Patent ID: 7198202

Claim:
A differential expansion absorption mechanism having a cylinder accommodated slidably inside a casing, a piston for partitioning the interior of the cylinder into two chambers, and a viscous fluid charged into the two chambers respectively, the differential expansion absorption mechanism serving to move the piston through the viscous fluid by causing the cylinder to slide, wherein an air chamber is connected via a throttle portion to at least one of the two chambers which rises in internal pressure when the cylinder or the piston is caused to slide, a flow resistance of the throttle portion being set such that at a predetermined pressure increase speed or higher, which predetermined pressure increase speed is generated in the chamber when the cylinder or the piston is caused to slide, the viscous fluid does not pass through the throttle portion, and at a lower pressure increase speed than the predetermined pressure increase speed, which lower pressure increase speed is generated in the chamber when the viscous fluid thermally expands, the expanded viscous fluid passes through the throttle portion.