John F Corey

US Patent:

6564552, May 20, 2003

Filed:

Apr 27, 2001

Appl. No.:

09/844177

Inventors:

William C. Ward - Santa Fe NM
John A. Corey - Melrose NY
Gregory W. Swift - Santa Fe NM

Assignee:

The Regents of the University of California - Los Alamos NM

International Classification:

F02G 106

US Classification:

60520, 123 46 R

Abstract:

A free-piston device has a stabilized piston drift. A piston having a frequency of reciprocation over a stroke length and with first and second sides facing first and second variable volumes, respectively, for containing a working fluid defining an acoustic wavelength at the frequency of reciprocation. A bypass tube waveguide connects the first and second variable volumes at all times during reciprocation of the piston. The waveguide has a relatively low impedance for steady flow and a relatively high impedance for oscillating flow at the frequency of reciprocation of the piston, so that steady flow returns fluid leakage from about the piston between the first and second volumes while oscillating flow is not diverted through the waveguide. Thus, net leakage about the piston is returned during each stroke of the piston while oscillating leakage is not allowed and pressure buildup on either the first or second side of the piston is avoided to provide a stable piston location.