Patent ID: 7775041

Claim:
A Stirling engine comprising: a piston reciprocating in a cylinder; and a displacer reciprocating with a predetermined phase difference kept relative to the piston, wherein a working gas is moved between a compression space formed at one end of the displacer and an expansion space formed at another end of the displacer, and wherein, for a purpose of keeping a proper pressure balance between a back pressure space formed outside an outer circumferential face of the cylinder and the compression space, a first flow passage is formed in the piston to run from a compression-space side end face thereof to an outer circumferential face thereof, and a second flow passage is formed in the cylinder so as to allow the first flow passage to communicate with the back pressure space when the piston comes into a predetermined position, wherein the second flow passage is composed of a through hole penetrating a wall of the cylinder in a radial direction and a communication passage formed between an inner yoke fitted on the outer circumferential face of the cylinder and the outer circumferential face of the cylinder.