Patent ID: 8733096

Claim:
Heat engine comprising: at least two cylinder-piston units, each containing an expansion fluid, which acts on a first side of the piston and which expansion fluid changes its volume in the case of a change of temperature and thus moves the piston, heat supply elements for the individually controllable supply of heat to the expansion fluid of each cylinder-piston unit, a control means configured to control the heat supply elements to allow each expansion fluid to alternately heat up and cool down and thus move the pistons, a prestressing fluid circulating in a hydraulic circuit, the circuit including a common header connected for communication of the prestressing fluid to each of the cylinder-piston units for direct contact with a second side of the piston of each cylinder-piston unit in order to exert a common prestressing pressure on the expansion fluid in each cylinder-piston unit whereby when the control means controls one of the heat supply elements to heat the expansion fluid for expansion, the corresponding piston is moved by the expansion of the expansion fluid such that the prestressing fluid contacting the second side of the corresponding piston is exhausted from the corresponding cylinder-piston unit into the common header causing a corresponding increase in the prestressing pressure within each of the other cylinder-piston units to maintain the common prestressing pressure as equal on all pistons of the cylinder-piston units; a pressure gauge in communication with the prestressing fluid to measure the common prestressing pressure; the control means being in communication with the pressure gauge, and the control means controlling a heating and cooling phase of the heat supply elements in dependence on the measured common prestressing pressure in order to maintain the prestressing pressure within a predetermined range.