(EP402516-B1)      heat engine (H) having a heat input from an external heat input means (10), a first working fluid operating in a closed cycle, and a work output means (20) to the surroundings, said first working fluid being cyclically compressed and expanded in a first subsystem (12-15) forming a property modulator (1), thereby cyclically changing at least one of its properties, i.e. pressure, temperature and volume, said property modulator (1) being connected to a second subsystem (22,23,24) forming an energy converter (2) wherein said change of said at least one property of the first working fluid of the property modulator (1) induces a corresponding change in a property of a working substance (22,23) of said energy converter (2), said property modulator further being provided with: a) an internal work transfer means (3,4;12-16) acting as a work transfer input means to compress said first working fluid during the first portion of a cycle and as a work transfer output means as the first working fluid expands during the second portion of the cycle, the sum of the mechanical work transfer input and output being to zero over the cycle, neglecting friction losses, b) the external heat input means (10), c) heat transfer means transferring heat from said property modulator (1) to said energy converter (2) during the first portion of the cycle and from said energy converter (2) to said property modulator (1) during the second portion of the cycle, thereby inducting the change in the property of the working substance of said energy converter, said energy converter (2) including means (22-29) for converting said change in property of said working substance of the energy converter (2) to work delivered to said work output means (20).    .D    (US5598704-A)      A heat engine having a heat input from an external heat input means, a first working fluid operating in a closed cycle, and a work output means to the surroundings,    said first working fluid being cyclically compressed and expanded in a first subsystem forming a property modulator, thereby cyclically changing at least one of its properties, i.e., pressure, temperature and volume,    said property modulator being connected to a second subsystem forming an energy converter wherein said change of said at least one property of the first working fluid of the property modulator induces a corresponding change in a property of a working substance of said energy converter, said property modulator further being provided with:    (a) an internal work transfer means acting as a work transfer input means to compress said first working fluid during the first portion of a cycle and as a work transfer output means as the first working fluid expands during the second portion of the cycle, the sum of the mechanical work transfer input and output being to zero over the cycle, neglecting friction losses;    (b) the external heat input means; and    (c) heat transfer means transferring heat from said property modulator to said energy converter during the first portion of the cycle and from said energy converter to said property modulator during the second portion of the cycle, thereby inducing the change in the property of the working substance of said energy converter to said property modulator during the second portion of the cycle, thereby inducing the change in the property of the working substance of said energy converter, said energy converter including means for converting said change in property of said working substance of the energy converter to work delivered to said work output means.