Latching and release assembly for hydraulically retarded door closers

Claim 1

In a door closer having a fluid reservoir, a cylinder opening at a tail end to the reservoir and having a head end, a piston slidable in the cylinder and having a fluid passage provided with a check valve for uni-directional flow of fluid from the reservoir to the cylinder head end, means operably connecting the piston to a door for moving the piston towards the tail end of the cylinder when the door is moved from a closed to an open position, a return spring reacting against the piston normally urging the latter towards the cylinder head end, and a restricted fluid return passage having a port at one end opening through a wall of the cylinder adjacent the cylinder head end and communicating at an opposite end with a reservoir for enabling return of fluid from the cylinder to the reservoir so as to enable the door to close under the action of the return spring: a latching and release assembly including: a. an electromagnet adapted to be secured at and close the head end of the cylinder and adapted to be connected to a source of electric power, b. a ferromagnetic valve element having a slidably sealing fit in the cylinder between the piston and the electromagnet moveable by the piston, when the door is closed, to a locking position against the electromagnet and blocking the return fluid passage and being adapted to be maintained in said locking position by the magnet when the latter is in an energized condition to hydraulically lock the piston at the tail end of the cylinder when the door is opened so as to prevent closure of the door, said valve element including a ferromangnetic disc having a fluid passage and a pair of longitudinally spaced peripheral 0-rings embracing the disc for effecting fluid sealing engagement with the walls of the cylinder, the 0-rings being spaced so as to straddle the port of the fluid return passage when the valve element is in the locking position.