PROBLEM TO BE SOLVED: To provide a duckbill valve capable of making a slit hardly opened and improving its air-tightness.SOLUTION: This invention relates to a duckbill valve 1 for use in restricting a flow of fluid from an extremity end side toward a base end direction comprising: a cylindrical main body part 11 a pair of slant parts 14 arranged at an inner peripheral surface spaced apart by a predetermined spacing from the extremity end of the main body part 11 and extending in slant manner from the base end side toward the extremity end direction to cause its extremity end to be converged a linear line slit 15 that can be opened or closed to form while extremity ends of both slant parts 14 are being contacted therewith protrusions 13 arranged at an outer peripheral surface of the main body part 11 and extending along an axis line of the main body part 11 and ribs 16 extending from a position at the inner peripheral surface of the main body part 11 where they oppose against the protrusions 13 up to the slant parts 14.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2018,JPO&INPIT【課題】スリットを開きにくくして気密性を向上させることができるダックビル弁を提供する。【解決手段】 先端側から基端方向への流体の流動を規制するダックビル弁1において、円筒形の本体部11と、該本体部11の先端から所定の間隔を存した内周面に設けられ、基端側から先端方向に向けて、先端が収束するように傾斜して延びる一対の傾斜部14と、両傾斜部14の先端が接すること形成される開閉可能な直線状のスリット15と、前記本体部11の外周面に設けられ、該本体部11の軸線に沿って延びる突起部13と、前記本体部11の内周面のうち該突起部13と対向する位置から前記傾斜部14まで延びるリブ16とを備える。【選択図】 図2
