Perhaps you have encountered such a situation in your life, which is also closed. Some doors suddenly close, and some close slowly. Why? Careful friends will find that the above are products with "door closer" installed that close slowly. This product is produced by this effect.
Why can the door closer make the door close slowly?
The answer is similar to the working principle of closing the door. The specific reason is that the closer the spring is in the release process, the hydraulic oil left by the closed door cavity is compressed. The check valve is closed, and the hydraulic oil flows out only through the gap between the housing and the plunger. The rear passage hole on the plunger and the two doors equipped with the return valve are close to the right cavity of the throttle valve core. Therefore, the hydraulic oil forms a certain resistance to the release of the spring, which acts as a buffer through the throttle, and the closing speed of the door is controlled.
In addition, the throttle valve on the valve body can be adjusted to control the stroke at different stages to control different closing speeds.
Summary: in the current factory door closers, although some door closers have different buffering effects, their structures and sizes have these differences, but the overall principle is the same.