US Patent 7698989 Reciprocating piston machine

A reciprocating piston machine, in particular a compressor, such as for the air conditioning system of an automotive vehicle. The machine includes a casing and at least one casing cover. A working unit including pistons and is arranged or formed in the casing. The intake and exhaust zone or a front shaft bearing are arranged or formed in the casing cover (covers). The casing cover is screwed on the casing. The screw assembling is carried out with the aid of ring nuts or saw tooth screw threads between the casing and the casing cover, wherein the casing and cover are made of materials with different strengths and different thermal expansion coefficients.