Operation Principles and Characteristics of Door Closer

The door closer is a hydraulic spring-like device installed on the top of the door. It can compress and release when the door is opened, automatically closing the door and playing a role similar to a spring, ensuring that the door is accurately and timely closed to the initial position after it is opened. Modern hydraulic door closers (referred to as door closers) began with a patent registered by an American in the early 20th century. Unlike traditional door closers, it achieves buffering by throttling the liquid in the door closer. The core of the hydraulic door closer design concept is to control the closing process and adjust various functional indicators of the closing process according to human needs.

1. The Function of the Door Closer

The significance of the door closer is not only to automatically close the door, but also to protect the door frame and door body (smoothly closed). More importantly, the door closer has become an indispensable part of modern intelligent building management. Door closers are mainly used in commercial and public buildings, but they are also used in homes. They have many uses, the most important of which is to close the door by itself to restrict the spread of fire and ventilation in the building.

2. The Working Principles of the Door Closer

The basic components of the hydraulic door closer include supporting guiding parts, transmission gears, reset springs, check valves, rack plunger, throttle valve core and housing, end cover, sealing ring and connecting rod. The housing and connecting rod fix the door closer and connect the door leaf and door frame. The working principle of the door closer is: when the door is opened, the door body drives the connecting rod to move, and drives the transmission gear to rotate, driving the rack plunger to move to the right. During the process of plunger moving to the right, the spring is compressed and the hydraulic oil in the right cavity is also pressurized. The check valve ball on the left side of the plunger opens under the action of the oil pressure, and the hydraulic oil in the right cavity flows to the left cavity through the check valve. After the opening process is completed, the elastic potential energy accumulated by the spring during the opening process 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 cavity of the door closer, the check valve is closed. The hydraulic oil can only flow out through the gap between the housing and plunger and return to the right cavity through the small hole on the plunger and the two flow channels with throttling valve cores. Therefore, the hydraulic oil constitutes resistance to the spring release, achieving buffering by throttling and controlling the closing speed of the door. The throttle valve on the valve body can be adjusted to control the variable closing speed in different stroke segments. Although the structures and sizes of door closers produced by different manufacturers may vary, the principle is the same.

The types of standard door closers can be divided into: external and embedded door top door closers, embedded door middle door closers, floor door closers (ground springs), vertical door closers (built-in vertical door closers), and other types of door closers.

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