Most of the known door closers are of the type which uses a spring housed in a casing having oil enclosed therein, the force of said spring urging the door in the closing direction.
In such conventional door closers, generally the casing or main body and the door are connected together by a double link and the force of the spring is transmitted to the door.
In the door closer of the aforesaid construction, since the casing or main body is required to be of sealed construction, it must be constructed to prevent oil leakage. Another problem is that the assembly operation of the door closer takes time and is expensive. For the sake of convenience of construction of the main body of the door closer, the double link is invariably positioned outside the main body, offering a problem that it detracts from the external appearance.