The multi-temperature double-acting piston includes a peripheral sealing ring, a lower hot crown and/or an upper hot crown, and moves in translation in a cold cylinder of a heat engine which includes a lower cylinder head and an upper cylinder head, the piston including a central piston pin the lower piston rod of which passes through the lower cylinder head so as to be connected to a power transmission housed in a transmission casing, and the upper piston rod of which passes through the upper cylinder head so as to open out into a piston cooling and lubricating chamber, a lubricating-cooling gallery provided in the pin putting the chamber in communication with the casing via an internal piston volume.

Disclosed is an energy collector system applicable to internal combustion engines. It may include: a) a collector of thermal energy from the exhaust gases; b) a thermal tank covered by helical tubes to gain heat by the exhaust gases; c) a heat exchanger; and d) an outer element capable of converting thermal energy into mechanical energy, such as a closed Brayton cycle turbine, a Stirling engine, a Rankine turbine or an open loop air motor for converting mechanical energy (coupling the difference in rpm) into electrical energy with an electrical generator. The thermal energy collector may be composed of a heat exchanger that collects energy from the exhaust gases. The electrical energy generated may be used for driving a hybrid vehicle. The thermal tank is capable of storing energy as heat, as well.