| 摘要 |
PURPOSE: A door closing device is provided to securely close a fire door with less power in fires. CONSTITUTION: A door closing device comprises an auxiliary piston, a connector, an auxiliary spring and a fixture. The auxiliary piston is coupled to one side of a cylinder block(10) to slide. The connector is arranged between a piston(20) and an auxiliary piston. The connector removes the piston and the auxiliary piston according to the forward and backward position of the piston. The auxiliary spring is compacted the auxiliary piston and is connected to the auxiliary piston. The fixture fixes the location of the auxiliary piston and is arranged on the cylinder block. The fixture cancels the fixing of the auxiliary piston when the piston is forwarding. |
