Engaging/disengaging fail-safe door closing device for rolling fire door and door machine having same

A door machine 1, comprising:

• a housing 2 enclosing an accommodation room 3 having two opening ends, said accommodation room 3 being formed therein with a radial partition 4, which divides said accommodation room into a first accommodation room 3a and a second accommodation room 3b, as well as is extendingly provided with a bearing part 5 toward said first accommodation room 3a at the center of said partition 4;
• a power means 10 coupled to one of said opening ends of said housing 2 and provided with a shaft 11 passing through the center of said bearing part 5 and extending toward the other opening end;
• a speed reducing means 50 connected to said the other opening end of said housing 2 and used to transmit power from said shaft 11 to an output shaft 52 by means of a plurality of gear sets 51;
• an electromagnet means 30, composed of a winding 33 and a magnet core 34, being accommodated within said first accommodation room 3a and fixed on said partition 4, a hollow aperture 31 at the center of said magnet core 34 being embracingly provided around the outside of said bearing part 5, and an accommodation space 32 being remained between said hollow aperture and said bearing part 5;
• a brake means 40 including a shaft sleeve 41 loosely embracing around the outside of said shaft 11 and axially sliding between said shaft and said bearing part 5, on one end of said shaft sleeve, there being fixed with an attracted plate 43 located within said first accommodation room 3a and facing said magnet core 34;
• while on the other end thereof, there being radially formed with a brake disk 44 located within said second accommodation room 3b, as well as a plurality of locating pins 45 fixed on said partition 4 being used to limit said brake disk 44 to axially slide only, and a plurality of brake linings 46 being provided on one end surface of said brake disk 44 facing outward;
• an elastic element 35 accommodated within said accommodation space 32 and having two ends, one of which is rested against said partition 4, while the other is pressed against said attracted plate 43;
• a driving plate 12 located within said second accommodation room 3b and fixed at the center thereof on said shaft 11, while facing a position where said brake plate 44 and said brake lining 46 are allowed to contact;
• and
• a circuit used to control said door machine 1, such that said winding 33 of said electromagnet means 30 is electrified to excite in order for actuating the brake when said door is opened to a predetermined location, or that the brake is released when the power is cut off.