PURPOSE: To improve the durability of the root parts of a bellows by providing an inner cylinder, for preventing the pleats of the bellows from mutual contact, inside the bellows with its crest curvature radius smaller than its root curvature radius, and providing a self-sealing mechanism for sealing liquid between the inner cylinder and the bellows inner face.
CONSTITUTION: One end of a metal bellows 35 with its crest curvature radius smaller than its root curvature radius is airtightly fixed to an end member 23, and a free end 35b is closed with a cap 36. An inner cylinder 31 with one end 31a thereof integrated with the end member 23 is disposed inside such a bellows 35. A seat 33 with a flow hole 32 is further provided at the end part 31b of the inner cylinder 31, and a seal member 70 is rigidly fixed on the inner face side of the cap 36 opposed to the seat 33, so that the pleats of the metal bellows 35 are prevented from mutual contact, and also liquid is sealed between the bellows 35 and the inner cylinder 31 by a specified quantity of contraction to prevent crushing. The durability of the root parts is therefore secured to improve the durability of the metal bellows 35.
SATO TOSHIAKI
TAJIMA HAJIME
