US 7,600,464 B2
Multi-piece piston for a free piston machine
E. Todd Cale, Coolville, Ohio (US); Aaron M. Courtney, Athens, Ohio (US); and Jerry A Royse, Albany, Ohio (US)
Assigned to Sunpower, Inc., Athens, Ohio (US)
Filed on Apr. 12, 2007, as Appl. No. 11/734,377.
Prior Publication US 2008/0250784 A1, Oct. 16, 2008
Int. Cl. F01B 31/10 (2006.01); F02G 1/00 (2006.01)
U.S. Cl. 92—110  [92/153; 60/520] 11 Claims
OG exemplary drawing
 
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.