The method and working principle of fire door closer

As the name implies, the door closer is used to close the door. When a fire occurs, the fire door will automatically close after someone pushes the door open and runs out. It is a very practical and indispensable component installed above the fire door. Having said that, how does the door closer work?

1.Installation method of fire door closer

The most commonly used door closers are exterior door closers, and their installation methods are as follows:

(1)The door closer is installed on the hinge side and the door opening side. When installed in this way, the arms of the door closer protrude outwards, approximately 90° to the door frame.

(2)The door closer is installed on the side where the door is closed opposite to the hinge side. Usually an extra bracket provided with the door closer is installed on the arm parallel to the door frame. This usage is usually when you are unwilling to install the door closer on the exterior door that opens outside the building.

(3)The door body is installed on the door frame instead of the door, and the door closer is on the opposite side of the door hinge. This usage can also be used for exterior doors that open outwards, especially those doors that have only a very narrow upper edge, but not wide enough to accommodate the body of the door closer.

2.The working principle of the door closer

How does the door closer on the fire door work? When the door is opened, the door body drives the connecting rod and rotates the transmission gear 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 cavity is also compressed. The one-way valve ball on the left side of the plunger is opened under the action of oil pressure, and the hydraulic oil in the right cavity flows into the left cavity through the one-way valve. When the door opening process is completed, because the spring is compressed during the opening process, the accumulated elastic potential energy is released, pushing the plunger to the left, driving the transmission gear and the door closer link to rotate, and closing the door.

During the spring release process, because the hydraulic oil in the left cavity of the door closer is compressed and the one-way valve is closed, the hydraulic oil can only flow out through the gap between the housing and the plunger, and pass through the small hole on the plunger and 2 The flow channel equipped with the throttle valve core returns to the right cavity. Therefore, the hydraulic oil constitutes resistance to the release of the spring, that is, the buffer effect is achieved by throttling, and the speed of the door closing 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 principles are the same.