The basic components of a hydraulic door closer include a support guide, transmission gear, return spring, one-way valve, rack plunger, throttle valve core and housing, end cover, sealing ring, and connecting rod. The shell and connecting rod serve to fix the door closer and connect the door leaf and frame.
The working principle of the door closer is that when the door is opened, the door body drives the connecting rod to move and causes the transmission gear to rotate, driving the rack plunger to move to the right. During the process of the plunger moving to the right, the spring is compressed, and the hydraulic oil in the right chamber is also compressed. The check valve ball on the left side of the plunger opens under the action of oil pressure, and the hydraulic oil in the right chamber flows through the check valve to the left chamber. After the door opening process is completed, due to the compression of the spring during the opening process, the accumulated elastic potential energy is released, pushing the plunger to the left, driving the transmission gear and door closer connecting rod to rotate, causing the door to close.
During the spring release process, due to the compression of the hydraulic oil in the left chamber of the door closer, the one-way valve is closed, and the hydraulic oil can only flow out through the gap between the housing and the plunger, and returns to the right chamber through the small holes on the plunger and two flow channels equipped with throttle valve cores. Therefore, hydraulic oil creates resistance to the release of the spring, which achieves buffering effect through throttling, controlling the speed of door closure. The throttle valve on the valve body can be adjusted to control the variable closing speed of different stroke segments. Although there are differences in the structure and size of door closers produced by different manufacturers, the principle is the same.
The types of door closers can be divided into: external and embedded top door closers, embedded middle door closers, bottom door closers (floor springs), vertical door closers (built-in vertical door closers), and other types of door closers.