Free-piston stirling engine inertial cancellation system

Abstract

A free piston Stirling engine inertial cancellation system includes a displacer reciprocating in a hermetic vessel enclosing a working space to circulate working gas through a heater, regenerator, and cooler to create a pressure wave in the working space. A power piston, mechanically unconnected to the displacer, is reciprocally driven by the pressure wave to produce a power output stroke in one direction and a working gas compression stroke in the other direction. The displacer and the power piston form substantially a first mass in the working space. A second mass, outside the working space and preferably including an alternator plunger, is mounted in the vessel and is coupled to the first mass momentum exchange relationship. Spring means and tuning means cause the second mass to reciprocate out-of-phase with the displacer and the power piston so that the phase of the moving masses produces inertia phasors which substantially cancel and so that little or no inertia of the reciprocating masses is transmitted through the vessel to the mounting structure of the engine.