| 摘要 |
A manhole cover device is provided to have the functions of drainage and counter current simultaneously with one group of flaps only, to have excellent functions of drainage and counter current with low expenses and to make drainage capacity and counter current capacity equal to each other, and to prevent the generation of an offensive odor and the inhabitation of harmful insects. A manhole cover device(101) comprises a case body(120) provided with a hanging projection to hang on an upper end projection of a manhole, an opening formed on the bottom of the case body, and an opening and closing device(45) opening and closing the opening. The opening and closing device comprises a flap(88) composed of a first plate(88a) and a second plate(88b) connected at two sides to rotate on a rotary shaft fixed to the case body and formed to have the load difference, and many flap stoppers(90) limiting the revolving angle of the flap. |
