What is a door closer?

Door closer is a spring-like hydraulic device on the door head. When the door is opened, it can be released after compression and the door will close automatically. It has the function of spring door, which can ensure the door to close to the initial position accurately and timely after opening. Modern hydraulic door closers (door closers for short) began with a patent registered by Americans in the early 20th century. Different from the traditional door closer, it achieves the buffering effect by throttling the liquid in the door closer. The core of the design idea of hydraulic door closer is to control the door closing process, so that the functional indexes of the door closing process can be adjusted according to people's needs.

Functional importance

The significance of the door closer is not only to automatically close the door, but also to protect the door frame and door body (smooth door closing). More importantly, door closers have become an indispensable part of intelligent management of modern buildings.

Door closers are mainly used in commercial and public buildings, but also in families. They have many uses, the most important of which is to make doors close automatically to limit the spread of fire and ventilation in buildings.

principle of operation

door closer

The basic components of the hydraulic door closer are supporting guide rail, transmission gear, return spring, one-way valve, rack plunger, throttle core and shell, end cover, sealing ring and connecting rod. The shell and connecting rod play the role of fixing the door closer and connecting the door leaf with the door 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 the transmission gear rotates to drive the rack plunger to move to the right. When the plunger moves 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 into the left chamber through the check valve. When the door opening process is completed, the spring is compressed during the door opening process, and the accumulated elastic potential energy is released, which pushes the plunger to move to the left and drives the transmission gear and the connecting rod of the door closer to rotate, thus closing the door.

During the release of the spring, because the hydraulic oil in the left cavity of the door closer is compressed, the one-way valve is closed, and the hydraulic oil can only flow out through the gap between the shell and the plunger, and then flow back to the right cavity through the small hole on the plunger and two flow channels equipped with throttling cores. Therefore, the hydraulic oil constitutes resistance to the release of the spring, that is, the buffering effect is achieved by throttling, and the speed of closing the door is controlled. The throttle valve on the valve body can be adjusted to control the variable closing speed of different stroke sections. Although the structure and size of door closers produced by different manufacturers are different, the principle is the same.

The types of door closers can be divided into: external door closers and embedded door closers, embedded door closers, door bottom door closers ([1] floor springs), vertical door closers (built-in vertical door closers) and other types of door closers.