IMPROVED MULTI-PIECE PISTON FOR A FREE PISTON MACHINE

摘要

The concentricity and coaxiality of a central bore through a piston for a free piston Stirling machine is improved with a piston that has a sleeve with a core constructed from at least two, separate, axially-engaging core components sealed within the sleeve. During fabrication, a central bore is machined through each of the core components. The piston is assembled by heating the sleeve and cooling the core components, inserting the core components into the sleeve and then allowing the sleeve to cool and the core components to warm. This drives the core components into sealed engagement with each other and with the sleeve and aligns the central bore coaxially with the outer cylindrical surface of the sleeve.