Abstract: A thermally insulating lining for the housing of the heater system ensures that on the outside of the heater system only low temperatures are reached which are not dangerous to operators in the vicinity of the engine. Combustion air duct means between an air preheater and a burner is formed by a large number of tubes arranged alongside each other in at least one row and along an inside wall of the combustion chamber. These tubes ensure that the flow state remains satisfactory and constant and they are substantially more durable than sheet metal duct means as used hitherto.

Abstract: A thermally insulating lining for the housing of a heater system for a Stirling, or hot air engine ensures that only safe temperature will be reached on the outside of the heater system. The insulating lining is arranged in two parts. An insulating wall is made up of individually adjacentely placed, replaceable insulating elements in the form of ceramic tiles, and/or ceramic tubes, and an intermediate space between the tiles and the outer wall. The intermediate space is separated, if desired, from the insulating elements by a ceramic paper. The intermediate space is packed with ceramic fiber batts, or loose, lump ceramic insulating material.

Abstract: The invention provides a method for the production by welding of a heat exchanger pipe starting with a round metallic pipe onto which external metallic fins are secured so as to be perpendicular to the axis of the pipe. Each metallic fin is produced in two halves in such a manner each fin has a coxial semicircular recess or bay whose radius mateches the external diameter of the metallic pipe and on each side of such recess there are two side surfaces so that after mounting the fin halves on the pipe there is a small gap at the parting line between the two halves. After mounting the two fin halves on the metallic pipe the respectively radially outer and parts of the gap are spot welded together and on cooling down the fin the fins shrinkage at the weld spots causes the two fin halves to pressed on the pipe with their recess boundaries engaging the outer surface of the pipe.

Abstract: The aim of the invention is to improve upon conventional electricity generator sets consisting of a driven generator with relatively complex couplings and possibly a gear box transmission between the crank shaft and the generator.In accordance with the invention the engine is a stirling or hot gas engine with at least four double acting cylinders, each of whose pistons placed between a hot and a cold cycle space is connected with a piston rod on a cross head linearly guided in a cross head guide and coupled via coupling member, more especially one in the form of a connecting rod, with a crank shaft. Furthermore the moving elements--permanent magnets or exciting windings--of a linear generator are located in each cross head and the stationary parts--stators--are arranged on the associated cross head guide. The crank shaft and linking members only serve to synchronize the working cycles of the engine and are therefore only designed for light duty.