Heat engine

A heat engine comprising:

• a high-temperature space portion and a low-temperature space portion, each of which has a working gas with a different temperature range from each other;
• a regenerator provided between the high-temperature space portion and the low-temperature space portion;
• a first piston including a cylinder portion integrally formed inside the first piston, the first piston configured to cause volumetric changes of the working gases in each of the high-temperature space portion and the low-temperature space portion and transmit motive energy on receipt of pressure changes of the working gases;
• and
• a second piston and a third piston provided in the low-temperature space portion and the high-temperature space portion, respectively, the second piston and the third piston configured to transfer the working gases between the high-temperature space portion and the low-temperature space portion and move with a 180° phase difference from each other with respect to the regenerator,
• wherein the second piston is slidably housed in the cylinder portion of the first piston,
• the first piston, and the second piston and the third piston are configured to move with a phase difference smaller than 180°,
• heat and motive energy are exchanged by using the volumetric changes in the high-temperature space portion and the low-temperature space portion located respectively on both sides of the regenerator, as well as by using the transfer of the working gases, and
• the second piston and the third piston are connected to each other with a connecting rod.