investigated. As a result of experiment, irrespective of cooling position, the output power increases with increase of the tensioning displacement provided by idler wheel. This tendency is because the applied strain of SMA element increases as the increase of tensioning displacement. Moreover, the installation of idler wheel leads to the unsymmetrical heating of SMA element, and then the bias torque is generated. When the idler wheel is installed at the position before the SMA element contacts with a bottom pulley, the bias torque with same rotative direction of heat-engine is generated. Therefore, the most desirable installation position of the idler wheel is the position before the SMA element contacts with a bottom pulley.