JPS632033B

PURPOSE:To enable to obtain a higher thermal efficiency on an engine by a method wherein a shape memory belt engaged with the first and the second belt grooves, with at least a part thereof crossed, is heated and cooled. CONSTITUTION:The shape memory belt 20 is engaged with pulleys 16, 17, 18, 19, with a belt part between the pulleys 16 and 17 and a belt part between the pulleys 18 and 19 constituting a two-level crossing. The part of the belt 20 between the pulley 16 and the pulley 19 is heated by immersing it in a warm liquid 23, while the part of the belt 20 between the pulley 18 and the pulley 17 is cooled by immersing it in a cool liquid 24. In this case, heating means to bring the belt 20 to a temperature of not lower than the transformation temperature thereof, and cooling means to bring the belt to a temperature of not higher than the transformation temperature. When the belt 20 is heated, it tends to recover the prememorized shape, inducing a tension at and around the heated part thereof. Accordingly, the tension generated in the belt 20 causes the engine to rotate at a favorable thermal efficiency.