Abstract: A Stirling cycle type engine is disclosed in which a displacer piston and power piston operate within a cylinder due to flow of a working fluid which is heated and cooled by a heater element and a cooler element. The cylinder is divided into an upper expansion chamber and a lower compression chamber by a displacer piston. The lower chamber is defined between the displacer piston and power piston. The upper chamber and lower chamber are connected to one another through a serially interconnected heater, a regenerator and a cooler, whereby the working fluid flows into the lower chamber from the upper chamber or vice versa. The regenerator and the cooler are disposed on one outer peripheral side of the cylinder and vertically aligned therewith. Thus, the radial size of the engine is reduced without reducing its efficiency.

Abstract: A hot gas reciprocating apparatus is disclosed in which a displacer piston and power piston operate within a cylinder due to flow of medium gas which is heated and cooled through a heater and a cooler. The cylinder is divided into a upper chamber and lower chamber by the displacer piston, and the lower chamber is defined between displacer piston and power piston. The upper chamber and lower chamber are connected with one another through the heater, a regenerator and the cooler, whereby the medium gas flows into the lower chamber from the upper chamber or vice versa. The heater, which receives heat from heat sources, projects radially from the cylinder to extend over the heat source; and the cooler projects radially from the cylinder on an opposite side from which heater extends. The heater and cooler are axially spaced from one another along the axis of the cylinder.