Patent ID: 6848478

Claim:
A flexible tube comprising: a bellows tube comprising: a bellows portion formed of a plurality of first small-diameter parts of a first inner diameter; and straight portions formed at a first and a second end of the bellows tube, respectively; an interlock pipe in which a plurality of annular plate members or spirally wound band plates are flexibly coupled at side edges thereof to one another through an interlock mechanism, wherein the interlock pipe is disposed inside the bellows tube, and wherein the bellows tube and the interlock pipe have a common axis; and a restriction member disposed on the bellows portion, for serving as a fulcrum to restrict a vibration amplitude of the interlock pipe when the interlock pipe is vibrated, wherein an inner diameter of the straight portions of the bellows tube is smaller than the first inner diameter of the first small-diameter parts of the bellows portion, wherein inner peripheral surfaces of the straight portions are fixed to an outer surface of the interlock pipe, wherein the bellows portion comprises a second small-diameter part having a second inner diameter which is smaller than that of the first inner diameter of the first small-diameter parts; and wherein the restriction member is a buffer member disposed between an inner peripheral tip of the second small-diameter part and the outer peripheral surface of the interlock pipe.