The invention relates to a reciprocating piston composed of ceramic material for a reciprocating-piston engine with crank drive, wherein the reciprocating piston is rigidly screwed to a piston rod by a screw, wherein between the reciprocating piston and the piston rod there is braced at least one disc composed of metallic material, wherein the screw is composed of a metallic material, wherein the coefficient of thermal expansion .sub.piston of the material of the reciprocating piston is lower than the coefficient of thermal expansion .sub.screw of the material of the screw, and the disc is an expansion compensation disc, wherein the coefficient of thermal expansion .sub.Disc 1;2 of the material of the expansion compensation disc is greater than the coefficient of thermal expansion .sub.screw of the material of the screw, and to a reciprocating-piston engine having a reciprocating piston of said type, and to a cylinder of a reciprocating-piston engine having a cylinder of said type.

A method for improving combustion in a combustion chamber of an internal combustion engine, a heat retaining element, and an internal combustion engine are provided. The internal combustion engine includes a main combustion chamber arranged between a head and a reciprocating piston, and a heat retaining element provided between the head and the main combustion chamber. The heat retaining element is a self-supporting structure coupled to the head that is configured to reduce heat transfer from the main combustion chamber into the engine head. The heat retaining element includes a head-facing portion substantially corresponding in shape to a portion of the head facing the main combustion chamber. The heat retaining element is provided such that a gap is provided between the head-facing portion of the heat retaining element and the portion of the head facing the main combustion chamber.

A compressor may include a first scroll, a second scroll and a modulation system. The first scroll may include a first endplate and a first spiral wrap. The second scroll may include a second endplate and a second spiral wrap interleaved with the first spiral wrap and cooperating to form a plurality of working fluid pockets therebetween. The modulation system may include a temperature-responsive displacement member that actuates in response to a temperature within a space rising above a predetermined threshold. Actuation of the displacement member may be controlled to control a capacity of the compressor.