Do you know how door closers work?

The basic components of a hydraulic door closer include support guide components, transmission gears, reset springs, one-way valves, rack plungers, throttle valve cores and shells, end caps, sealing rings, and connecting rods. 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 right movement of the plunger, the spring is compressed, and the hydraulic oil in the right chamber is also compressed. The one-way 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 into the left chamber through the one-way valve. 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, and closing the door.

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 return to the right chamber through the small hole on the plunger and two flow channels equipped with throttle valve cores. Therefore, hydraulic oil creates resistance to the release of the spring, achieving a buffering effect through throttling, and 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 the structure and size of door closers produced by different manufacturers may vary, the principle is the same.