Patent ID: 7600464
Filing Date: 2009-10-13
Classification: F02G

Abstract:
1. An improved multi-piece piston for a free piston machine, the piston having an inner core axially within and sealingly engaging an outer sleeve, the core having a cavity formed on its exterior surface forming a gas bearing plenum, the piston having a network of gas bearing passages in fluid communication with the plenum and extending through the piston to form a gas bearing lubrication system, wherein the improvement comprises the core having: a first core component and a second core component that axially engage each other at interfacing ends, each core component having a coaxial, central bore extending along its entire length, the first core component being sealingly engaged to the second core component and having a coaxially-protruding neck that has an end that sealingly engages the second core component, the neck having a tapered exterior surface that matingly engages a tapered, coaxial shoulder in the second core component for creating the sealing engagement between the core components.