To provide a novel
cam action hydraulic door closer particularly, in a technical field of a door closer.SOLUTION: Omitting a gear and a rack structure greatly simplifies the structure and volume of a door closer. A bidirectional
piston always abuts in an elastic manner on an outer circumferential surface of a transmission
camshaft through a driving spring. When the transmission
camshaft operates, the bidirectional
piston moves in conjunction therewith, the driving spring is compressed, and the driving spring stores force. At the same time, an overload valve realizes a circulation of hydraulic oil between a spindle chamber and a spring chamber. Therefore, when the transmission
camshaft rotates in a door closer housing, the bidirectional
piston is subjected to damping effect on the transmission camshaft and the damping effect of hydraulic oil. This reduces the
instantaneous speed when the door is closed, and a new
cam action hydraulic door closer provides a sufficient
cushioning effect when the door is closed. In this way, the new
cam action hydraulic door closer of the present invention has the advantages including simple structure, easy
assembly, high production efficiency, low
failure rate, and stable performance.SELECTED DRAWING: Figure 1