Abstract: The invention can prevent gas leakage and reduce friction force while relaxing tolerance for manufacturing a displacer and the like for Stirling cycle machines. Gas leakage between the outer periphery of a seal (1) and the inner peripheral surface (5a) of a cylinder (5) is prevented. Accordingly, precise finish of the radial clearance between the displacer (2) and the cylinder (5) is not required. As the difference of pressures between the front and rear spaces of the displacer (2) is small, the gas leakage is sufficiently prevented without pressing the seal (1) against the inner peripheral surface (5a) of the cylinder (5). On the other hand, as the friction force generated between them is significantly small, it does not affect the reciprocation of the displacer. As the seal (1) is provided so as not to be restricted axially and radially, the displacer is kept closely contacted with the inner peripheral surface (5a) of the cylinder (5) even if the displacer (2) eccentrically shifts.

Abstract: The invention can prevent gas leakage and reduce friction force while relaxing tolerance for manufacturing a displacer and the like for Stirling cycle machines. Gas leakage between the outer periphery of a seal (1) and the inner peripheral surface (5a) of a cylinder (5) is prevented. Accordingly, precise finish of the radial clearance between the displacer (2) and the cylinder (5) is not required. As the difference of pressures between the front and rear spaces of the displacer (2) is small, the gas leakage is sufficiently prevented without pressing the seal (1) against the inner peripheral surface (5a) of the cylinder (5). On the other hand, as the friction force generated between them is significantly small, it does not affect the reciprocation of the displacer. As the seal (1) is provided so as not to be restricted axially and radially, the displacer is kept closely contacted with the inner peripheral surface (5a) of the cylinder (5) even if the displacer (2) eccentrically shifts.