Patent ID: 8844579
Filing Date: 2014-09-30
Classification: F01N,F16L

Abstract:
1. A flexible tube comprising: a cylindrical bellows tube; a cylindrical interlock tube placed inside the bellows tube; and upstream-side and downstream-side joint pipes respectively coupled to coupling end portions formed at opposite ends of the bellows tube, wherein the bellows tube includes a bellows portion in which ridge portions and valley portions are alternately formed in an axial direction of the bellows tube between the coupling end portions thereof, the upstream-side and the downstream-side joint pipes include respective extension portions each extending from a portion thereof coupled to the bellows tube towards a center of the bellows tube in the axial direction of the bellows tube, the extension portions being fitted and fixed to respective fixing end portions at opposite ends of the interlock tube, the interlock tube is formed such that the fixing end portions thereof are enlarged in diameter as compared with a middle portion of the interlock tube on an inner side in an axial direction of the interlock tube and a diameter of each of the fixing end portions thereof is larger than a diameter of the interlock tube at the middle portion, the extension portions of the upstream-side and the downstream-side joint pipes are fitted and fixed to inner peripheral surfaces of the respective fixing end portions, and depths of the valley portions of the bellows portion that are located over outer peripheral surfaces of the fixing end portions of the interlock tube are smaller than a depth of each of the valley portions of the bellows portion that are located closer to the center of the bellows portion in the axial direction than the valley portions over the fixing end portions.