Abstract: A heater head for a multi-cylinder double-acting hot gas engine of the type having an annular regenerator surrounding each cylinder is provided with tubes connecting each cylinder with its surrounding regenerator. All tubes have three tube parts of identical shape. A first tube part is of involute shape and a second and a third tube part are of different involute shape. Half of all tubes have their first tube part connected to the cylinders, while the other half of the tubes have their first tube part connected to the regenerator.

Abstract: A system for conversion of solar radiation into electric power comprises a single hot gas engine and two identical electric generators mounted at the two ends of the power output shaft of the hot gas engine.

Abstract: A heater head for a multi-cylinder solar powered hot gas engine has a number of heater tubes lined on a conical wall exposed to the radiation.The tubes follow involute curves in two parts. The first parts leave very small gaps between them. The second parts arranged at a larger diameter from the center of said wall follow another involute each tube now leaving such gap relative its neighbor that a returned tube part may be arranged between.

Abstract: A compact six-cylinder, double-acting hot gas engine having a single central combustion chamber with the cylinders arranged in two groups of three and clustered around the combustion chamber axis at equal angular intervals. The engine has two crank shafts, one per group of three cylinders, rotating in the same direction and synchronized. Each crank shaft has three cranks with adjacent cranks angularly displaced 60 degrees. Each of the cranks of one crank shaft is directed oppositely to a respective one of the cranks of the other crank shaft.

Abstract: An improved hot gas engine heater head where a thermocouple is coaxially positioned in an isolation tube having one closed end and the isolation tube is coaxially positioned in one of a plurality of heater tubes forming a part of a working gas path between two variable volume chambers and traversing a combustion gas flow path. The thermo-couple is in heat-transfer contact with the working gas and is physically isolated from the working and combustion gases. The temperature signal from the thermo-couple is conducted by a conduction wire passing through heat insulating material such that neither the thermo-couple nor the conduction wire is exposed directly to the working gas or the combustion gas.

Abstract: Hot gas engine units of the type having four parallel cylinders arranged in two parallel rows of two cylinders per row may be effectively balanced by a minimum of counterweight masses. The engine pistons are connected to two parallel crank shafts and four primary counterweights are positioned on the crankshafts each diametrically opposite a respective crank. The crankshafts engage a common gear wheel rotating opposite to but at the same angular speed as the two crank shafts, and the gear wheel is mounted on a third shaft parallel to the two crank shafts. Secondary counterweights including at least two axially spaced, oppositely directed secondary counterweights positioned on the third shaft are used to cancel the moment about the engine vertical axis produced by the primary counterweights.

Abstract: Hot gas engine units of the type having parallel cylinders in two parallel rows and containing pistons connected to two parallel crank shafts engaging a common third output shaft are juxtaposed into an assemblage of four such units. The output shaft is common to all four units and each of four crank shafts is connected to pistons in cylinders of adjacent rows of neighboring units. In such assemblage the total number of crank shafts in four units is reduced from eight to four and one output shaft will replace four output shafts.