| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas spring preventing breakage of an oil film even when there is excitation by minute amplitude, preventing wear of a main lip and a sub lip, and capable of improving durability of a seal. SOLUTION: In the gas spring, a piston rod 3 is movably inserted inside a cylinder 1 via a piston 2, the piston rod 3 is constantly energized in an extending direction by gas pressure, the seal 19 is provided near an end part of the cylinder 1, the seal 19 comprises a seal body 20, an outer circumferential lip 21, and the main lip 22 provided in an inner end side of the seal body 20, the main lip 22 is brought into sliding contact with an outer circumference of the piston rod 3, and the outer circumferential lip 21 is abutted on an inner circumference of the cylinder 1. It is characterized by that insert metal 24 is embedded in the seal body 20, the sub lip 23 facing the main lip 22 is provided in an outer end side of the seal body 20, an oil sump chamber 26 is partitioned between the main lip 22 and the sub lip 23, and an inner diameter of an inner circumferential face in a tip of the sub lip 23 is provided smaller than an outer diameter of the piston rod 3 to set an approach angle in a free state of the inner circumferential face to the piston rod 3 at a minus.
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