Patent ID: 8615993

Claim:
A free-piston Stirling cycle machine having an improved bearing support system, the machine including a casing containing a cylindrical, free, power piston and a displacer piston, each piston having a clearance seal with a seal length and an axial center and reciprocatable in a cylinder mounted to the casing, wherein the improvement comprises: (a) at least a selected one of the pistons having a seal length in the range of 0.3 times the diameter of the piston to 1.5 times the diameter of the piston; (b) a non-compliant connecting rod fixed to an end of the selected piston; (c) the selected piston and connecting rod together being supported in the casing by two bearings which are (i) a gas bearing formed at the interface between the selected piston and its associated cylinder at the piston clearance seal; and (ii) a radially acting spring bearing fixed to the casing and extending to fixed connection to the connecting rod, the distance from the gas bearing to the connection of the radially acting spring bearing to the connecting rod being greater than the seal length of the piston.