Stirling Machine

A Stirling machine comprising a displacer piston (6, 6a) and a moving member (14) of a generator or of an electric motor, the displacer piston (6, 6a) being mounted in a cylinder (2), in which it periodically displaces a working gas between an expansion chamber (VE) and a compression chamber (VC) which constitute the working volume of said Stirling machine, respectively associated with two working faces of said displacer piston (6, 6a) and causing said gas to pass through a hot side heat exchanger (7), linked to a heat source, a regenerator (9) and a cooling exchanger (8) linked to a heat sink and elastic return means exerting a force on this displacer piston (6, 6a), the cross-sectional area ratio (aC/aE) between the two working faces of said piston (6, 6a) being ≧0.35 so that its displacement along an axis X oriented toward the expansion volume VE generates an in-phase pressure component Px of said working gas opposing said displacement of said piston (6, 6a), so as to transmit all of said mechanical energy produced between this displacer piston (6, 6a) and said moving member (14), characterized in that the ratio of cross-sectional area aC/aE is less than 0.70 and in that it includes at least one resonant piston (10), coupled to said displacer piston (6, 6a) by a quantity of energy proportional to said pressure component Px.