Abstract: An improved door closer includes a base fixedly provided on an inner side of a door, and a link member. The inner side of the base is provided with a piston. The piston is biased by a release member, and has a connecting block and left and right end blocks extending upward from two ends of the connecting block. The bottom portion of the connecting block is provided with a guide groove in the same direction as a long axis of the base. The right end block is recessed inward to form an insert groove. A roller is pivoted in the insert groove. A transmission shaft passes through the guide groove of the piston. The intermediate portion of the transmission shaft is provided with a cam abutting against the roller. When an external force pushes open the door, the cam is rotated to cause the piston to bring the release member into a compressed state.

Abstract: A locating structure of an oil pressure door closer is composed of a locating plate, a main body of the door closer, and a plurality of fastening pins. The locating plate is fastened with a door and provided with a plurality of fastening holes. The main body is provided in one longitudinal side thereof with two longitudinal edges parallel to each other and forming therebetween a longitudinal space for accommodating the locating plate. The two longitudinal edges are provided with a plurality of through holes corresponding in location to the fastening holes of the locating plate. The fastening pins are received in the through holes and the fastening holes for fastening the main body with the locating plate.